[Paleopsych] BBS: (Mealey) The Sociobiology of Sociopathy
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The Sociobiology of Sociopathy
Below is the unedited preprint (not a quotable final draft) of:
Mealey, L. (1995). The sociobiology of sociopathy: An integrated
evolutionary model. Behavioral and Brain Sciences 18 (3): 523-599.
The final published draft of the target article, commentaries and
Author's Response are currently available only in paper.
Department of Psychology
College of St. Benedict
St. Joseph, MN 56374
sociobiology, sociopathy, psychopathy, antisocial personality,
evolution, criminal behavior, game theory, emotion, moral development,
Sociopaths are "outstanding" members of society in two senses:
politically, they command attention because of the inordinate amount
of crime they commit, and psychologically, they elicit fascination
because most of us cannot fathom the cold, detached way they
repeatedly harm and manipulate others. Proximate explanations from
behavior genetics, child development, personality theory, learning
theory, and social psychology describe a complex interaction of
genetic and physiological risk factors with demographic and
micro-environmental variables that predispose a portion of the
population to chronic antisocial behavior. Recent evolutionary and
game theoretic models have tried to present an ultimate explanation of
sociopathy as the expression of a frequency-dependent life history
strategy which is selected, in dynamic equilibrium, in response to
certain varying environmental circumstances. This target article tries
to integrate the proximate, developmental models with the ultimate,
evolutionary ones. Two developmentally different etiologies of
sociopathy emerge from two different evolutionary mechanisms. Social
strategies for minimizing the incidence of sociopathic behavior in
modern society should consider the two different etiologies and the
factors which contribute to them.
Sociopaths, who comprise only 3-4% of the male population and less
than 1% of the female population (Strauss & Lahey 1984, Davison and
Neale 1994, Robins, Tipp & Przybeck 1991), are thought to account for
approximately 20% of the United States' prison population (Hare 1993)
and between 33% and 80% of the population of chronic criminal
offenders (Mednick, Kirkegaard-Sorensen, Hutchings, Knop, Rosenberg &
Schulsinger 1977, Hare 1980, Harpending & Sobus 1987). Furthermore,
whereas the "typical" U.S. burglar is estimated to have committed a
median five crimes per year before being apprehended, chronic
offenders- those most likely to be sociopaths- report committing
upward of fifty crimes per annum and sometimes as many as two or three
hundred (Blumstein & Cohen 1987). Collectively, these individuals are
thought to account for over 50% of all crimes in the U.S. (Loeber
1982; Mednick, Gabrielli & Hutchings 1987, Hare 1993).
Whether criminal or not, sociopaths typically exhibit what is generally
considered to be irresponsible and unreliable behavior; their attributes
include egocentrism, an inability to form lasting personal commitments and
a marked degree of impulsivity. Underlying a superficial veneer of
sociability and charm, sociopaths are characterized by a deficit of the
social emotions (love, shame, guilt, empathy, and remorse). On the other
hand, they are not intellectually handicapped, and are often able to
deceive and manipulate others through elaborate scams and ruses including
fraud, bigamy, embezzlement, and other crimes which rely on the trust and
cooperation of others. The sociopath is "aware of the discrepancy between
his behavior and societal expectations, but he seems to be neither guided
by the possibility of such a discrepancy, nor disturbed by its occurrence"
(Widom 1976a, p 614). This cold- hearted and selfish approach to human
interaction at one time garnered for sociopathy the moniker "moral
insanity" (McCord 1983, Davison & Neale 1990).
Sociopaths are also sometimes known as psychopaths or antisocial
personalities. Unfortunately, the literature reflects varied uses of these
three terms (Hare 1970, Feldman 1977, McCord 1983, Wolf 1987, Eysenck
1987). Some authors use one or another term as a categorical label, as in
psychiatric diagnosis or in defining distinct personality "types"; an
example is the "antisocial personality" disorder described in the
Diagnostic and Statistical Manual of the American Psychiatric Association
(1987). Other authors use the terms to refer to individuals who exhibit,
to a large degree, a set of behaviors or personality attributes which are
found in a continuous, normal distribution among the population at large;
an example of such usage is "sociopathy" as defined by high scores on all
three scales of the Eysenck Personality Questionnaire- extraversion,
neuroticism, and psychoticism (Eysenck 1977, 1987).
Other authors make a distinction between "simple" and "hostile" (Allen,
Lindner, Goldman & Dinitz 1971), or "primary" and "secondary" psychopaths
or sociopaths (Fagan & Lira 1980), reserving the term "simple" or
"primary" for those individuals characterized by a complete lack of the
social emotions; individuals who exhibit antisocial behavior in the
absence of this emotional deficit are called "hostile" or "secondary"
psychopaths or sociopaths, or even "pseudopsychopaths" (McCord 1983).
Other authors also make a typological distinction, using the term
"psychopath" to refer to anti-social individuals who are of relatively
high intelligence and middle to upper socio-economic status and who
express their aberrant behavior in impressive and sometimes socially
skilled behavior which may or may not be criminal, such as insider trading
on the stock market (e.g. Bartol 1984). These authors reserve the term
"sociopath" for those antisocial persons who have relatively low
intelligence and social skills or who come from the lower socio- economic
stratum and express their antisocial nature in the repeated commission of
violent crime or crimes of property.
I will begin by using the single term "sociopath" inclusively. However, by
the end of the paper I hope to convince the reader that the distinction
between primary and secondary sociopaths is an important one because there
are two different etiological paths to sociopathy, with differing
implications for prevention and treatment.
My basic premise is that sociopaths are designed for the successful
execution of social deception and that they are the product of
evolutionary pressures which, through a complex interaction of
environmental and genetic factors, lead some individuals to pursue a
life history strategy of manipulative and predatory social
interactions. On the basis of game theoretic models this strategy is
to be expected in the population at relatively low frequencies in a
demographic pattern consistent with what we see in contemporary
societies. It is also expected to appear preferentially under certain
social, environmental, and developmental circumstances which I hope to
In an effort to present an integrated model, I will use a variety of
arguments and data from the literature in sociobiology, game theory,
behavior genetics, child psychology, personality theory, learning
theory, and social psychology. I will argue that: (1) there is a
genetic predisposition underlying sociopathy which is normally
distributed in the population; (2) as the result of selection to fill
a small, frequency-dependent, evolutionary niche, a small, fixed
percentage of individuals- those at the extreme of this continuum-
will be deemed "morally insane" in any culture; (3) a variable
percentage of individuals who are less extreme on the continuum will
sometimes, in response to environmental conditions during their early
development, pursue a life-history strategy that is similar to that of
their "morally insane" colleagues; and (4) a subclinical manifestation
of this underlying genetic continuum is evident in many of us,
becoming apparent only at those times when immediate environmental
circumstances make an antisocial strategy more profitable than a
1. The Model:
1.1 The evolutionary role of emotion
As the presenting, almost defining characteristic of sociopaths is
their apparent lack of sincere social emotions in the absence of any
other deficit such as mental retardation or autism (Hare 1980), it
seems appropriate to begin with an examination of some current models
Plutchik (1980) put forth an evolutionary model of emotion in which he
posits eight basic or "primary" emotions (such as fear, anger and
disgust) which predate human evolution and are clearly related to
survival (1). According to the model, everyone (including sociopaths)
experiences these primary emotions, which are cross- cultural and
instinctively programmed. "Secondary" and "tertiary" emotions, on the
other hand, are more complex, specifically human, cognitive
interpretations of varying combinations and intensities of the primary
emotions (2). Because they are partly dependent upon learning and
socialization, secondary emotions, unlike primary emotions, can vary
across individuals and cultures. Thus, the social emotions (such as
shame, guilt, sympathy, and love), which are secondary emotions, can
be expected to exhibit greater variability.
Griffiths (1990) points out that most of the important features of
emotion argue for an evolutionary design: emotions are generally
involuntary, and are often "intrusive" (p 176); they cause rapid,
coordinated changes in the skeletal/muscular system, facial
expression, vocalization, and the autonomic nervous system; they are
to a large extent innate, or at least "prepared" (see Seligman 1971);
and they do not seem as responsive to new information about the
environment as do beliefs. Griffiths argues that emotional responses
to stimuli (he calls them "affect-programs" after Ekman 1971) are
informationally-encapsulated, complex, organized reflexes, which are
"adaptive responses to events that have a particular ecological
significance for the organism" (p 183). That is, they are likely to be
highly specialized reflexive responses elicited spontaneously by the
presence of certain critical stimuli, regardless of the presence of
possible mediating contextual cues or cognitive assessments.
Nesse (1990) likewise posits an evolutionary model in which emotions
are: "specialized modes of operation, shaped by natural selection, to
adjust the physiological, psychological, and behavioral parameters of
the organism in ways that increase its capacity and tendency to
respond to the threats and opportunities characteristic of specific
kinds of situations" (p 268). He attributes a particular role to the
social emotions, a role he couches in the language of reciprocity and
game theory. Presenting a classic Prisoner's Dilemma matrix, he notes
which emotions would be likely to be associated with the outcomes of
each of the four cells: when both players cooperate, they experience
friendship, love, obligation, or pride; when both cheat or defect,
they feel rejection and hatred; when one player cooperates and the
other defects, the cooperator feels anger while the defector feels
anxiety and guilt.
Given that these emotions are experienced AFTER a behavioral choice is
made, how could they possibly be adaptive? Nesse's explanation is
based on the models of Frank (1988) and Hirshleifer (1987), which
posit that ex post facto feelings lead to behavioral expressions which
are read by others and can be used to judge a person's likely future
behavior. To the extent that the phenomenological experience of
emotion serves to direct a person's future behavior (positive emotions
reinforce the preceding behavior while negative emotions punish and,
therefore, discourage repetition of the behavior), the outward
expression of emotion will serve as a reliable indicator to others as
to how a person is likely to behave in the future. Indeed, that there
exist reliable, uncontrollable outward expressions of these inner
experiences at all suggests that the expressions must be serving a
communicative function (Dimberg 1988).
But if, as in the case of the Prisoner's Dilemma, the most rational
strategy is to be selfish and defect, why should the positive
(reinforcing) emotions follow mutual cooperation rather than the
seemingly more adaptive behavior of defection? Here lies the role of
reputation. If a player is known, through direct experience or social
reputation, always to play the "rational" move and defect, then in a
group where repeated interactions occur and individuals are free to
form their own associations, no rational player will choose to play
with the known defector, who will thus no longer be provided the
opportunity for any kind of gain-- cooperative or exploitative. To
avoid this social "shunning" based on reputation (3) and hence, to be
able to profit at all from long-term social interaction, players must
be able to build a reputation for cooperation. To do so, most of them
must in fact, reliably cooperate, despite the fact that cooperation is
not the "rational" choice for the short-term. Frank and Hirshleifer
suggest that the social emotions have thus evolved as "commitment
devices" (Frank) or "guarantors of threats and promises"
(Hirshleifer)- they cause positive or negative feelings that act as
reinforces or punishers, molding our behavior in a way that is not
economically rational for the short-term but profitable and adaptive
in situations where encounters are frequent and reputation is
Frank presents data from a variety of studies suggesting that people
do often behave irrationally (emotionally) in many dyadic and triadic
interactions- sometimes even when it is clear that there will be no
future opportunity to interact again with the same partner. These
studies support the suggestion that in social situations, one's
emotional response will often prevail over logic, and that the reason
is that such behavior is, in the long-term, adaptive under conditions
when one's reputation can follow or precede one. (See also Farrington
1982, Caldwell 1986, Anawalt 1986, Axelrod 1986, Alexander 1987, Irons
1991, Dugatkin 1992, and Frank, Gilovich & Regan 1993 for more on the
role of reputation.)
According to these models, emotion serves both as a motivator of
adaptive behavior and as a type of communication: the phenomenological
and physiological experience of emotion rewards, punishes, and
motivates the individual toward or away from certain types of stimuli
and social interactions, while the outward manifestations of emotion
communicate probable intentions to others.
Once such reliable communicative mechanisms have evolved, however,
when communication of intent precedes interaction, or when one's
reputation precedes one, the conditions of interaction become
vulnerable to deception through false signalling or advance deployment
of enhanced reputation (e.g. Caldwell 1986). Those who use a deceptive
strategy and defect after signalling cooperation are usually referred
to as "cheaters" and, as many authors have pointed out (e.g. Trivers
1971, Alexander 1987, Dennett 1988, Quiatt 1988), the presence of
cheaters can lead to a coevolutionary "arms race" in which potential
interactors evolve finely tuned sensitivities to likely evidence or
cues of deception, while potential cheaters evolve equally fine-tuned
abilities to hide those cues (4).
As long as evolutionary pressures for emotions to be reliable
communication and commitment devices leading to long-term, cooperative
strategies coexist with counter-pressures for cheating, deception, and
"rational" short-term selfishness, a mixture of phenotypes will
result, such that some sort of statistical equilibrium will be
approached. Cheating should thus be expected to be maintained as a
low-level, frequency-dependent strategy, in dynamic equilibrium with
changes in the environment which exist as counter-pressures against
its success. This type of dynamic process has been modelled
extensively by evolutionary biologists who use game theory- the topic
I turn to next.
