1. Goodall J (1986) The chimpanzees of Gombe: patterns of behavior. Harvard University Press, Cambridge, Mass.
2. Hiraiwa-Hasegawa M (1990a) A note on the ontogeny of feeding. In: Nishida T (ed) The chimpanzees of Mahale mountains. Tokyo University Press, Tokyo, pp 279?283
3. Hiraiwa-Hasegawa M (1990b) Role of food sharing between mother and infant in the ontogeny of feeding behavior. In: Nishida T (ed) The chimpanzees of Mahale mountains. Tokyo University Press, Tokyo, pp 267?275
4. King BJ (1994) The information continuum?evolution of social information transfer in monkeys, apes, and hominids. School of American Research Press, Santa Fe, N.M.
5. Lefebvre L (1985) Parent?offspring food sharing: a statistical test of the early weaning hypothesis. J Hum Evol 14:255?261