[Paleopsych] Science Week: Animal Behavior: On Social Signals in Rodents
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Frank
Animal Behavior: On Social Signals in Rodents
http://scienceweek.com/2005/sw050527-2.htm
The following points are made by Leslie B. Vosshall (Current Biology
2005 15:R255):
1) Animals use odors to communicate precise information about
themselves to other members of their species. For instance,
domesticated dogs intently sample scent marks left by other dogs,
allowing them to determine the age, gender, sexual receptivity, and
exact identity of the animal that left the mark behind.[1,2] Social
communication in rodents is equally robust.[3-5] Male hamsters
efficiently choose new female sexual partners over old ones, a
phenomenon known as the "Coolidge Effect". The onset of estrus and
successful fetal implantation in female mice are both modulated by
male odors. Mice have the ability to discriminate conspecifics that
differ in MHC odortype and can determine whether others of their
species are infected by viruses or parasites, presumably a skill of
use in selecting a healthy mate.
2) Such social odors are typically produced in urine or secreted from
scent glands distributed over the body. Both volatile and non-volatile
cues are known to be produced. The accessory olfactory system,
comprising the vomeronasal organ and the accessory olfactory bulb,
responds largely to non-volatile cues, while the main olfactory system
receives volatile signals. Although mammalian pheromones are
classically thought to activate the accessory olfactory system,
several newly described pheromones are volatile and may act through
the main olfactory system. Chemical signals have a number of
advantages in social communication over signals that act on other
sensory modalities: they are energetically cheap to produce, often
being metabolic by-products; they are volatile and can therefore be
broadcast within a large territory; and they can continue to emit
signal after the animal has moved to a new location.
3) What are the specific, behaviorally active chemical signals present
in urine? What sensory neurons respond to these cues? Can a single
such compound be behaviorally active? A recent paper by Lin et al [6]
succeeds spectacularly in answering all three questions. The authors
applied chemistry, electrophysiology and behavior to this problem, and
identified biologically active volatiles in male urine that activate
both male and female main olfactory bulb mitral cells. They have
elucidated the chemical identity of a single such male-specific urine
component that both activates olfactory bulb mitral cells and elicits
behaviors in female mice. The new study builds on earlier work from
other laboratories that described regions in the olfactory bulb
activated upon exposure to whole mouse urine.
References (abridged):
1. Bekoff, M. (2001). Observations of scent-marking and discriminating
self from others by a domestic dog (Canis familiaris): tales of
displaced yellow snow. Behav. Processes 55, 75-79
2. Mekosh-Rosenbaum, V., Carr, W.J., Goodwin, J.L., Thomas, P.L.,
D'Ver, A., and Wysocki, C.J. (1994). Age-dependent responses to
chemosensory cues mediating kin recognition in dogs (Canis
familiaris). Physiol. Behav. 55, 495-499
3. Dulac, C. and Torello, A.T. (2003). Molecular detection of
pheromone signals in mammals: from genes to behavior. Nat. Rev.
Neurosci. 4, 551-562
4. Novotny, M.V. (2003). Pheromones, binding proteins and receptor
responses in rodents. Biochem. Soc. Trans. 31, 117-122
5. Restrepo, D., Arellano, J., Oliva, A.M., Schaefer, M.L., and Lin,
W. (2004). Emerging views on the distinct but related roles of the
main and accessory olfactory systems in responsiveness to chemosensory
signals in mice. Horm. Behav. 46, 247-256
6. Lin, D.Y., Zhang, S.Z., Block, E., and Katz, L.C. (2005). Encoding
social signals in the mouse main olfactory bulb. Nature 2005 Feb
20[Epub ahead of print] PMID: 15724148
Current Biology http://www.current-biology.com
--------------------------------
Related Material:
ANIMAL BEHAVIOR: ON ANIMAL PERSONALITIES
The following points are made by S.R. Dall (Current Biology 2004
14:R470):
1) Psychologists recognize that individual humans can be classified
according to how they differ in behavioral tendencies [1].
Furthermore, anyone who spends time watching non-human animals will be
struck by how, even within well-established groups of the same
species, individuals can be distinguished readily by their behavioral
predispositions. Evolutionary biologists have traditionally assumed
that individual behavioral differences within populations are
non-adaptive "noise" around (possibly) adaptive average behavior,
though since the 1970s it has been considered that such differences
may stem from competition for scarce resources [2].
2) It is becoming increasingly evident, however, that across a range
of taxa -- including primates and other mammals as well as birds,
fish, insects and cephalopod molluscs -- behavior varies non-randomly
among individuals along particular axes [3]. Comparative psychologists
and behavioral biologists [3-5] are documenting that individual
animals differ consistently in their aggressiveness, activity,
exploration, risk-taking, fearfulness and reactivity, suggesting that
such variation is likely to have significant ecological and
evolutionary consequences [4,5] and hence be a focus for selection.
From evolutionary and ecological viewpoints, non-random individual
behavioral specializations are coming to define animal personalities
[3], although they are also referred to as behavioral syndromes,
coping styles, strategies, axes and constructs [3-5].