1.2 Game theory and evolutionarily stable strategies
Game theory was first introduced into the literature of evolutionary
biology by Richard Lewontin (1961), who applied it to the analysis of
speciation and extinction events. It was later taken up in earnest by
John Maynard Smith and colleagues (eg. Maynard Smith & Price 1973,
Maynard Smith 1974, Maynard Smith 1978) who used it to model contests
between individuals. Maynard Smith showed that the "evolutionarily
stable strategies" (ESSs) that could emerge in such contests included
individuals' use of mixed, as well as fixed, strategies. Alexander
(1986) writes "It would be the worst of all strategies to enter the
competition and cooperativeness of social life, in which others are
prepared to alter their responses, with only preprogrammed behaviors"
The maintenance of mixed ESSs in a population can theoretically be
accomplished in at least four ways (after Buss 1991): (1) through
genetically based, individual differences in the use of single
strategies (such that each individual, in direct relation to genotype,
consistently uses the same strategy in every situation); (2) through
statistical use by all individuals of a species-wide, genetically
fixed, optimum mix of strategies (whereby every individual uses the
same statistical mix of strategies, but does so randomly and
unpredictably in relation to the situation); (3) through species-wide
use by all individuals of a mix of environmentally-contingent
strategies (such that every individual uses every strategy, but
predictably uses each according to circumstances); (4) through the
developmentally-contingent use of single strategies by individuals
(such that each individual has an initial potential to utilize every
type of strategy, but, after exposure to certain environmental stimuli
in the course of development, is phenotypically canalized from that
point on, to use only a fraction of the possible strategies). To
Buss's fourth mechanism can be added a differential effect of genotype
on developmental response to the environment, thus adding another
mechanism: (5) genetically based individual differences in response to
the environment, resulting in differential use by individuals of
environmentally-contingent strategies (such that individuals of
differing genotypes respond differently to environmental stimuli in
the course of development and are thus canalized to produce a
different set of limited strategies given the same, later conditions).
Following the leads of Kenrick, Dantchik, & MacFarlane (1983),
MacMillan & Kofoed (1984), Kofoed & MacMillan (1986), Harpending &
Sobus (1987), and Cohen & Machalek (1988), I would like to suggest an
evolutionary model in which sociopaths are a type of cheater- defector
in our society of mixed-strategy interactionists. I will be arguing
that sociopathy appears in two forms, according to mechanisms 1 and 5
(above), one version that is the outcome of frequency-dependent,
genetically based individual differences in use of a single
(antisocial) strategy (which I will refer to as "primary sociopathy")
and another that is the outcome of individual differences in
developmental response to the environment, resulting in the
differential use of cooperative or deceptive social strategies (which
I will refer to as "secondary sociopathy"). To support this model, I
will provide evidence that there are predictable differences in the
use of cheating strategies across individuals, across environments,
and within individuals across environments; this evidence will
integrate findings from the fields of behavior genetics, child
psychology, personality theory, learning theory, and social
2. The Evidence:
2.1 Behavior genetics
For decades, evidence has been accumulating that both criminality and
sociopathy have a substantial heritable component, and that this
heritable component is to a large extent overlapping; that is, the
heritable attributes that contribute to criminal behavior seem to be
the same as those which contribute to sociopathy. While there is no
one-to-one correspondence between those individuals identified as
criminals and those identified as sociopaths, (indeed, the definitions
of both vary from study to study), it is clear that these two sets of
individuals share a variety of characteristics and that a subset of
individuals share both labels (Moffitt 1987, Ellis 1990b, Robins, Tipp
& Przybeck 1991, Gottesman & Goldsmith 1993).
2.1.1 Studies of criminal behavior
The behavior-genetic literature on criminal behavior suggests a
substantial effect of heredity across several cultures (5).
Christiansen (1977a&b), Wilson & Hernnstein (1985), Cloninger &
Gottesman (1987), Eysenck & Gudjonsson (1989), and Raine (1993) review
studies of twins which, taken as a whole, suggest a heritability of
approximately .60 for repeated commission of crimes of property.
[Heritability is a measure of the proportion of variance of a trait,
within a population, that can be explained by genetic variability
within that population; it thus, ranges theoretically from 0.00 to
1.00, with the remaining population variance explained by variance in
individuals' environment.] Adoption studies (reviewed in Hutchings &
Mednick 1977, Mednick & Finello 1983, Wilson & Hernnstein 1985,
Cloninger & Gottesman 1987, Mednick, Gabrielli & Hutchings, 1987,
Eysenck & Gudjonsson 1989, and Raine 1993) arrive at a similar
conclusion (but see footnote 6).
Several adoption studies were also able to demonstrate significant
interactive effects not discriminable using the twin methodology.
Crowe (1972, 1974), Cadoret, Cain & Crowe (1983), Mednick & Finello
(1983), and Mednick, Gabrielli & Hutchings (1984) report significant
gene-environment interactions, such that adoptive children with both a
genetic risk (criminal biological parent) and an environmental risk
(criminality, psychiatric illness, or other severe behavioral
disturbance in an adoptive parent), have a far greater risk of
expressing criminal behavior than do adoptees with no such risk or
only one risk factor, and that increased risk is more than simply an
additive effect of both risk factors. In addition, Baker, Mack,
Moffitt & Mednick (1989) report an interaction based on sex, in which
females are more likely to transmit a genetic risk to their offspring
than are males.
2.1.2 Studies of sociopathy
The literature on sociopathy suggests a pattern similar to that on
criminality: Schulsinger (1972/77), Cadoret (1978), Crowe (1974),
Cadoret & Cain (1980), Cadoret, Troughton & O'Gorman (1987), and
Cadoret & Stewart (1991) demonstrate a substantial heritability to
sociopathy; Cadoret, Troughton, Bagford & Woodworth (1990) found a
gene-environment interaction similar to the one found for criminal
behavior; and Cadoret & Cain (1980, 1981) found an interaction
involving sex, such that male adoptees were more sensitive to the
influence of environmental risk factors than were female adoptees.
The similarity of the patterns described in these two domains is to
some extent due to the fact that the diagnosis of sociopathy is often
based in part upon the existence of criminal activity in a subject's
life history. On the other hand, consider the following: (1) criminal
behavior and other aspects of sociopathy are correlated (Eysenck 1977,
Morrison & Stewart 1971, Cadoret, Cain & Crowe 1983, Wolf 1987,
Cloninger & Gottesman 1987, Patterson, DeBaryshe & Ramsey 1989); (2)
criminal activity is found with increased frequency among the
adopted-away children of sociopaths (Moffitt 1987); and (3) sociopathy
is found with increased frequency among the adopted-away children of
criminals (Cadoret & Stewart 1991, Cadoret, Troughton, Bagford &
Woodworth 1990). This all suggests that the criminality and sociopathy
may share some common heritable factors. For this reason, early
researchers and clinicians (e.g. Schulsinger 1972/77 and Cadoret 1978)
suggested using the term "antisocial spectrum" to incorporate a
variety of phenotypes that are considered likely to be manifestations
of closely related genotypes (7). The existence of this spectrum
suggests a multifactorial, probably polygenic, basis for sociopathy
and its related phenotypes. Using an analogy to "g", which is often
used to refer to the common factor underlying the positive
correlations between various aptitude measures, Rowe (1986) and Rowe
and Rodgers (1989) use "d" to refer to the common factor underlying
the various expressions of social deviance.
2.1.3 Sex differences and the "two-threshold" model
Cloninger put forth a "two threshold" polygenic model to account for
both the sex difference in sociopathy and its spectral nature
(Cloninger, Reich & Guze 1975; Cloninger, Christiansen, Reich &
Gottesman 1978). According to the model, sociopaths are individuals on
the extreme end of a normal distribution whose genetic component is
(1) polygenic and (2) to a large degree, sex-limited. [Sex- limited
genes, not to be confused with sex-linked genes, are those which are
located on the autosomes of both sexes but which are triggered into
expression only within the chemical/hormonal microenvironment of one
sex or the other. Common examples include beard and mustache growth in
men, and breast and hip development in women.] If a large number of
the many genes underlying sociopathy are triggered by testosterone or
some other androgen, many more men than women will pass the threshold
of the required number of active genes necessary for its outward
According to the two-threshold model, those females who do express the
trait must have a greater overall "dose" or "genetic load" (i.e, they
are further out in the extreme of the normal distribution of
genotypes) than most of the males who express the trait. This
proposition has been supported by data showing that in addition to the
greater overall risk for males as opposed to females, there is a also
greater risk for the offspring (and other relatives) of female
sociopaths as compared to the offspring (and other relatives) of male
sociopaths. This phenomenon cannot be accounted for either by
sex-linkage or by the differential experiences of the sexes.
Besides providing a proximate explanation for the greater incidence of
male sociopathy and crime, the two-threshold model also explains on a
proximate level the finding that males are more susceptible to
environmental influences than females. Somewhat paradoxically, while a
male will express sociopathy at a lower "genetic dose" than is
required for expression in a female, the heritability of the trait is
greater for females, meaning that the environmental component of the
variance is greater for males (8).
The two-threshold model thus explains in a proximate sense what
sociobiologists would predict from a more ultimate perspective. The
fact that males are more susceptible than females to the environmental
conditions of their early years fits well with sociobiological theory,
in that the greater variance in male reproductive capacity makes their
"choice" of life strategy somewhat more risky and therefore more
subject to selective pressures (Symons 1979, Buss 1988, Mealey & Segal
1993). Sociobiological reasoning thus leads to the postulate that
males should be more sensitive to environmental cues that (1) trigger
environmentally-contingent or developmentally-canalized life history
strategies or (2) are stimuli for which genetically based individual
differences in response thresholds have evolved. (Recall mechanisms 3,
4 & 5 for the maintenance of mixed-strategy ESSs in a population.)
If the evolutionary models apply then when, specifically, would
sociopathy be the best available strategy? and what would be the
environmental cues which, especially for boys, would trigger its
development? To answer these questions, I turn to the child psychology
literature, with a special focus on studies of life history
strategies, delinquency, and moral development.
2.2 Child psychology
2.2.1 Life history strategies
Beginning with Draper and Harpending's now-classic 1982 paper on the
relationship between father absence and reproductive strategy in
adolescents, there has been an increasing effort to view development
as the unfolding of a particular life history strategy in response to
evolutionarily relevant environmental cues (Draper & Harpending 1982,
Surbey 1987, MacDonald 1988, Crawford & Anderson 1989, Draper & Belsky
1990, Gangestad & Simpson 1990, Mealey 1990, Belsky, Steinberg &
Draper 1991, Moffitt, Caspi, Belsky & Silva 1992, Mealey & Segal
1993). These models are based either implicitly or explicitly on the
assumption that there are multiple evolutionarily adaptive strategies
and that the optimal strategy for particular individuals will depend
both upon their genotype and their local environment. To date, most
developmental life history models address variance in reproductive
strategies (for example, age at menarche or first sexual activity,
number of mating partners, and amount of parental investment), but
this type of modeling can also be applied to the adoption of social
strategies such as cheating versus cooperation.
Perhaps the most oft-mentioned factor suggested as being relevant to
the development of a cheating strategy, especially in males, is being
competitively disadvantaged with respect to the ability to obtain
resources and mating opportunities. Theoretically, those individuals
who are the least likely to outcompete other males in a status
hierarchy, or to achieve mates through female choice, are the ones
most likely to adopt a cheating strategy. (See eg. Thornhill & Alcock
1983, Daly & Wilson 1983 and Gould & Gould 1989 re: non-human animals,
and Symons 1979, Kenrick et al 1983, MacMillan & Kofoed 1984, Kofoed &
MacMillan 1986, Cohen & Machalek 1988, Tooke & Camire 1991 and
Thornhill & Thornhill 1992 re: humans). In humans, competitive
disadvantage could be related to a variety of factors, including age,
health, physical attractiveness, intelligence, socioeconomic status,
and social skills.
Criminal behavior, one kind of cheating strategy, is clearly related
to these factors. Of the seven cross-cultural correlates of crime
reported by Ellis (1988), three -large number of siblings, low
socio-economic status, and urban residency- seem directly related to
resource competition; the four others -youth, maleness, being of black
racial heritage, and coming from a single parent (or otherwise
disrupted) family background- can be plausibly argued to be related to
competition as well (see eg., Kenrick et al 1983, Wilson & Hernnstein
1985, Ellis 1988, and Cohen & Machalek 1988). Empirical data suggest
that deficits in competitive ability due to psychosis (Hodgins 1992),
intellectual handicap (Moffitt & Silva 1988, Quay 1990a, Stattin &
Magnusson 1991, Hodgins 1992), or poor social skills (Hogan & Jones
1983, Simonian, Tarnowski & Gibbs 1991, Garmezy 1991, Dishion,
Patterson, Stoolmiller & Skinner 1991) are also associated with
criminal behavior. Likewise, the competitive advantages conferred by
high intelligence (Hirschi & Hindenlang 1977, Wilson & Herrnstein
1985, Silverton 1988, Kandel, Mednick, Kirkegaard-Sorensen, Hutchings,
Knop, Rosenberg, & Schulsinger 1988, White, Moffitt & Silva 1989) or
consistent external support (Garmezy 1991), can mitigate the
development of criminal or delinquent behavior in those who are
otherwise at high risk.
Rape and spouse abuse, other forms of cheating strategy, appear to be
related to the same life history factors as crime (Ellis 1989 & 1991a,
Malamuth, Sockloskie, Koss & Tanaka 1991, Thornhill & Thornhill 1992).
