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ScienceWeek
PSYCHOLOGY: ON LAUGHTER
The following points are made by Jaak Panksepp (Science 2005 308:5718):
1) Research suggests that the capacity for human laughter preceded the capacity for speech during evolution of the brain. Indeed, neural circuits for laughter exist in very ancient regions of the brain [1] and ancestral forms of play and laughter existed in other animals eons before we humans came along. Recent studies in rats, dogs, and chimps [2,3] are providing evidence that laughter and joy may not be uniquely human traits.
2) The capacity to laugh emerges early in child development, and perhaps in mammalian brain-mind evolution as well. Indeed, young children, whose semantic sense of humor is marginal, laugh and shriek abundantly in the midst of their other rough-and-tumble activities. If one looks carefully, laughter is especially evident during chasing, with the chasee typically laughing more than the chaser. As every aspiring comedian knows, success is only achieved if receivers exhibit more laughter than transmitters. The same behavior patterns are evident in the "play panting" of young chimps as they mischievously chase, mouth, and tickle each other [2].
3) Laughter seems to hark back to the ancestral emotional recesses of our animalian past [3,4]. We know that many other mammals exhibit play sounds, including tickle-induced panting, which resembles human laughter [2,4,5], even though these utterances are not as loud and persistent as our sonographically complex human chuckles. However, it is the discovery of "laughing rats" that could offer a workable model with which to systemically analyze the neurobiological antecedents of human joy [3]. When rats play, their rambunctious shenanigans are accompanied by a cacophony of 50-kHz chirps that reflect positive emotional feelings. Sonographic analysis suggests that some chirps, like human laughs, are more joyous than others.
4) Could sounds emitted by animals during play be an ancestral form of human laughter? If rats are tickled in a playful way, they readily emit these 50-kHz chirps [3]. The tickled rats became socially bonded to the experimenters and were rapidly conditioned to seek tickles. They preferred spending time with other animals that chirped a lot rather than with those that did not [3]. Indeed, chirping in rats could be provoked by neurochemically "tickling" dopamine reward circuits in the brain, which also light up during human mirth. Perhaps laughter will provide a new measure for analyzing natural reward/desire circuits in the brain, which are also activated during drug craving.
References (abridged):
1. K. Poeck, in Handbook of Clinical Neurology, P. J. Vinken, G. W. Bruyn, Eds. (North Holland, Amsterdam, 1969), vol. 3
2. T. Matsusaka, Primates, 45, 221 (2004)
3. J. Panksepp, J. Burgdorf, Physiol. Behav. 79, 533 (2003)
4. G. M. Burghardt, The Genesis of Animal Play (MIT Press, Cambridge, MA, 2005)
5. R. R. Provine, Laughter (Viking, New York, 2000)
Science http://www.sciencemag.org
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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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Related Material:
ON ANIMAL SELF-AWARENESS
The following points are made by Marc Bekoff (Nature 2002 419:255):
1) Researchers are interested in animal awareness because they are curious to discover what animals might know about themselves. There are, however, long-held and polarized views about the degree of self-awareness in animals. Some people believe that only great apes have "rich" notions of self --knowing who they are and/or having a "theory of mind", which means being able to infer the states of minds of others --whereas others argue that it is methodologically too difficult to address this question because animal (like human) minds are subjective and private. Many in this latter category do not attribute any sense of self to animals other than humans, and some, dismissing behavioral and neurobiological research on animal cognition, wonder whether animals are conscious of anything at all.
2) What might animals know about themselves? Most studies of animal self-awareness have been narrowly paradigm-driven. The "red spot" technique was first used by Gordon Gallup to study animal self-awareness in chimpanzees; it and variations have been used on great apes and monkeys, as well as on a few dolphins and elephants. For primates, a spot is placed on the forehead of an anesthetized individual and self-directed movements towards the spot are scored after he or she awakens and catches sight of themselves in a mirror, a high score indicating the presence of some degree of self-awareness. But in some cases, the data are derived from tests on small numbers of individuals, many of whom fail it because they do not make self-directed movements towards the spot. Those who pass the test might not be representative of wild relatives because they have had extensive human contact and previous experience with mirrors, factors that might influence their trainability and willingness to use a mirror. Those who fail the test might show some sense of 'self' in other contexts, and other individual differences might also play a role.
3) The concept of animal self-awareness remains open to different interpretations, but we will probably learn more about the mysteries of "self" and "body-ness" by using non-invasive neuroimaging techniques in combination with cognitive ethological studies. If we look at "self-awareness" as "body-awareness", we might also discover more about how animals think and the perceptual and neurobiological processes underlying various cognitive capacities. Darwin's ideas about evolutionary continuity, together with empirical data ("science sense") and common sense, caution against the unyielding claim that humans --and perhaps other great apes and cetaceans -- are the only species in which some sense of self has evolved.(1-5)
References (abridged):
1. Bekoff, M. Minding Animals: Awareness, Emotions, and Heart (Oxford Univ. Press, New York & London, 2002).
2. Bekoff, M., Allen, C. & Burghardt, G. M. (eds) The Cognitive Animal: Empirical and Theoretical Perspectives on Animal Cognition (MIT Press, Cambridge, Massachusetts, 2002); see especially essays on self-awareness by Gallup, G. G., Anderson, J. R. & Shillito, D. J.; Mitchell, R. W.; Shumaker, R. W. & Swartz, K. B.
3. Mitchell, R. W. in Handbook of Self and Identity (eds Leary, M. R. & Tangney, J.) 567 593 (Guilford, New York, 2002).
4. Reiss, D. Nature 418, 369 370 (2002).
5. Rilling, J. K. et al. Neuron 35, 395 405 (2002).
Nature http://www.nature.com/nature
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