3) The evolution of animal personality differences is poorly
understood. Ostensibly, it makes sense for animals to adjust their
behavior to current conditions, including their own physiological
condition, which can result in behavioral differences if local
conditions vary between individuals. It is unclear, however, why such
differences should persist when circumstances change. In fact, even in
homogenous environments interactions between individuals can favor the
adoption of alternative tactics. For instance, competition for
parental attention in human families may encourage later-born children
to distinguish themselves by rebelling. In the classic Hawk Dove game
model of animal conflicts over resources, if getting into escalated
fights costs more than the resource is worth, a stable mix of pacifist
(dove) and aggressive (hawk) tactics can evolve. This is because, as
hawks become common, it pays to avoid fighting and play dove, and vice
versa.
4) There are, however, two ways in which evolutionarily stable
mixtures of tactics can be maintained by such frequency-dependent
payoffs: individuals can adopt tactics randomly with a fixed
probability that generates the predicted mix in a large population;
alternatively, fixed proportions of individuals can play tactics
consistently. Only the latter would account for animal personality
differences. It turns out that consistent hawks and doves can be
favored if the outcomes of fights are observed by future opponents and
influence their decisions --being persistently aggressive will then
discourage fights, as potential opponents will expect to face a costly
contest if they challenge for access to the resource. At least in
theory, therefore, personality differences can evolve when the fitness
consequences of behavior depend both on an individual's behavioral
history and the behavior of other animals.
References (abridged):
1. Pervin, L. and John, O.P. (1999). Handbook of Personality. (:
Guilford Press)
2. Wilson, D.S. (1998). Adaptive individual differences within single
populations. Philos. Trans. R. Soc. Lond. B Biol. Sci 353, 199-205
3. Gosling, S.D. (2001). From mice to men: what can we learn about
personality from animal research. Psychol. Bull. 127, 45-86
4. Sih, A., Bell, A.M., Johnson, J.C. and Ziemba, R.E. (2004).
Behavioral syndromes: an integrative review. Q. Rev. Biol. in press.
5. Sih, A., Bell, A.M. and Johnson, J.C. (2004). Behavioral syndromes:
an ecological and evolutionary overview. Trends Ecol. Evol. in press.
Current Biology http://www.current-biology.com
--------------------------------
Related Material:
ANIMAL BEHAVIOR: ON ANTHROPOMORPHISM
The following points are made by Clive D. Wynne (Nature 2004 428:606):
1) The complexity of animal behavior naturally prompts us to use terms
that are familiar from everyday descriptions of our own actions.
Charles Darwin (1809-1882) used mentalistic terms freely when
describing, for example, pleasure and disappointment in dogs; the
cunning of a cobra; and sympathy in crows. Darwin's careful
anthropomorphism, when combined with meticulous description, provided
a scientific basis for obvious resemblances between the behavior and
psychology of humans and other animals. It raised few objections.
2) The 1890s saw a strong reaction against ascribing conscious
thoughts to animals. In the UK, the canon of Conwy Lloyd Morgan
(1852-1936) forbade the explanation of animal behavior with "a higher
psychical faculty" than demanded by the data. In the US, Edward
Thorndike (1874-1949) advocated replacing the use of anecdotes in the
study of animal behavior with controlled experiments. He argued that
when studied in controlled and reproducible environments, animal
behavior revealed simple mechanical laws that made mentalistic
explanations unnecessary.
3) This rejection of anthropomorphism was one of the few founding
principles of behaviorism that survived the rise of ethological and
cognitive approaches to studying animal behavior. But after a century
of silence, recent decades have seen a resurgence of anthropomorphism.
This movement was led by ethologist Donald Griffin, famous for his
discovery of bat sonar. Griffin argued that the complexity of animal
behavior implies conscious beliefs and desires, and that an
anthropomorphic explanation can be more parsimonious than one built
solely on behavioral laws. Griffin postulated, "Insofar as animals
have conscious experiences, this is a significant fact about their
nature and their lives." Animal communication particularly impressed
Griffin as implying animal consciousness.
4) Griffin has inspired several researchers to develop ways of making
anthropomorphism into a constructive tool for understanding animal
behavior. Gordon Burghardt was keen to distinguish the impulse that
prompts children to engage in conversations with the family dog (naive
anthropomorphism) from "critical anthropomorphism", which uses the
assumption of animal consciousness as a "heuristic method to formulate
research agendas that result in publicly verifiable data that move our
understanding of behavior forward." Burghardt points to the
death-feigning behavior of snakes and possums as examples of complex
and apparently deceitful behaviors that can best be understood by
assuming that animals have conscious states.
5) But anthropomorphism is not a well-developed scientific system. On
the contrary, its hypotheses are generally nothing more than informal
folk psychology, and may be of no more use to the scientific
psychologist than folk physics to a trained physicist. Although
anthropomorphism may on occasion be a source of useful hypotheses
about animal behavior, acknowledging this does not concede the general
utility of an anthropomorphic approach to animal behavior.(1-4)
References:
1. Blumberg, M. S. & Wasserman, E. A. Am. Psychol. 50, 133-144 (1995)
2. De Waal, F. B. M. Phil. Top. 27, 255-280 (1999)
3. Mitchell, R. W. et al. Anthropomorphism, Anecdotes and Animals
(State Univ. New York Press, New York, 1997)
4. Wynne, C. D. L. Do Animals Think? (Princeton Univ. Press,
Princeton, New Jersey, 2004)
Nature http://www.nature.com/nature
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