In fact, Huesmann, Eron, Lefkowitz & Walder (1984), Rowe and Rodgers
(1989) and Rowe, Rodgers, Meseck-Bushey & St. John (1989) present
evidence that there is a common genetic component to the expression of
sexual and nonsexual antisocial behavior. Given the overlaps between
rape, battering, and criminality in terms of life history
circumstances, genetics, and apparent inability to empathize with
one's victim, it would be parsimonious to postulate that they might be
expressions of a single sociopathy spectrum. As such, these antisocial
behaviors could be considered to be genetically influenced,
developmentally- and environmentally-contingent cheating strategies,
utilized when a male finds himself at a competitive disadvantage (see
also Figueredo & McCloskey nd).
Along these lines, MacMillan and Kofoed (1984) presented a model of
male sociopathy based on the premise that sexual opportunism and
manipulation are the key features driving both the individual
sociopath and the evolution of sociopathy. Harpending and Sobus (1987)
posited a similar basis for the evolution and behavioral
manifestations of Briquet's Hysteria in women, suggesting that this
syndrome of promiscuity, fatalistic dependency, and attention-
getting, is the female analogue, and homologue, of male sociopathy.
Childhood delinquency is a common precursor of adolescent delinquency
and adult criminal and sociopathic behavior (Robins & Wish 1977,
Loeber 1982, Loeber & Dishion 1983, Loeber & Stouthamer- Loeber 1987,
Patterson et al 1989); in fact, childhood conduct disorder is a
prerequisite finding in order to diagnose adult antisocial personality
(APA 1987). Importantly, just as in the literature on adults, a
distinction is frequently made between two subtypes of conduct
disorder in children: Lytton (1990), for example, distinguishes
between "solitary aggressive type" and "group type"; Loeber (1990)
distinguishes between "versatiles" and "property offenders"; and
Strauss & Lahey (1984) distinguish between "unsocialized" and
"socialized". I will argue that these subtypes are precursors of two
types of adulthood antisociality (with "solitary aggressive",
"versatile", or "unsocialized" types leading to primary sociopathy and
"group", "property offender", or "socialized" types presaging
secondary sociopathy). I will also argue that the differing life
history patterns of these two types of delinquents are reflections of
two different evolutionary mechanisms for maintaining ESSs in a
population- mechanism 1 and mechanism 5, respectively (see Section
Although more than half of juvenile delinquents outgrow their behavior
(Lytton 1990, Robins, Tipp & Przybeck 1991, Gottesman & Goldsmith
1993), the frequency of juvenile antisocial behaviors is still the
best predictor of adult antisocial behavior, and the earlier such
behavior appears, the more likely it is to be persistent (Farrington
1986, Loeber & Stouthamer-Loeber 1987, Lytton 1990, Stattin &
Magnusson 1991, White, Moffitt, Earls, Robins & 2Silva 1990, and
Robins, Tipp & Przybeck 1991). The mean age at which adult sociopaths
exhibited their first significant symptom is between eight and nine
years; 80% of all sociopaths exhibited their first symptom by age
eleven (Robins, Tipp & Przybeck 1991); over two-thirds of eventual
chronic offenders are already distinuishable from other children by
kindergarten (Loeber & Stouthamer-Loeber 1987). Thus, by evaluating
the environments of juvenile delinquents, we can fairly reliably
reconstruct the childhood environments of adult sociopaths.
Studies of this sort consistently implicate several relevant
environmental factors correlated with boyhood antisocial behavior:
inconsistent discipline, parental use of punishment as opposed to
rewards, disrupted family life (especially father absence, family
violence, alcoholic parent, or mentally ill parent), and low
socioeconomic status (Cadoret 1982, Loeber & Dishion 1983, van Dusen,
Mednick, Gabrielli & Hutchings 1983, Wilson & Hernnstein 1985,
Farrington 1986 & 1989, McCord 1986, Silverton 1988, & Patterson et al
1989, Lytton 1990, Offord, Boyle & Racine 1991). Besides the fact that
all of these variables are more likely to exist when one or the other
parent is sociopathic, and the child hence, genetically predisposed to
sociopathy, behaviorist and social learning models of the dynamics of
early parent-child interactions (to be described in Section 2.4.2)
have been fairly convincing in explaining how antisocial behaviors can
be reinforced under such living conditions.
Interestingly, in line with the postulate that cheating strategies
would be most likely to be used by individuals who are at a
competitive disadvantage, McGarvey, Gabrielli, Bentler & Mednick
(1981), Loeber & Dishion (1983), Hogan & Jones (1983), Magid &
McKelvie (1987), Kandel et al (1988), Hartup (1989), and Patterson et
al (1989) all suggest that the common way in which high risk familial
and environmental factors contribute to delinquency, is by
handicapping children with respect to their peers, in terms of social
skills, academic ability, and self-esteem. This noncompetitiveness
then leads disadvantaged youths to seek alternative peer groups and
social environments in which they can effectively compete (Dishion et
al 1991). If they are successful in the estimation of their new peer
group, adopting this strategy may lead to "local prestige" (Rowe,
personal communication) sufficient to commandeer resources, deter
rivals, or gain sexual opportunities within the new referent group
(see also Moffitt 1993). In other words, competitively disadvantaged
youth may be trying to "make the best of a bad job" (Dawkins 1980,
Cohen & Machalek 1988), by seeking a social environment in which they
may be less handicapped or even superior.
The correlates of delinquency in girls are essentially the same as
those for boys, although delinquency is less common in girls (Robins
1986, Lytton 1990, White, Moffitt, Earls, Robins & Silva 1990). Caspi,
Lynam, Moffitt & Silva (1993) found that delinquency in girls, as in
boys, is arrived at via two different developmental trajectories. One
pattern includes a history of antisocial behavior throughout childhood
and a tendency to seek out delinquent peers; based on previous
research (White, Moffitt, Earls, Robins & Silva 1990), this life
history trajectory is thought to lead to persisten antisocial behavior
in adulthood. The second pattern is exhibited by girls who have few
behavior problems in childhood, but who, upon reaching menarche,
exhibit more and more frequent antisocial behaviors. The antisocial
behavior of girls who show this latter pattern is thought to be more a
product of environmental influence than that of girls who follow the
first trajectory, as this pattern is selectively exhibited by girls
who (a) have an early age of menarche and (b) are in coeducational
school settings. These girls, upon reaching early sexual maturity,
start associating with older male peers and exhibiting some of the
antisocial behaviors that are more often displayed by older boys than
their younger female peers (see Maccoby 1986); girls who follow this
trajectory are expected to "outgrow" their antisocial activites.
Although the two subsets of delinquent girls would be difficult to
differentiate using a cross- sectional methodology, in accordance with
the model presented here, Caspi et al. consider their differing
developmental histories to be of theoretical importance for
longitudinal studies and of practical importance for early
intervention. (See Moffitt 1993 for a similar scenario regarding
2.2.3 Moral development
Like the tendency to engage in antisocial behavior, an individual's
tendency to engage in prosocial behavior seems to be fairly stable
from an early age (Rushton 1982). Yet the development of individual
differences in behavior has not been as well studied as the presumably
universal stages of cognition that underlie changes in moral
reasoning. Kohlberg's (1964) stage model of moral development, for
example, ties advances in moral thinking to advances in reasoning
ability and attributes individual differences largely to differences
in cognitive ability. While it is clear that both moral reasoning and
moral behavior covary with age (Rushton 1982) and may do so in a
manner consistent with some evolutionists' thinking (e.g. Alexander
1987), cognitive models alone cannot explain the absence of moral
behavior in sociopaths, who are not intellectually handicapped with
respect to the normal population.
Other developmental models posit the emergence of empathy and the
other social emotions as prerequisites for moral behavior (see Zahn-
Waxler & Kochanska 1988 for a review). Even very young children, it
seems, are in a sense biologically prepared to learn moral behavior,
in that they are selectively attentive to emotions- especially
in others (Hoffman 1978, Zahn-Waxler & Radke-Yarrow 1982, Radke-
Yarrow & Zahn-Waxler 1986). Hoffman (1975, 1977, 1982), for example,
suggests that the observation of distress in others triggers an innate
"empathic distress" response in the child, even before the child has
the cognitive capacity to differentiate "other" from "self".
Accordingly, any instrumental behavior which serves to reduce the
distress of the other also serves to relieve the vicarious distress of
the child. Thus, very young children might learn to exhibit prosocial
behavior long before they are able to conceptualize its effect on
In Hoffman's model, the motivation behind early prosocial behavior is
the (egocentric) need to reduce one's own aversive feelings of arousal
and distress. As the child ages, the range of cues and stimuli which
can trigger the vicarious distress increase through both classical and
operant conditioning. Eventually, when the child develops the
cognitive ability to "role play" or take on another's perspective,
empathic distress turns to "sympathetic distress", which motivates
prosocial behavior that is more likely to be interpreted as
intentional, altruistic, and moral. Hoffman's model of prosocial
behavior dovetails nicely with Hirshleifer's (1987) "Guarantor" and
Frank's (1988) "Commitment" model of emotion (see section I.A.): the
reduction in anxiety which follows cooperative or prosocial behavior
reinforces such behavior, while the increase in anxiety which, through
stimulus generalization, follows acts or thoughts of antisocial
behavior will punish and therefore reduce those acts and thoughts.
Dienstbier (1984) reported an interesting series of studies testing
the role of anxiety and emotional arousal on cheating. As expected,
high arousal levels were associated with low cheating levels (and vice
versa), but the subjects' attribution of the cause of high arousal was
also important. When subjects were able to attribute their arousal to
a cause other than the temptation to cheat, they found it much easier
to cheat than when they had no other explanation for their arousal
level. Subjects were also less willing to work to avoid punishment
when they were able to attribute their arousal to an external cause
rather than to an internal source of anxiety associated with the
threat of punishment. Dienstbier concluded that when a situation is
perceived to be "detection-free", one's temptation to cheat is either
resisted or not, depending on the levels of anxiety perceived to be
associated with the temptation.
The ability to act intentionally in either a prosocial or antisocial
manner (or in terms of game theory, cooperatively or deceptively),
depends upon having reached a certain level of cognitive development
at which it is possible to distinguish emotions of the self from
emotions of others, i.e., the child must pass from empathic responses
to sympathetic responses (Dunn 1982, Hoffman 1975, 1977, 1984,
Mitchell 1986, Vasek 1986). This transition begins to occur some time
during the second year (Hoffman 1975, 1982, Leslie 1987, Dunn 1987,
1988, and Dunn, Brown, Slomkowski, Tesla & Youngblade 1991) when the
child is beginning to develop what has come to be called a "theory of
mind" (Premack & Woodruff 1978).
Having a theory of mind allows one to impute mental states (thoughts,
perceptions, and feelings) not only to oneself, but also to other
individuals. Humphrey (1976, 1983) suggests that this kind of
awareness evolved in humans because it was a successful tool for
predicting the behavior of others. Humphrey claims that the best
strategists in the human social game would be those who could use a
theory of mind to empathize accurately with others and thereby be able
to predict the most adaptive strategy or play in a social interaction.
(Byrne & Whiten 1988 call this aptitude "Machiavellian intelligence".)
Humphrey's model is something of a cognitive equivalent of the
evolutionary models of emotion discussed in section 1.1; they can
probably be considered complementary and mutually reinforcing. With
regard to sociopathy, the question is whether a strategist can be
successful using only the cognitive tool of a theory of mind, without
access to emotional, empathic information which, presumably,
sociopaths lack (Mealey 1992). In the next section I will argue that
this is exactly what a sociopath does.
2.3 Personality theory
The models of normative moral development presented above are helpful
but clearly insufficient to explain sociopathy. Although some adoption
studies and most longitudinal studies report significant effects of
social and environmental risk factors on delinquency and criminality,
the magnitude of that risk as a simple main effect is rather small.
Despite repeated exposure to inconsistent and confusing reinforcement
and punishment, most children who grow up with these risk factors do
not turn out to be sociopathic, whereas some children who do not
experience such risk factors, do. Studies have repeatedly shown that
the effect of the environment is much more powerful for children at
biological risk than for others. What is it that makes "high risk"
environmental features particularly salient for those individuals who
have a certain predisposing genotype?
2.3.1 The role of gene-environment interactions
Stimulated by the work of Rowe and Plomin (Rowe & Plomin 1981, Rowe
1983a&b, 1990a&b; Plomin & Daniels 1987, Dunn & Plomin 1990), evidence
is accumulating that, unlike what has been traditionally assumed, the
most important environmental features and events that influence
personal development are not those that are shared by siblings within
a family (such as parenting style, socioeconomic status, and
schooling), but rather, are idiosyncratic events and relationships
which are difficult to study systematically with traditional methods.
Despite a shared home, individual children will encounter different
microenvironments: their individual relationships with their parents
will differ, and their experiences on a day to day, minute by minute
basis will not overlap significantly. In addition, there will be some
environmental differences which are due to genetic differences;
children with different personalities, aptitudes, and body types, will
not only seek out different experiences (Scarr & McCartney 1983,
Caspi, Elder & Bem 1987, Rowe 1990a), but will also attribute
different phenomenological interpretations to the same experiences
(Rowe 1983a & 1990b, Dunn 1992). For these reasons, any two children
will experience an (objectively) identical environment in different
ways; there is, in some sense, no real validity to some of the
operational measures we currently use to describe a child's
environment (Rowe & Plomin 1981, Plomin & Daniels 1987, Wachs 1992).
