I will present three sets of data concerning yawning in human and nonhuman
primates. First, the ability of adult male macaques to voluntarily control
the production of yawns will be described. This finding provides further
evidence that monkeys may co-opt reflexive acts into their communicatory
repertoire. Next, the development of contagious yawning in human children
will be shown. Surprisingly, children below the age of 5 years do not show
contagious yawning in situations known to induce the phenomenon in adults.
It is possible that individual difference in empathy are related to
readiness to show contagious yawning. Finally, I will introduce new data
showing contagious yawning in chimpanzees. Like humans, chimpanzees show
individual differences and a developmental change in this behaviour. I will
speculate on the implications of these findings for the phylogenetic
distribution of self-awareness and empathic ability.
(1) On reinforcement of yawning in male macaques:
Louboungou, M., & Anderson, J. R. (1987). Yawning, scratching, and
protruded lips: Differential conditionability of natural acts in pigtail
monkeys (Macaca nemestrina). Primates, 28, 367-375.
Anderson, J. R., & Wunderlich, D. (1988). Food-reinforced yawning in Macaca
tonkeana. American Journal of Primatology, 16, 165-169.
(2) On contagious yawning in children:
Anderson, J. R., & Meno, P. (2003). Psychological influences on yawning in
children. Current Psychology Letters: Behaviour, Brain & Cognition, 11 (2),
(3) On contagious yawning in chimpanzees:
Anderson, J. R., Myowa-Yamakoshi, M., & Matsuzawa, T. (2004). Contagious
yawning in chimpanzees. Proceedings of the Royal Society of London, Biology
Letters (in press).