Clayton, N. S., and A. Dickinson. 1998. Episodic-like memory during cache recovery by scrub jays. Nature 395:272–74.
Coan, J. A., H. S. Schaefer, and R. J. Davidson. 2006. Lending a hand: Social regulation of the neural response to threat. Psychological Science 17:1032–39.
Coe, C. L., and L. A. Rosenblum. 1984. Male dominance in the bonnet macaque: A malleable relationship. In Social Cohesion: Essays Toward a Sociophysiological Perspective, ed. P. R. Barchas and S. P. Mendoza, 31–63. Westport, CT: Greenwood.
Cordain, L., et al. 2000. Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets. American Journal of Clinical Nutrition 71:682–92.
Crick, F. 1995. The Astonishing Hypothesis: The Scientific Search for the Soul. New York: Scribner.
Curtis, V. A. 2014. Infection-avoidance behaviour in humans and other animals. Trends in Immunology 35:457–64.
Custance, D., and J. Mayer. 2012. Empathic-like responding by domestic dogs (Canis familiaris) to distress in humans: An exploratory study. Animal Cognition 15:851–59.
Damasio, A. R. 1994. Descartes’ Error: Emotion, Reason, and the Human Brain. New York: Putnam.
–. 1999. The Feeling of What Happens: Body and Emotion in the Making of Consciousness. New York: Harcourt.
Darwin, C. 1987. The Correspondence of Charles Darwin, vol. 2: 1837–1843. Ed. F. Burkhardt and S. Smith. Cambridge: Cambridge University Press.
–. 1998 [orig. 1872]. The Expression of the Emotions in Man and Animals. New York: Oxford University Press.
Davila Ross, M., S. Menzler, and E. Zimmermann. 2007. Rapid facial mimicry in orangutan play. Biology Letters 4:27–30.
de Montaigne, M. 2003 [orig. 1580]. The Complete Essays. London: Penguin.
de Waal, F. B. M. 1982. Chimpanzee Politics. London: Jonathan Cape.
–. 1986. The brutal elimination of a rival among captive male chimpanzees. Ethology and Sociobiology 7:237–51.
–. 1989. Peacemaking Among Primates. Cambridge, MA: Harvard University Press.
–. 1997a. The chimpanzee’s service economy: Food for grooming. Evolution and Human Behavior 18:375–86.
–. 1997b. Bonobo: The Forgotten Ape. Berkeley: University of California Press.
–. 2007 [orig. 1982]. Chimpanzee Politics: Power and Sex among Apes. Baltimore: Johns Hopkins University Press.
–. 2008. Putting the altruism back into altruism: The evolution of empathy. Annual Review of Psychology 59:279–300.