Although this may sound discouraging for those who seek to apply
psychological research to the prevention of crime and delinquency -
and most such efforts have, in fact, been fairly unsuccessful (Feldman
1977, Gottschalk, Davidson, Gensheimer & Mayer 1987, Borowiak 1989 and
Patterson et al 1989)- there are reasons for optimism. Palmer (1983)
suggests that the "nothing works" conclusion is valid only in the
sense that no single intervention technique will be successful across
the board, and that targeting different strategies to different
individuals should prove more successful. More and more studies are
suggesting that there are at least two developmental pathways to
delinquency and sociopathy and that we need to address them separately
(Quay 1990b, Lytton 1990, White et al 1990, Caspi et al 1993, Moffitt
1993, Dishion & Poe 1993, Patterson 1993, McCord 1993, Simons 1993).
The evolutionary model presented here makes specific predictions about
the likely differential success of different intervention and
prevention strategies for individuals arriving at their anti-social
behavior via different paths: while individuals of differing genotypes
may end up with similar phenotypes, different environmental elements
and experiences may be particularly salient for them. (This is a
corollary of mechanism 5 for the maintenance of ESSs presented in
As will be argued below, primary and secondary sociopathy seem to
provide an excellent illustration of the development of similar
phenotypes from different genotype-environment interactions. To the
extent that we understand it now, primary sociopaths come from one
extreme of a polygenic genetic distribution and seem to have a
genotype that disposes them "to acquire and be reinforced for
displaying antisociality" (Rowe 1990a, p 122). That genotype results
in a certain inborn temperament or personality, coupled with a
particular pattern of autonomic arousal, that, together, seem to
design the individual (1) to be selectively unresponsive to those
environmental cues which are necessary for normal socialization and
moral development and (2) to actively seek the more deviant and
arousing stimuli within the environment. Secondary sociopaths, on the
other hand, are not as genetically predisposed to their behavior;
rather, they, are more responsive to environmental cues and risk
factors, becoming sociopathic "phenocopies" (after Raine 1993) or
"mimics" (after Moffitt 1993) when the carrying capacity of the
"cheater" niche grows. What are the predisposing constitutional
factors that place some individuals at high risk?
2.3.2 The role of temperament
In a twin study, Rushton, Fulker, Neale, Nias & Eysenck (1986) found
evidence of substantial heritability of self-reported measures of
altruism, nurturance, aggressiveness, and empathy. Across twin pairs,
altruism, nurturance, and empathy increased with age, while
aggressiveness decreased; sex differences (in the expected direction)
were found for nurturance, empathy, and aggression; for all measures,
the environmental contributions were determined to be individual
rather than familial. Methodological considerations do not allow full
confidence in the numerical heritability estimates of this study, but
Eisenberg, Fabes & Miller (1990) conclude that it reports true
individual differences which are likely to be a result of genetic
differences in temperament, specifically sociability and emotionality.
More recently, two additional twin studies have confirmed the findings
of Rushton et al. Emde, Plomin, Robinson, Corley, DeFries, Fulker,
Reznick, Campos, Kagan & Zahn-Waxler (1992) reported significant
heritabilities for empathy, behavioral inhibition, and expressions of
negative affect, while Ghodsian-Carpey & Baker (1987) found
significant heritabilities on four measures of aggressiveness in
children. Like the Rushton et al study, both of these studies also
reported sex differences, and both confirmed the relative importance
of nonshared, as opposed to shared, environmental influences.
A fourth twin study (Rowe 1986) used a different set of personality
indices but went a step further in establishing the link between
temperament and antisocial behavior. Rowe's analysis suggests that,
especially for males, the inherited factors correlated with one's
genetic risk of delinquency are the same as those that lead to the
temperamental attributes of anger, impulsivity, and deceitfulness
("self-serving dishonesty with people with whom a person ordinarily
has affectional bonds" p 528). Interestingly, while Rowe found that
common genetic factors related temperament and delinquency, it was
environmental factors which related academic nonachievement with
delinquency. These findings provide evidence for the two-pathway model
presented in Section 1.2, in that such a gene-environment interaction
(1) would create at least two possible routes to sociopathy or
criminality, one primarily heritable and one less so, and (2) in terms
of the latter, less heritable pathway, would set the stage for
developmentally- and environmentally-contingent individual differences
in antisocial behavior. In addition, in line with previously mentioned
studies and the proposed model, the environmental factors Rowe found
to be statistically significant varied within families and were more
significant for males than for females.
Most of the research into the relationship between temperament,
personality and sociopathy has been based on the extensive work of
Hans Eysenck (summarized in Eysenck 1977 & 1983, Eysenck & Gudjohnsson
1989, and Zuckerman 1989). Eysenck first postulated and then
convincingly documented that sociopathy in particular and antisocial
behavior in general are correlated with high scores on all three of
the major personality dimensions of the Eysenck Personality
Questionnaire: 'extraversion' (contra introversion), 'neuroticism'
(contra emotional stability), and 'psychoticism' (contra fluid and
efficient superego functioning- not synonymous with psychotic mental
illness; Zuckerman (1989) suggests that this scale would be better
called 'psychopathy'). All three of these dimensions exhibit
substantial heritability, and since psychoticism is typically much
higher in males than females, it is a likely candidate for one of the
relevant sex-limited traits which fits Cloninger's two-threshold risk
model explaining the sex difference in expression of sociopathy.
In trying to explain the proximate connections between temperament,
delinquency, sociopathy, and criminal behavior, Eysenck and colleagues
devised the "General Arousal Theory of Criminality" (summarized in
Eysenck & Gudjohnsson 1989), according to which the common biological
condition underlying all of these behavioral predispositions is the
inheritance of a nervous system which is relatively insensitive to low
levels of stimulation. Individuals with such a physiotype, it is
argued, will be extraverted, impulsive, and sensation-seeking, because
under conditions of relatively low stimulation they find themselves at
a suboptimal level of arousal; to increase their arousal, many will
participate in high-risk activities such as crime (see also Farley
1986 and Gove & Wilmoth 1990). In general support of this model, Ellis
(1987) performed a meta-analysis which found that both criminality and
sociopathy were associated with a variety of indicators of suboptimal
arousal, including childhood hyperactivity, recreational drug use,
risk-taking, failure to persist on tasks, and preference for
wide-ranging sexual activity.
Additional confirmation of the arousal model comes from Zuckerman, who
found a similar pattern of behaviors associated with his measure of
sensation-seeking. (The following summary is derived from Zuckerman
1979, Zuckerman, Buschbaum & Murphy 1980, Daitzman & Zuckerman 1980,
and Zuckerman 1983, 1984, 1985, 1990 & 1991). In addition to seeking
thrill and novelty, sensation-seekers describe "a hedonistic pursuit
of pleasure through extraverted activities including social drinking,
parties, sex, and gambling", "an aversion to routine activities or
work and to dull and boring people", and "a restlessness in an
unchanging environment" (Zuckerman et al 1980, p 189). In college
students, sensation-seeking is correlated with the Pd (Psychopathic
Deviate) scale of the Minnesota Multiphasic Personality Inventory, and
among prisoners it can be used to distinguish primary psychopaths from
secondary psychopaths and non- psychopathic criminals (see also Fagan
& Lira 1980). Zuckerman also shows that sensation-seeking as a
temperament appears at an early age (3-4 years), exhibits a high
degree of heritability, correlates negatively with age in adults, and
exhibits sex differences, with higher scores more often in males.
Because it shows a relationship with both sex and age,
sensation-seeking (and its presumed underlying hypoarousal) may also
be a good candidate for a trait which can explain the distribution and
expression of sociopathy (see also Baldwin 1990).
Gray (1982, 1987), and Cloninger (Cloninger 1987a, Cloninger, Svrakic
& Przybeck 1993) have proposed updated versions of the Eysenck model
in which the three personality factors are rotated and renamed so as
to more clearly correspond to known neural circuitry. Gray names the
three systems: the approach, or, behavioral activation system, the
behavioral inhibition system, and the fight/flight system; Cloninger
names them "novelty-seeking", "harm- avoidance", and
"reward-dependence". The three factors explain the same variance in
personality as Eysenck's original factors and have been shown to be
independent and highly heritable (Cloninger 1987). In addition to
mapping more closely to known neural systems, these three factors are
also proposed to correspond to differential activity of three
neurochemicals: dopamine for behavioral activation (or
novelty-seeking), serotonin for behavioral inhibition (or harm
avoidance), and norepinephrine for fight/flight (or reward
dependence); see Depue & Spoont 1986, Cloninger 1987, Charney, Woods,
Krystal & Heninger 1990, Eysenck 1990, and Raine 1993 for partial
2.3.3 The role of physiology
Using Cloninger's terminology, sociopaths are individuals who are high
on novelty-seeking, low on harm-avoidance, and low on reward-
dependence. Thus, we should expect them to be high on measures of
dopamine activity, low on measures of serotonin activity, and low on
measures of norepinephrine activity; data suggest that they are.
Zuckerman (1989) reports that sensation-seeking is negatively
correlated with levels of dopamine-beta-hydroxylase (DBH), the enzyme
which breaks down dopamine, and that extremely low levels of DBH are
associated with undersocialized conduct disorder and psychopathy.
Importantly, with respect to the two-pathway model, boys with
socialized conduct disorder (those with fewer, later- appearing
symptoms, and who are posited to be at risk for secondary, as opposed
to primary sociopathy), had high levels of DBH.
In addition, extraverts and delinquents are reported to have lower
than average levels of adrenaline (epinephrine) and norepinephrine
under baseline circumstances; Magnusson (1985 as cited by Zuckerman
1989) reports that urinary epinephrine measures of boys at age 13
significantly predicted criminality at ages 18-25. High sensation-
seekers, criminals, and other individuals scoring high on measures of
impulsivity and aggression also have significantly lower levels than
others of the serotonin metabolite, 5-HIAA (Brown, Goodwin, Ballenger,
Goyer & Major 1979, Brown, Ebert, Goyer, Jimerson, Klein, Bunney &
Goodwin 1982, Muhlbauer 1985, Depue & Spoont 1986, Zuckerman 1989,
1990, Kruesi, Hibbs, Zahn, Keysor, Hamburger, Bartko & Rapoport 1992,
and Raine 1993). These are not small effects: Raine (1993) reports an
average effect size (the difference between groups divided by the
standard deviation) for serotonin of .75, and for norepinephrine of
.41; Brown et al (1979) reported that 80% of the variance in
aggression scores of their sample was explained by levels of 5-HIAA
alone; and Kruesi et al reported that knowing 5- HIAA levels increased
the explained variance of aggression at a two- year follow-up from 65%
(using clinical measures only) to 91% (clinical measures plus 5-HIAA
Levels of monoamine oxidase (MAO)- an enzyme which breaks down the
neurotransmitters serotonin, dopamine, epinephrine, and
are also low in antisocial and sensation-seeking individuals
(Zuckerman 1989, 1990, Ellis 1991b). Individual differences in
platelet MAO appear shortly after birth and are stable (Zuckerman
1989, 1990 and Raine 1993); Zuckerman reports an estimated
heritability of .86. Recently, a mutant version of the gene coding for
MAO-A, the version of MAO specific to serotonin, has been identified
in an extended family in which the males show a history of repeated,
unexplained outbursts of aggressive behavior (Brunner, Nelen,
Breakefield, Ropers & van Oost 1993, Morrell 1993); urinalysis
indicated that the MAO-A is not functioning normally in the affected
Results of psychophysiological studies also report significant
differences between sociopaths and others. [Reviews of this literature
can be found in Mednick, Moffitt & Stack (1987), Trasler (1987), Raine
(1989), Eysenck & Gudjohnsson (1989), Raine & Dunkin (1990), Zuckerman
(1990), and Raine (1993).] Among the findings are that: high
sensation-seekers and sociopaths are more likely than lows and normals
to show orienting responses to novel stimuli of moderate intensity,
whereas lows and normals are more likely to show defensive or startle
responses; criminals and delinquents tend to exhibit a slower alpha
(resting) frequency in their electroencephalogram (EEG) than
age-matched controls; high sensation-seekers and delinquents differ
from lows and nondelinquents in the amplitude and shape of cortical
evoked potentials; extraverts and sociopaths show less physiological
arousal than introverts and normals in response to threats of pain or
punishment and more tolerance of actual pain or punishment; and
delinquents (though not necessarily adult criminals) tend to have
lower baseline heart rate than nondelinquents.
The importance of the role of these psychophysiological factors as
significant causes, not just correlates, of sociopathy, is
strengthened by evidence that (a) these measures of autonomic
reactivity are just as heritable as the temperament they are
associated with (Zuckerman 1989, Gabbay 1992), and that (b) the same
physiological variables which differentiate identified sociopaths,
delinquents, and criminals from others can also significantly predict
later levels of antisocial behavior in unselected individuals (Loeb &
Mednick 1977 using skin conductance; Volavka, Mednick, Gabrielli,
Matousek & Pollock 1984 using EEG; Satterfield 1987 using EEG; Raine,
Venable & Williams 1990a using EEG, heart rate, and skin conductance;
and Raine, Venables & Williams 1990b using evoked potentials). As for
the reports on neurochemistry, these are effects are not small; Raine
(1993) reports that for heart rate, the average effect size across ten
studies was .84.
