[Paleopsych] SW: On Social Signals in Rodents

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Animal Behavior: On Social Signals in Rodents

    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:
    The following points are made by S.R. Dall (Current Biology 2004
    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
    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:
    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)
    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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