Another important physiological variable in the distribution of
sociopathic behavior is testosterone. Testosterone (or one of its
derivatives) is a likely candidate for the role of trigger of the
sex-limited activation of genes required by the two-threshold model
presented earlier. The mechanism of action of steroid hormones is to
enter the nucleus of the cell and interact with the chromosomes,
regulating gene expression. This differential activity of the genes
leads to some of the individual, age, and sex differences we see in
temperament, specifically, psychoticism, aggression, impulsivity,
sensation-seeking, nurturance, and empathy (Zuckerman et al 1980,
Zuckerman 1984, 1985, 1991 and Ellis 1991b). Variation in testosterone
levels also parallels the age variation in the expression of
sociopathic behavior and is correlated with such behavior in
adolescent and adult males (Daitzman & Zuckerman 1980, Zuckerman 1985,
Rubin 1987, Olweus 1986, 1987, Schalling 1987, Susman, Inoff-Germain,
Nottelman, Loriaux, Cutler & Chrousos 1987, Ellis & Coontz 1990, Udry
1990, Dabbs & Morris 1990, Gladue 1991 and Archer 1991). Testosterone
is thus likely to play a dual role in the development of sociopathy,
just as it does in the development of other sex differences: one as an
organizer (affecting traits) and one as an activator (affecting
Udry (Drigotas & Udry 1993, Halpern, Udry, Campbell & Suchindran
1993), unable to replicate his own 1990 study suggesting an activating
effect of testosterone, has suggested that the correlation between
testosterone and aggression might be due to a physiosocial feedback
loop; he posits that boys with high, early levels of testosterone
mature faster, and, being bigger, are more likely to get in fights.
Since levels of testosterone, adrenaline, and serotonin have been
shown to fluctuate in response to social conditions (McGuire, Raleigh
& Johnson 1983, Raleigh, McGuire, Brammer & Yuwiler 1984, Schalling
1987, Olweus 1987, Raleigh, McGuire, Brammer, Pollack & Yuwiler 1991,
Archer 1991, Kalat 1992), this sociophysiological interaction creates
a positive feedback loop: those who start out with high levels of
testosterone and sensation seeking (and low levels of adrenaline,
serotonin, and MAO) are (1) more likely than others to initiate
aggressive behavior, and (2) more likely to experience success in
dominance interactions, leading to (3) an increased probability of
experiencing further increases in testosterone, which (4) further
increases the likelihood of continued aggressive behavior.
Another example of a sociophysiological feedback loop comes from Dabbs
and Morris (1990), who found significant correlations between
testosterone levels and antisocial behavior in lower class men but not
in upper class men. They explained this by positing that upper class
men are more likely, because of differential socialization, to avoid
individual confrontations. If this is true, it would mean that upper
class men are, because of their socialization, specifically avoiding
those types of social encounters which might raise their testosterone
(and in turn, their antisocial behavior). This interpretation is
supported by the finding (in the same study) that significantly fewer
upper class than lower class men had high testosterone levels. Thus,
it is possible that upper class socialization may mitigate the
influence of testosterone. An alternative explanation- that the
aggressive behavior associated with higher testosterone levels leads
to downward social mobility- also suggests a recursive
Raine (1988) has argued that since upper class children are less
likely than lower class children to suffer the environmental risks
predisposing one toward sociopathic behavior, when such behavior is
seen in upper class individuals, it is likely to be the result of a
particularly strong genetic predisposition. Evidence supporting this
has been reported by three independent studies. Wadsworth (1976) found
physiological indicators of hypoarousal amongst upper- class, but not
lower-class, boys who subsequently became delinquent. Raine (Raine &
Venables 1981, 1984; also reported in Raine 1988 and Raine & Dunkin
1990) found indicators of hypoarousal in his upper- class antisocial
subjects, but the reverse in his lower-class subjects. Satterfeld
(1987) found that of his lower-class subjects, those in a biological
high-risk group were seven times more likely to have been arrested
than those in his control group, whereas among his middle- and
upper-class subjects, the rate was 25 and 28 times, respectively. This
outcome was a result of lower rates of criminal activity in the
control groups of the middle- and upper-class subjects as compared to
the lower-class controls; i.e., almost all of those who had been
arrested from the middle- and upper-class were biologically at high
risk, but this was not true for the lower class subjects. The
implications of these findings are of tremendous import, as they
suggest that (1) the effect of the social environment might be
considerably larger than suggested by adoption studies, and (2) there
might be different etiological pathways to sociopathy, and therefore
different optimal strategies for its prevention or remediation,
depending upon what kind of social and environmental background the
person has experienced.
2.4 Learning Theory
Adoption studies show that the environment clearly plays an important
role in the etiology of sociopathy, but that its effects are different
for individuals of different genotype. As mentioned in section 2.3.1,
some of this difference is likely to be a result of gene-environment
correlations, in that different environments are sought by individuals
of different genotypes; some will be a result of differences in
interpretation of the same environment by individuals of different
genotypes; and some will be a result of differences in environment
impinging upon people because of differences in their genotype (e.g.
discriminating parental treatment of two children differing in
temperament). In nonadoptive families, gene-environment correlations
will be even stronger because parents with certain personality types
will provide certain environments for their children. These
differential effects of environment on individuals of varying genetic
risk for sociopathy become readily apparent when we examine the effect
of the interaction between physiotype and conditioning on the process
There is evidence that individuals with a hypoaroused nervous system
are less sensitive than most people to the emotional expression of
other individuals, and to social influences in general (Eliasz &
Reykowski 1986, Eysenck 1967 as cited in Patterson and Newman 1993).
They are also less responsive to levels and types of stimuli that are
normally used for reinforcement and punishment (Eliasz 1987); as a
result, they are handicapped in learning through autonomic
conditioning although they exhibit no general intellectual deficit
(e.g. Hare & Quinn 1971, Eysenck 1977, Mednick 1977, Ziskind, Syndulko
& Maltzman 1978, Gorenstein & Newman 1980, Newman, Widom & Nathan
1985, Raine 1988, Lytton 1990, Zuckerman 1991).
One of the posited consequences of this learning deficit is a reduced
ability to be socialized by the standard techniques of reward and
punishment that are used (especially in the lower classes and by
uneducated parents) on young children. In particular, hypoaroused
individuals have difficulty inhibiting their behavior when both reward
and punishment are possible outcomes (Newman, Widom & Nathan 1985,
Newman & Kosson 1986, Newman 1987, Zuckerman 1991, Patterson & Newman
1993); in situations when most people would experience an
approach-avoidance conflict, sociopaths and extraverts are more likely
to approach; (see also Dienstbier 1984). Because of their high levels
of sensation-seeking, children with a hypoaroused nervous system will
be more likely than other children to get into trouble, and when they
do, will be less likely to be affected by, and learn from, the
consequences whether those consequences are a direct result of their
behavior or an indirect result such as parental punishment.
Despite continuing problems with operational definitions, recent
research suggests that there might be distinguishable differences in
learning between primary and secondary sociopaths, or children with
unsocialized versus socialized conduct disorder (Newman et al 1985,
Gray 1987, Quay 1990b, Newman, Kosson & Patterson 1992). Primary
sociopaths, with their inability to experience the social emotions,
exhibit deficits on tasks which typically induce anxiety in others,
specifically, passive avoidance tasks, approach-avoidance tasks, and
tasks involving punishment, but they can learn well under other
conditions (Raine, Venables & Williams 1990b, Newman et al 1992,
Patterson & Newman 1993, Raine 1993). Secondary sociopaths and
extraverts, on the other hand, have normal levels of anxiety and
responses to punishment, but they may be especially driven by high
reward conditions (Boddy, Carver & Rowley 1986, Derryberry 1987,
Newman, Patterson, Howland & Nichols 1990).
Primary sociopaths, with diminished ability to experience anxiety and
to form conditioned associations between antisocial behavior and the
consequent punishment, will be unable to progress through the normal
stages of moral development. Unlike most children who are biologically
prepared to learn empathy, they are contraprepared to do so, and will
remain egoistic- unable to acquire the social emotions of empathy,
shame, guilt, and love. They present at an early age with
"unsocialized" conduct disorder. Secondary sociopaths, with normal
emotional capacities, will present, generally at a later age, with
"socialized" conduct disorder (Loeber 1993, Patterson 1993, Simons
1993). What socialization processes contribute to their development?
2.4.2 Social learning
In Section 2.2.1, it was noted that a cheating strategy is predicted
to develop when a male (especially) is competitively disadvantaged,
and that criminal behavior (especially in males) is clearly related to
factors associated with disadvantage. These are: large numbers of
siblings, low socio-economic status, urban residency, low
intelligence, and poor social skills. How, in a proximate sense, do
these variables contribute to the development of secondary sociopathy?
Path models suggest a two-stage process involving a variety of
cumulative risk factors (McGarvey et al 1981, Snyder, Dishion &
Patterson 1986, Snyder & Patterson 1990, Patterson, Capaldi & Bank
1991, Dishion et al 1991, Loeber 1993, Simons 1993, Tremblay 1993,
Moffitt 1993) (9).
In the first stage, disrupted family life, associated with parental
neglect, abuse, inconsistent discipline, and the use of punishment as
opposed to rewards, are critical (Feldman 1977, Wilson & Hernnstein
1985, Snyder et al 1986, McCord 1986, Patterson et al 1989, Luntz &
Widom 1993, Conger 1993, Simons 1993). Poor parenting provides the
child with inconsistent feedback and poor models of prosocial
behavior, handicapping the child in the development of appropriate
social, emotional, and problem-solving skills. This pattern is found
most frequently in parents who are themselves criminal, mentally
disturbed, undereducated, of low intelligence, or socioeconomically
deprived (McGarvey et al 1981, McCord 1986, Farrington 1986), leading
to a cross-generational cycle of increasing family dysfunction (eg.
Jaffe, Suderman & Reitzel 1992, Luntz & Widom 1993).
In the second stage, children with poor social skills find themselves
at a disadvantage in interactions with age-mates; rejected by the
popular children, they consort with one another (Loeber & Dishion
1983, Snyder et al 1986, Kandel et al 1988, Hartup 1989, and Patterson
et al 1989, Dishion et al 1991). In these socially unskilled peer
groups, which will also include primary sociopathic, or, unsocialized
conduct disorder children, delinquent, antisocial behavior is
reinforced and new (antisocial) skills are learned (Maccoby 1986,
Moffitt 1993). Antisocial behavior may then escalate in response to,
or as prerequisite for, social rewards provided by the group, or as an
attempt to obtain the perceived social (and tangible) rewards which
often accompany such behavior (Moffitt 1993). As the focus of the
socialization process moves outside the home, parental monitoring
becomes more important (Snyder et al 1986, Snyder & Patterson 1990,
Forgatch 1991, Dishion et al 1991, Conger 1993, Forgatch, Stoolmiller
& Patterson 1993, Simons 1993), as does the availability of prosocial
alternatives for the socially unskilled adolescent (Farrington 1986,
Apter 1992, Moffitt 1993).
The development of secondary sociopathy appears to depend much more
upon environmental contributions than does primary sociopathy. Since
it is secondary sociopathy which, presumably, has increased so
rapidly, so recently in our culture, what can social psychologists
contribute to our understanding of the sociocultural factors involved
in its development?
2.5 Social Psychology
First, the use of antisocial strategies is not restricted to
sociopaths. The majority of people who are arrested are not
sociopathic, and many people exhibit antisocial behavior that is
infrequent enough or inoffensive enough to preclude arrest. Some
antisocial behavior is even considered acceptable if it is expressed
in socially approved circumstances. Person (1986), for example,
relates entrepreneurism to psychopathy, while Christie (1970) notes
that people who seek to control and manipulate others often become
lawyers, psychiatrists, or behavioral scientists; Jenner (1980), too,
claims that "subtle, cynical selfishness with a veneer of social
skills is common among scientists" (p 128).
Christie (see Christie & Geis 1970) developed a scale for measuring
this subclinical variation in antisocial personality; he called it the
"Machiavellianism" or "Mach" scale. One's Mach score is calculated by
compiling answers to Likert-format queries of agreement or
disagreement with statements like "Humility not only is of no service
but is actually harmful," "Nature has so created men that they desire
everything but are unable to attain it," and "The most important thing
in life is winning". Adults who score high on the Mach scale express
"a relative lack of affect in interpersonal relationships," "a lack of
concern with conventional morality," "a lack of gross
psychopathology," and "low ideological commitment" (Christie & Geis, p
3-4); children who score high on Machiavellianism have lower levels of
empathy than age-mates (Barnett & Thompson 1984).
High Machs have an "instrumental cognitive attitude toward others"
(Christie & Geis, p 277), and, because they are goal-oriented as
opposed to person-oriented, they are more successful in face-to-face
bargaining situations than low Machs. High Machs "are especially able
communicators, regardless of the veracity of their message" (Kraut &
Price 1976). In a related vein, high Machs, like sociopaths, are more
resistant to confession after cheating than are low Machs, and they
are rated as being more plausible liars (Christie & Geis 1970, Bradley
& Klohn 1987); like sociopaths, high Machs are often referred to as
"cool". According to Christie, "If Machiavellianism has any behavioral
definition ...self-initiated manipulation of others should be at its
core" (p 76). One can thus easily think of Machiavellianism as a
low-level manifestation of sociopathy. It even shows a sex difference
consistent with the two- threshold model (Christie & Geis 1970), an
age pattern consistent with age variation in testosterone levels
(Christie & Geis 1970), significant positive correlations with
Eysenck's psychoticism and neuroticism scales (Allsopp, Eysenck &
Eysenck 1991), and a correlation with serotonin levels (Madsen 1985).
In one study, Geis & Levy (1970) found that high Machs (who were
thought to use an "impersonal, cognitive, rational, cool" approach
with others), were much more accurate than low Machs (who were thought
to use a "more personal, empathizing" approach), at assessing how
other "target" individuals answered a Machiavellian attitudes
questionnaire. Even more interesting is the result (from the same
study) that the high Machs achieved their accuracy by using a
nomothetic or actuarial strategy: they guessed that everyone was at
about the average level, without discriminating between individuals
based on differences they had had an opportunity to observe during a
previous experimental session. In addition, their errors tended to be
random, which would fit with reports by Eliasz & Reykowski (1986) and
Damasio, Tranel & Damasio (1990) that hypoaroused and antisocial
individuals are less attentive to social and emotional cues than
others. Low Machs, on the other hand, used an idiographic approach,
and although they successfully differentiated between high scorers and
low scorers, they grossly underestimated the scores of both, guessing
at a level that was more reflective of their own scores than those of
the population at large.
This study suggests two things: (1) that basing one's playing
strategies on an "impersonal, cognitive, rational, cool" approach to
others might be more accurate in the long run than using a "personal,
empathizing" approach (at least in those situations where cooperative
long-term partnerships are not possible); and (2) the errors made by
those who use the personal, empathizing approach, are of the kind more
likely to result in playing the cooperation strategy when the cheating
strategy would be more appropriate (rather than vice versa). Thus, the
personal, empathizing approach is likely to make one susceptible to
being exploited by others who use the impersonal cognitive approach;
indeed, high Machs outcompete low Machs in most experimental
competitive situations (Terhune 1970, Christie & Geis 1970).
As I have argued elsewhere (Mealey 1992), the common assumption that
an empathy-based approach to predicting the behavior of others is
better than a statistical approach is not necessarily correct; this
belief may itself be an emotion-based cognitive bias. To have such a
bias may be beneficial, however, for the same reason that emotional
commitment biases are beneficial: in situations where voluntary,
long-term coalitions can be formed, the personal, empathizing (and
idealistic) low Machs might outperform the more impersonal, cognitive
(and realistic) high Machs, since low Machs would be more successful
than high Machs in selecting a cooperator as a partner.
Although two studies (Hare & Craigen 1974 and Widom 1976a) report on
the strategy of sociopaths in Prisoner's Dilemma-type settings, in
both studies the sociopaths were paired with one another; thus, we do
not have a measure of the strategy sociopaths use against partners of
their own choosing or in situations with random, rotating partners
(10). I would predict that in such settings, sociopaths, (like Geis &
Levy's high Mach subjects), would be less proficient than others in
distinguishing between high and low Mach partners, and would thus be
at a disadvantage in iterated games with a chosen partner; on the
other hand (again like high Mach subjects), they should perform at
better than average levels when playing with randomly assigned,
rotating partners. Widom (1976b) found that when asked to guess how
"people in general" would feel about different social situations
sociopaths guessed that others would feel essentially the same way
that they do, whereas control subjects guessed that others would feel
differently. As in the Geis & Levy study, both groups were wrong, but
in different ways: the sociopaths underestimated their differences
from others, while the control subjects substantially over-estimated
their differences from others, suggesting that sociopaths (like high
Machs) were using a nomothetic approach to prediction, while controls
(like low Machs) were using an idiographic approach.
Machiavellianism and the related propensity to use others in social
encounters has generally been looked upon as a trait. An alternative
perspective, however, acknowledges both the underlying variation in
personality and the situational factors that are relevant to an
individual's behavior at any given moment (eg. Barber 1992). In line
with mechanism 5 for maintaining ESSs (presented in Section I.B.),
Terhune (1970) says "actors bring to the situation propensities to act
in a certain general way, and within the situation their propensities
interact with situational characteristics to determine their specific
behavior" (p 229) (11). This brings us to the last question: Beyond
the constitutional and environmental variables that contribute to the
development of individual differences in personality and antisocial
behavior, what can social psychology tell us about the
within-individual situational factors which encourage or discourage
cheating strategies, and how can these be explained?
2.5.2 The role of mood
Although mood and emotion are not identical concepts, they are clearly
related (12). Mood might be thought of as a relative of emotion which
clearly varies within individuals but is perhaps less an immediate
response to concrete events and stimuli and more a generalized, short-
to mid-term response to the environment. As such, the role of mood
must be addressed by any model that relies so heavily on the concepts
of emotion, emotionality, and emotionlessness, as determinants of
Positive mood and feelings of success have been demonstrated to
enhance cooperative behavior (Mussen & Eisenberg-Berg 1977, Cialdini,
Kenrick & Baumann 1982, Farrington 1982). If, as Nesse (1991) has
argued, positive mood is a reflection not only of past success, but
also of anticipation of future success, the facilitation of
cooperation by positive mood could be seen as part of a long-term
strategy by individuals who feel they can afford to pass up possible
short-term gains for the sake of establishing a cooperative
Sad affect and feelings of failure can also affect strategy in social
interactions. To the extent that sadness and feelings of failure
follow losses of various sorts, individuals in these circumstances
should be expected to be egoistic and selfish. In children, this is
typically what is found (Mussen & Eisenberg-Berg 1977, Baumann,
Cialdini & Kenrick 1981). In some children, and more consistently in
adults, on the other hand, sadness and feelings of failure can
facilitate prosocial behavior. Mussen & Eisenberg-Berg (1977) suggest
that this is a result of a deliberate effort to enhance one's
(diminished) reputation among others; Baumann et al (1981) and
Cialdini et al (1982) suggest that it is a result of a deliberate
effort to relieve negative affect based on prior experience that
prosocial behavior often has a positive, self- gratifying effect.
If sadness is profound, i.e., one is is depressed and experiencing the
cognitive biases and selective attention associated with depression
(Nesse 1991, Sloman 1992, Mineka & Sutton 1992), one would be expected
to desist from all social interaction, being neither antisocial nor
prosocial, but asocial (Nesse 1991, Sloman 1992). In this view, the
lethargy and anhedonia associated with depression could be considered
to be facultative lapses in the emotions or moods which typically
motivate a person toward social interaction.
Hostility can also lead to cognitive biases and selective attention to
relevant social stimuli. Dodge and Newman (1981) showed that
aggressiveness in boys is associated with the over-attribution of
hostile intent to others. The authors concluded that such attributions
lead to increased "retaliatory" aggression by the hostile individuals,
fueling a cycle of true hostility and retaliation by all parties. It
is also abundantly clear that anger and hostility, once expressed, do
not lead to catharsis, but to amplified feelings and outward
expressions of that anger (Tavris 1982).
Guilt, which often follows selfish behavior, typically results in an
increase in subsequent prosocial behavior (Hoffman 1982, Cialdini et
al 1982); Hoffman calls this "reparative altruism". Guilt can easily
be seen as one of Hirshleifer's (1987) or Frank's (1988) emotional
commitment devices, compelling one to perform prosocial behavior as a
means of reestablishing one's tarnished reputation.
Interestingly, Cialdini et al (1982) also report that prosocial
behavior increases after observing another's transgression. They
explain this phenomenon within the context of what they call the
"Negative Relief" model: prosocial behavior is performed as a means of
alleviating negative feelings in general (including direct or
vicarious guilt, sympathy, distress, anxiety, or depression). Like
Hoffman's, this model postulates that the reinforcing power of (relief
provided by) prosocial behavior is learned during childhood.
Since guilt, anxiety and sympathy are social emotions that primary
sociopaths rarely, if ever, experience, there is no reason to expect
that they might moderate their behavior so as to avoid them. On the
other hand, there is no reason to expect that sociopaths don't
experience fluctuations in mood (such as depression, optimism, or
anger) in response to their changing evaluation of their prospects of
success and failure. To the extent that we can manipulate the
sociopath's mood, therefore, we might be able to influence his
2.5.3 Cultural variables
Competition, in addition to being one of the most important variables
in determining long-term life strategy choices, is also one of the
more important situational variables influencing the choice of
immediate strategy. Competition increases the use of antisocial and
Machiavellian strategies (Christie & Geis 1970) and can counteract the
increase in prosocial behavior that generally results from feelings of
success (Mussen & Eisenberg-Berg 1977). Some cultures encourage
competitiveness more than others (Mussen & Eisenberg-Berg 1977,
Shweder, Mahapatra & Miller 1987) and these differences in social
values vary both temporally and crossculturally. Across both
dimensions, high levels of competitiveness are associated with high
crime rates (Wilson & Herrnstein 1985, see also Farley 1986) and
Machiavellianism (Christie & Geis 1970).
High population density, an indirect form of competition, is also
associated with reduced prosocial behavior (Farrington 1982) and
increased antisocial behavior (Wilson & Hernnstein 1985, Ellis 1988,
Robins, Tipp & Przyeck 1991, U.S. Department of Justice 1992)-
especially in males (Wachs 1992; see Section 3.2.1 and references
therein for ultimate, game theoretic explanations why this might
occur; see Draper 1978, Siegel 1986, Gold 1987, Foster 1991, and
Wilson & Daly 1993 for a variety of proximate explanations). Fry
(1988) reports large differences in the frequency of prosocial and
antisocial behaviors in two Zapotec settlements equated for a variety
of socio-ecological variables; the one major difference- thought
possibly to be causal- was in land holdings per capita, with the
higher levels of aggression found in the community with the smaller
per capita land holdings.
Last, but not least, is the relatedness or similarity of the
actors/strategists to their partners in an interaction. Based on
models of kin selection and inclusive fitness, individuals should be
more cooperative and less deceptive when interacting with relatives
who share their genes, or relatives who share investment in common
descendents. Segal (1991) reported that identical twins cooperated
more than fraternal twins playing the Prisoner's Dilemma. Barber
(1992) reported that responses on an altruism questionnaire were more
altruistic when the questions were phrased so as to refer to relatives
(as opposed to "people" in general), and that Machiavellian responses
were thereby reduced. Rushton (Rushton, Russell and Wells 1984,
Rushton 1989) presents evidence that people also cooperate more with
others who are similar to them even though not genetically related.
There are a variety of plausible evolutionary explanations for this
behavior (see Pulliam 1982, Mealey 1984, and BBS commentary on Rushton
3. Integration, Implications, and Conclusions:
3.1 Integration: Sociopathy as an ESS leads to two types of sociopaths
3.1.1 Primary sociopathy
I have thus far argued that some individuals seem to have a genotype
that disposes them "to acquire and be reinforced for displaying
antisociality" (Rowe 1990a, p 122). That genotype results in a certain
inborn temperament or personality, coupled with a particular pattern
of autonomic hypoarousal that, together, design the child to be
selectively unresponsive to cues necessary for normal socialization
and moral development. This scenario is descriptive of mechanism 1
(Section 1.2) of maintaining ESSs in the population; it describes the
existence of frequency-dependent, genetically based individual
differences in employment of life history strategies. I suggest
accordingly, that there will always be a small, cross- culturally
similar, and unchanging baseline frequency of sociopaths: a certain
percentage of sociopaths- those individuals to whom I have referred as
primary sociopaths- will always appear in every culture, no matter
what the socio-cultural conditions. Those individuals will display
chronic, pathologically emotionless antisocial behavior throughout
most of their lifespan and across a variety of situations, a phenotype
which is recognized (according to Robins, Tipp & Przybeck 1991) "by
every society, no matter what its economic system, and in all eras"
(13). Since it is a genetically determined strategy, primary
sociopaths should be equally likely to come from all kinds of
socio-economic backgrounds; on the other hand, since they constitute
that small group of individuals whose physiotype makes them
essentially impervious to the social environment almost all sociopaths
from the upper-classes will be primary sociopaths (14).
Of course, because they are not intellectually handicapped, these
individuals will progress normally in terms of cognitive development
and will acquire a theory of mind. Their's however, will be formulated
purely in instrumental terms, without access to the empathic
understanding that most of us rely on so much of the time. They may
become excellent predictors of others' behavior, unhandicapped by the
vagaries and "intrusiveness" of emotion, acting, as do professional
gamblers, solely on nomothetic laws and actuarial data rather than on
hunches and feelings. In determining how to "play" in the social
encounters of everyday life, they will use a pure cost-benefit
approach based on immediate personal outcomes, with no "accounting"
for the emotional reactions of the others with whom they are dealing.
Without love to "commit" them to cooperation, anxiety to prevent
"defection", or guilt to inspire repentance, they will remain free to
continually play for the short- term benefit in the Prisoner's
3.1.2 Secondary sociopathy
At the same time, because changes in gene-frequencies in the
population would not be able to keep pace with the fast-changing
parameters of social interactions, an additional, fluctuating
proportion of sociopathy should be a result of mechanism 5 for
maintaining ESSs, which allows for more flexibility in the ability of
the population to track the frequency-dependent nature of the success
of the cheating strategy. Mechanism 5 (genetically based individual
differences in response to the environment, resulting in differential
use by individuals of environmentally-contingent strategies) would
explain the development and distribution of what I have referred to as
secondary sociopathy. Secondary sociopathy is expressed by individuals
who are not extreme on the genetic sociopathy spectrum, but who,
because of exposure to environmental risk factors, pursue a life
history strategy that involves frequent, but not necessarily
emotionless cheating. Unlike primary sociopaths, secondary sociopaths
will not necessarily exhibit chronic antisocial behavior, because
their strategy choices will be more closely tied to age, fluctuation
in hormone levels, their competitive status within their referent
group, and changing environmental contingencies. Since secondary
sociopathy is more closely tied to environmental factors than to
genetic factors, secondary sociopaths will almost always come from
lower class backgrounds and their numbers could vary substantially
across cultures and time, tracking environmental conditions favoring
or disfavoring the use of cheating strategies.
The existence of this second etiological pathway to sociopathy
explains the fact that cultural differences are correlated with
differences in the overall incidence of antisocial behavior (Wilson &
Hernnstein 1985, Farley 1986, Gold 1987, Ellis 1988, Robins, Tipp &
Przybeck 1991). It also explains why, as the overall incidence of
sociopathy increases, the discrepancy in the ratio of male to female
sociopaths decreases (Robins, Tipp & Przybeck, 1991): since secondary
sociopathy is less heritable than primary sociopathy (according to
this model), the effect of sex-limited genes (like that of all the
genes contributing to the spectrum) should be less important for the
development of secondary sociopathy, resulting in less of a sex
difference. Based on this model, I would predict that, unlike what we
find for primary sociopathy (see Section 2.1.3), we should find no
differential heritability between the sexes for secondary sociopathy
(even though there will still be a sex difference in prevalence).
3.2 Implications of the two-pathways model
Terhune (1970) suggests that choice of strategy in experimental game
situations (and, presumably, real-life settings as well) depends upon
two things: (1) cognitive expectations regarding others (i.e., a
theory of mind), and (2) motivational/emotional elements such as hopes
and fears. Since primary sociopaths have a deficit in the realm of
emotional motivation, they presumably act primarily upon their
cognitive expectations of others; to the extent that they do act upon
emotions, it is most likely to be upon mood and the primary emotions
(like anger and fear) rather than upon the social and secondary
emotions (like love and anxiety). Thus, the extent to which a society
will be able to diminish the antisocial behavior of primary sociopaths
will depend upon two things: (1) its influence on the sociopath's
cognitive evaluation of its own reputation as a player in the
Prisoner's Dilemma, and (2) the primary emotion- or mood-inducing
capacity of the stimuli it utilizes in establishing the costs and
benefits of prosocial versus antisocial behavior.
Manipulations of these two variables will also influence the numbers
of secondary sociopaths by changing the size of the adaptive niche
associated with antisocial behavior. In addition, since the
development of secondary sociopathy is more influenced by the social
environment than is the development of primary sociopathy, and since
secondary sociopaths are not devoid of social emotions, changing
patterns in the nurturing and socialization of children and in the
socialization and rehabilitation of delinquents and adult criminals is
an additional, viable possibility for reducing the overall prevalence
of antisocial behavior.
3.2.1 Minimizing the impact of primary sociopaths: society as a player
in the Prisoner's Dilemma
Sociopaths' immediate decisions are based partly on their ability to
form a theory of mind, and to use those expectations of others'
behavior in a cost-benefit analysis to assess what actions are likely
to be in their own self-interest. (This is true for both primary and
secondary sociopaths.) The outcome of such analyses is therefore
partially dependent on the sociopath's expectations of the behavior of
other players in the game. I would argue that an entire society can be
seen as a player, and that the past behavior of that society will be
used by the sociopath in forming the equivalent of a theory of mind,
to predict the future behavior of that society.
Like an individual player, a society will have a certain probability
of detecting deception, a more-or-less accurate memory of who has
cheated in the past, and a certain proclivity to retaliate or not,
based upon a cheater's past reputation and current behavior. Since the
sociopath is using a rational and actuarial approach to assess the
costs and benefits of different behaviors, it is the actual past
behavior of the society which will go into his calculations, rather
than risk assessments inflated from the exaggerated fears or anxieties
that most people feel in anticipation of being caught or punished.
Thus, to reduce antisocial behavior, a society must establish and
enforce a reputation for high rates of detection of deception and
identification of cheaters, and a willingness to retaliate. In other
words, it must establish a successful strategy of deterrence.
Game theory models by Axelrod and others have shown that the
emergence, frequency, and stability of social cooperation is subject
to an abundance of potential deterrent factors (Axelrod & Hamilton
1981, Axelrod 1984, Feldman & Thomas 1987, Axelrod & Dion 1988,
Heckathorn 1988, Hirshleifer & Coll 1988, Boyd 1988, Dugatkin & Wilson
1991, Boyd & Richerson 1992, Nowak & Sigmund 1993 and Vila & Cohen
1993). Among these are: group size (as it decreases, cooperation
increases); nonrandom association of individuals within the population
(as it increases, cooperation increases); the probability of error in
memory or recognition of an individual (as it decreases, cooperation
increases); the effect of a loss on a cooperator (as it decreases,
cooperation increases); the effect of a gain on a defector (as it
decreases, cooperation increases); the frequency of punishment against
defectors (as it increases, cooperation increases); the cost of
punishment for the punished (as it increases, cooperation increases);
and the cost of punishment for the punishers (as it decreases,
cooperation increases) (15).
Recent game-theoretic models are coming closer and closer to the
complexity of real-world, human social interactions on a large scale
by examining the role of culture and technology in: expanding
society's collective memory of individual players' past behavior;
broadcasting the costs and benefits of cooperation and defection, and;
the development and application of new socialization,
deception-detection, and punishment techniques (see esp. Hirshleifer &
Rasmusen 1989, Machalek & Cohen 1991, Dugatkin 1992). These models
begin to provide useful strategies for the real-world prediction and
reduction of cheating strategies and antisocial behavior. (See also
Feldman 1977, Farrington 1979, Bartol 1984, Wilson & Herrnstein 1985,
Axelrod 1986, Eysenck & Gudjonsson 1989, Ellis 1990a, and Machalek &
Cohen 1991 for some nonquantitative models and tests which incorporate
some of these variables in their explanation of the socialization,
punishment, and deterrence of crime.)
Since neither secondary nor primary sociopaths have a deficit in the
ability to perform accurate cost-benefit analyses, increasing the
probabilities of criminal detection, identification, and punishment,
can also reduce crime; a society must therefore establish a reputation
for willingness to retaliate. [The National Research Council (1993)
reports that a 50% increase in the probability of incarceration for
any single crime reduces subsequent crime twice as much as does
doubling incarceration duration (p 294).] Harsher penalties can also
be deterring, but only if they are reliably meted out.
Another key is in making the costs of cheating salient. Generally
speaking, antisocial and uncooperative behaviors increase as the costs
become more diffuse or removed in time, and prosocial and cooperative
behaviors decrease as the benefits become more diffuse or removed in
time (Bartol 1984, Ostrom 1990, Low 1993). For primary sociopaths,
this is even moreso, since their sensation- seeking physiotype makes
them particularly unable to make decisions based on nonimmediate
consequences. Although able to focus attention on interesting tasks
for short periods, the sociopath cannot perform well under conditions
of delayed gratification (Pulkkinen 1986) and is more motivated avoid
immediate costs than by threats or avoidance of future punishments
(Christie & Geis 1970, McCord 1983, Raine 1988, 1989, Forth & Hare
1989). Costs associated with social retaliation must therefore not
only be predictable, but be swift- and the swiftness itself, must also
Another factor the sociopath will use to "compute" the potential value
of an antisocial action is the cost-benefit ratio of the alternatives
(Piliavin, Thornton, Gartner & Matsueda (1986). For the sociopath,
money and other immediate tangible rewards are more motivating than
social reinforcers (such as praise) or promises of future payoff, and
visual stimuli are more salient than auditory stimuli (Chesno &
Kilmann 1975, Raine & Venables 1987, Forth & Hare 1989, Raine 1989,
Raine et al 1990b, Zuckerman 1990). Thus, alternatives to crime must
be stimulating enough and rewarding enough to preferentially engage
the chronically hypoaroused sensation-seeker. This will be a difficult
task to achieve, but it will be more successful if we can effectively
distinguish primary from secondary sociopaths. Primary sociopaths,
with their emotional, but not intellectual deficit, will be competent
on some tasks on which secondary sociopaths, with deficits in social
skills, emotion-regulation and problem-solving, will not.
Possibilities might include: novelist, screen play writer, stunt man,
talk show host, disk jockey, explorer, race car driver, or skydiving
exhibitionist. Given that primary sociopaths will always be with us in
low numbers, it would be a wise social investment to create- even on
an individual basis, if necessary- a number of exciting, high- payoff
alternatives for them, in order to minimize the number who may
otherwise cause pain and destruction.
Distinguishing between primary and secondary sociopaths is also
critical for decisions about confinement and rehabilitation. Quinsey &
Walker (1992) cite examples where recidivism rates went up for
psychopaths, but down for nonpsychopaths, after they were exposed to
the same kind of "treatment". Recidivism is much greater in primary
sociopaths than in secondary sociopaths (Hare, Forth & Strachan 1992),
and sometimes the only response is prolongued incapacitation (until
they literally "grow out of it"). A recent international meeting of
experts concluded that "treatment" programs dealing with primary
sociopaths should be "less concerned with attempts to develop empathy
or conscience than with intensive efforts to convince them that their
current attitudes and behavior (simply) are not in their own
self-interest" (Hare 1993, p 204).
3.2.2 Minimizing the prevalence of secondary sociopathy: society as a
socializing agent and mood setter
Given that secondary sociopaths have a different life history and are
more responsive to environmental influences than primary sociopaths,
social changes can be designed to minimize not only their impact, but
their incidence. Loeber (1990) argues that each generation in our
society is being raised with an increasing number of environmental
risk factors, leading to increasing generation-wide deficits in
impulse control. He makes specific suggestions to screen for high-risk
children and institute early intervention, noting that different
interventions are likely to be more or less effective given different
risk factors in the child's or adolescent's life history. (See also
U.S. Department of Justice 1993.)
One possible intervention is parent training (see Magid & McKelvie,
1987 and Dumas, Blechman & Prinz 1992, for reviews and programmatic
suggestions). Laboratory experiments show that antisocial behaviors
can be reduced and prosocial behaviors reinforced by appropriate use
of modelling, induction, and behavioral modification techniques
(Feldman 1977, Mussen & Eisenberg-Berg 1977, Grusec 1982, Rushton
1982, Gelfand & Hartmann 1982, Radke-Yarrow & Zahn-Waxler 1986,
Kochanska 1992 & 1993). Recent longitudinal studies in natural
settings suggest that the positive effects of good parenting,
especially parental warmth and predictability, may be long-lasting
(McCord 1986, Kochanska 1992 & 1993, Kochanska & Murray 1992).
The cause and effect relationship between parental behavior and child
behavior, however, is not likely to be one-way. Children of different
gender, temperaments, and even social classes, respond differentially
to different socialization techniques (Dienstbier 1984, Radke-Yarrow &
Zahn-Waxler 1986, Lytton 1990, Kochanska 1991 & 1993, Kochanska &
Murray 1992, McCord 1993), and to some extent, difficult children
elicit poor parenting (Buss 1981, Lee & Bates 1985, Bell & Chapman
1986, Snyder & Patterson 1987, Lytton 1990, Eron, Huesmann & Zelli
1991). It is easy for parents of difficult children to lose heart, and
in so doing, become even less effective (Patterson 1992). For example,
studies cited in Landy & Peters (1992) found that mothers of
aggressive children, like other mothers with a low sense of personal
power, tend to give weak, ineffectual commands to their children.
This lack of "goodness of fit" between parental style and the needs of
the child is probably an important factor in the exacerbation of
conduct disorder (Lee & Bates 1985, Landy & Peters 1992, Wachs 1992,
Moffitt 1993). Parents need help in identifying high-risk children and
they need instruction in how to take a practical, assertive approach
with them (see Magid & McKelvie 1987, Garmezy 1991), while using a
more inductive, empathic approach with their other children (see
Kochanska 1991, Kochanska & Murray 1992, and Kochanska 1993).
Social workers, health care providers, and employees of the criminal
justice system also need to be able to distinguish between children
with different risk factors and life histories and to respond
accordingly. Palmer (1983) argues that agents should be individually
matched with each client/offender based on style and personality
characteristics, to prevent high Mach and sociopathic offenders from
taking advantage of low Mach employees.
At a broader level, many sociocultural aspects of modern society seem
to contribute to antisocial behaviors and attitudes (National Research
Council 1993, Moffitt 1993). As a society gets larger and more
competitive, both theoretical models (Section 3.2.1) and empirical
research (Section 2.4.2) show that individuals become more anonymous
and more Machiavellian, leading to reductions in altruism and
increases in crime. Social stratification and segregation can also
lead to feelings of inferiority, pessimism, and depression among the
less privileged, which can in turn promote the use of alternative
competitive strategies, including antisocial behavior (Sanchez 1986,
Magid & McKelvey 1987, Wilson & Daly 1993).
Crime may be one response to the acquisition of an external locus of
control (Raine, Roger & Venables 1982) or learned helplessness.
Learned helplessness and other forms of depression have been
associated with reduced levels of serotonin (Traskman, Asberg,
Bertilsson & Sjostrand 1981); since reduced levels of serotonin have
also been shown to be related to increased aggression, it is likely
that physiological changes mediate these psychological and behavioral
changes. The neurochemical pathway involved in learned helplessness
(identified by Petty & Arnold 1982) appears to be the same one
identified by Gray (1982, 1987) and Cloninger (1987a) with mediation
of behavioral inhibition/harm avoidance, and by Charney et al (1990)
with anxiety-mediated inhibition.
Crime may also function to obtain desirable resources, increase an
individual's status in a local referent group, or provide the
stimulation that the more privileged find in more socially acceptable
physical and intellectual challenges (eg. Farrington 1986, Farley
1986, Lyng 1990, Apter 1992, Moffitt 1993). According to Apter, "the
vandal is a failed creative artist," a bored and frustrated
sensation-seeker who "does not have the intellectual or other skills
and capacities to amuse or occupy himself" (1992, p 198). Thus, in
addition to making the costs of antisocial behavior greater, strong
arguments can be made for providing early social support for those at
risk, and for developing alternative, nonexploitative,
sensation-seeking ventures that can meet the psychological needs of
disadvantaged and low-skill individuals.
A review of the literature in several areas supports the concept of
two pathways to sociopathy:
(1) "Primary sociopaths" are individuals of a certain genotype,
physiotype, and personality who are incapable of experiencing the
secondary, "social" emotions that normally contribute to behavioral
motivation and inhibition; they fill the ecological niche described by
game theorists as the "cheater strategy" and, as the result of
frequency-dependent selection, will be found in low frequency in every
(1b) To minimize the damage caused by primary sociopaths, the
appropriate social response is to modify the criminal justice system
in ways that obviously reduce the benefits and increase the costs of
antisocial behavior, while simultaneously creating alternatives to
crime which could satisfy the psychophysiological arousal needs of the
(2) "Secondary sociopaths" are individuals who use an
environmentally-contingent, facultative cheating strategy not as
clearly tied to genotype; this strategy develops in response to social
and environmental conditions related to disadvantage in social
competition and will thus covary (across cultures, generations, and
even within an individual lifetime) with variation in immediate social
(2b) To reduce the frequency of secondary sociopathy, the appropriate
social response is to implement programs which reduce social
stratification, anonymity, and competition, intervene in high-risk
settings with specialized parent education and support; and increase
the availability of rewarding, prosocial opportunities for at-risk
Since the genetics and life histories of primary and secondary
sociopaths are so different, successful intervention will require
differential treatment of different cases; we thus need to encourage
the widespread adoption of common terminology and diagnostic criteria.
1. Plutchik's eight primary emotions are: anger, fear, sadness,
disgust, surprise, joy, acceptance, and anticipation. Others posit a
few more (Izard 1977, 1991) or fewer (Ekman 1971, Panskepp 1982) but
what is basically agreed is that primary emotions are those which can
be found in other mammals, are hard-wired in the brain, are
reflexively produced in response to certain stimuli, are associated
with certain, sometimes species-specific, physiological responses
(e.g., piloerection, changes in heart rate, facial expressions), and,
in humans, are found cross-culturally and at an early age. (See Ortony
& Turner 1990 for a dissenting opinion.)
Note that the "social emotions", including love, guilt, shame, and
remorse, do not meet the above criteria, and are not considered to be
primary emotions by most authors (see Izard 1991 for another
perspective). Although distinctly human, the social emotions seem to
involve a critical element of learning, and, central to the argument I
will be making, are not panhuman.
2. According to Plutchik, cognitive processes themselves evolved "in
the service of emotions... in order to make the evaluations of
stimulus events more correct and the predictions more precise so that
the emotional behavior that finally resulted would be adaptively
related to the stimulus event" (p 303). This model of the relationship
between emotion and cognition is somewhat similar to Bigelow's (1972),
which postulates that intelligence evolved as a result of the need to
control the emotions (especially the aggressive emotions), in the
service of sociality, and Humphrey's (1976, 1983), which claims that
self-awareness evolved because it was a successful tool for predicting
the behavior of others.
3. See Draper (1978) and the 1986 special issue of Ethology and
Sociobiology (vol. 7 #3/4) on ostracism for further discussion of the
role of shunning with specific reference to human societies; see
Hirshleifer & Rasmusen (1989) for a game theoretic model of shunning;
and see Nathanson (1992) for the importance of the social emotion,
4. The wealth of literature on strategies that people use to detect
deception in interpersonal interactions, as well as the technologies
that have been developed in order to further enhance that ability in
less-personal social interactions, are indicators of the importance we
bestow on such ability. (See Zuckerman, DePaulo & Rosenthal 1981,
Mitchell & Thompson 1986, and especially, Ekman 1992.)
5. Although the data are overwhelming, the particular articles cited
in this section should not be considered to be independent reports,
since most of the reviews cited overlap substantially in their
coverage, and many authors or teams report their findings more than
once in a series of updates. While interested readers should direct
themselves to the most recent publications, older publications do
contain some information not presented in the updates, and thus are
included for thoroughness and ease of reference.
6. Twin study methods yield estimates of what is termed "broad
heritability", which includes both "additive" genetic factors (i.e.,
the summed effect of individual genes on the phenotype) and "non-
additive" genetic factors (i.e., the phenotypic effects of dominance
interactions between homologous alleles on paired chromosomes, and the
epistatic interactions between non-homologous genes throughout the
genome). Adoption study methods, on the other hand, yield estimates of
what is termed "narrow heritability" which is only the additive
genetic component. The additive component is that which can be
selected for (or against) as it is transmitted from generation to
generation, while the nonadditive effect is unique to each individual
genotype and is broken and reshuffled with every episode of sexual
recombination. Because of this difference, twin studies typically
yield higher heritability estimates than adoption studies.
Another difference between the twin methodology and the adoption
methodology, is that twin studies generally provide heritability
coefficients which estimate the proportion of the total explained
variance accounted for by genetic factors, whereas adoption studies
provide heritability coefficients which estimate the proportion of the
total variance (including measurement error) that is accounted for by
additive genetic factors. Since measurement error is so large when
assessing criminality, adoption studies tend to yield both smaller and
more varied heritability estimates than do twin studies.
A third difference is that twin studies yield heritability estimates
for members of a particular generational cohort, usually tested at the
same age, whereas adoption studies necessarily regress measures from
one generation to another. This leads to two problems in interpreting
of heritability estimates derived from adoption studies which are not
germane to twin studies. The first is that heritability can change
across generations- even in the absence of genetic change- due to
changes in the environment; this effect cannot be assessed in either
twin or adoption studies, but is only a limitation of generalizability
for the former, whereas it is conflated in the latter. The second is
that heritability can also be different at different ages. Huesmann et
al (1984), for example, report that the correlation between children's
aggression level and their parents' aggression level when measured at
the same age, is greater than the correlation between the child's own
aggression level at one age and at a later age. This phenomenon, too,
results simply in limited generalizability of heritability estimates
derived from twin studies, but yields conflated estimates from
The heritability of .6 reported herein is an estimate of broad
heritability as derived directly from twin studies; similar estimates
can also be calculated indirectly from adoption study data after
accounting for measurement error, but cohort effects cannot be
separated out. See Loehlin (1992) for a general discussion of twin and
adoption methodologies and Emde et al (1992) and Raine (1993) for
further discussions of the relevance of methodological considerations
as they pertain to interpretation of the specific studies summarized
7. There is also evidence that at least one form of alcoholism belongs
to the sociopathy spectrum: Type II alcoholism, which is also much
more prevalent in men than women and seems to be transmitted in the
same way (Cloninger, Christiansen, Reich & Gottesman 1978, Bohman,
Sigvardsson & Cloninger 1981, Cloninger, Bohman & Sigvardsson 1981,
Stabenau 1985, Cadoret 1986, Zucker & Gomberg 1986, and McGue, Pickens
& Svikis 1992). Type II alcoholism is characterized by early onset,
frequent violent outbursts, EEG abnormalities, and several of the
personality attributes that are often seen in sociopathy- impulsivity,
extraversion, sensation- seeking, aggressiveness, and lack of concern
for others (Cloninger 1987b, Tarter 1988).
8. The interesting phenomenon of differential heritability of traits
across the sexes can occur, as in this case, as a result of
differential (sex-limited) expression of the same genes, or, as it
does with Type I alcoholism (a milder, nonviolent form), as a result
of differential environmental experiences of the sexes (Cloninger,
Christiansen, Reich & Gottesman 1978). Since heritability is measured
as a proportion, the value of a heritability estimate can be changed
by changes in either the numerator (variance in a trait due to genetic
variance) or the denominator (total variance in the trait). Since the
denominator (total variance) is composed of both genetic and
environmental variance, changes in either will change the
heritability. This method of defining heritability also explains some
other apparent paradoxes, such as how two populations (eg., racial
groups or two successive generations of a single group) could have
exactly the same genotypic variation with respect to a trait, but
because of differences in their environments, exhibit differential
phenotypes and differential heritability of the trait.
9. Like the behavior genetic studies cited in Section 2.1, these
studies provide overwhelming data, but should not be considered as
independent reports, because many overlap or update earlier work.
Methodologically, while path models and the longitudinal studies from
which they are derived have excellent ecological validity, they are
correlational, and while they improve upon cross-sectional designs by
noting which factors precede others developmentally, they cannot
completely sort out cause and effect- especially in the earliest
stages of parent-child interactions.
10. The strategy of sociopaths against one another, although not a
test of the current model, is still interesting in its own right. In
the Hare & Craigen (1974) modified Prisoner's Dilemma, the majority of
sociopaths, on their turn, chose from amongst five "plays", that
choice which minimized their own pain (an electric shock) for that
trial, but which maximized their partner's. Since partners took turns
in selecting from the same five "plays", this strategy actually
maximized pain over the long-run. The alternative, pain-minimizing
strategy, involved giving both oneself and one's partner a small
shock- a choice that most subjects declined to use. This result seems
to confirm the sociopath's inability to consider anything other than
the immediate consequences of an act, as well as the ineffectiveness
of delayed punishment or threat of punishment as a deterrent. In the
Widom (1976a) study, sociopaths did not, in general, "defect" more
often than the controls, but in the condition when subjects were
informed of their partner's move on the previous trial, sociopaths
were much more likely than controls to "defect" after a mutual
cooperation. On this measure, at least, the sociopaths seemed to
demonstrate an inability to "commit" to an ongoing cooperative
11. Terhune reports that personality is the most important factor for
strategy choice within the setting of single-trial Prisoner's Dilemma
interactions. In multiple-trial interactions, however, when players
have the opportunity to learn one another's dispositions, situational
factors are more important for determining play (see Frank, Gilovich &
Regan 1993). This is consistent with the idea that the establishment
of reputation is a key goal, even for players who on a single trial
would choose not to cooperate. For more on the idea that establishing
a certain reputation within one's referent group is a conscious goal,
and how that might play a role in the development of antisocial
behavior, see Hogan & Jones (1983) and Irons (1991).
12. For some of the debate on this issue see the series of comments
and replies following Nesse (1991) in the electronic journal
Psycoloquy. The comments specifically addressing the relationship
between mood and emotion are: Morris (1992), Nesse (1992a), Plutchik
(1992), and Nesse (1992b).
13. While searching for data to test this prediction, I came across
only the Robins et al (1991) reference in support of it, and one
reference in an introductory psychology text (Wade & Tavris 1993)
against it. The latter stated that antisocial personality disorder "is
rare or unknown in small, tight-knit, cooperative communities, such as
the Inuit, religious Hutterites, and Israelis raised on the communal
plan of the kibbutz" (p 584). Contact with Dr. Tavris allowed me to
follow up on the sources from which the latter statement was derived
(Eaton & Weil 1953, Montagu 1978, and Altrocchi 1980). My conclusion,
(which is shared by Dr. Tavris in a personal communication), is that
the absence or rarity of sociopathy in these small, tightly knit
societies, is not a result of the creation of a social system in which
sociopaths never develop; rather, it is that secondary sociopaths do
not develop (keeping total numbers at the low baseline), and that
primary sociopaths emigrate.
Small, closely knit societies have all the properties that game
theoretic models indicate will reduce (but not eliminate) the
incidence of the cheater strategy (see Section 3.2.1). One of the most
important of these features is size per se; the cheater strategy
cannot be used repeatedly against the same interactionists and remain
successful (see section 1.2). Thus, in small societies, sociopaths are
likely to do their damage, acquire a reputation, and leave- to avoid
punishment and move on to greener pastures. This "roving strategist"
model (Harpending & Sobus 1987, Dugatkin & Wilson 1991, Dugatkin 1992)
allows for both the evolution and the maintenance of a low baseline of
successful sociopaths even in small groups (like those in which we
14. Despite being a genetically based strategy, because primary
sociopathy is the end product of the additive and interactive effects
of many genes, we will not be able to predict or identify individual
sociopaths by knowledge of their genotype. We will, however, be able
to predict which children will be at risk, given their genetic
background, the same way we predict which children will be at risk
given their familial and sociocultural background. We will also be
alerted to differentiate between diagnoses of primary sociopathy and
secondary sociopathy (and our consequent approaches to them) based
upon knowledge of an already identified sociopath's genetic and
15. Axelrod (1986) and Boyd and Richerson (1992) also consider the
extension of punishment not only to cheaters, but to those cooperators
who do not, themselves, punish cheaters. The presence of this strategy
can lead to an ESS of practically any behavior, regardless of whether
there is any group benefit derived from such cooperation. Clearly this
extension of the model has some analogues with totalitarian regimes
and in-groups of a variety of sorts.
I would like to thank Mr. Rainer Link, who helped me get started on
this project, and who collaborated with me on the first version and
first public presentation of the model (Link & Mealey 1992). I would
also like to extend thanks to the many individuals who provided useful
comments during the revision process: J.D. Baldwin, David Buss,
Patricia Draper, Lee Dugatkin, Lee Ellis, Hans Eysenck, David
Farrington, Hill Goldsmith, Henry Harpending, James Kalat, John
Loehlin, Michael McGuire, Randy Nesse, Jaak Panskepp, David Rowe,
Sandra Scarr, Nancy Segal, Chuck Watson, David S. Wilson, and four
anonymous BBS reviewers.
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