Introduction

Despite more than 30 years of study of free-living chimpanzees in their African habitat, there is no firm agreement as to the social organization of this species. Both ‘naturalistic’ (unobtrusive) and ‘provisioning’ (artificially feeding) methods of field study have been used, with sharply differing results. Independent field researchers, using various naturalistic methods report – quite separately but with striking unanimity – peaceful, open groups of nonaggressive chimpanzees without signs of any dominance hierarchy, enforced territoriality or single leaders.

At the long-established, permanent centers for the study of free chimpanzees in Gombe and Mahale National Parks, Tanzania, artificial feeding methods have been used. Researchers at both centers – also quite separately – report many strongly similar aspects of behavior and social organization of the provisioned apes that are opposite to reports from naturalistic studies. The artificially fed Gombe and Mahale apes are extremely aggressive, dominance seeking, directly competitive and fiercely territorial.

Habituating the apes to the presence of humans through provisioning facilitates excellent, lengthy observation opportunities, an intimate knowledge of the chimpanzees as interacting individuals, and a large pool of data. Naturalistic studies do not have these advantages. Consequently, not only are our current understandings of chimpanzee social behavior and organization based very largely on the Gombe and Mahale studies but also there is a tendency to assume that the noncontinuous naturalistic studies yield few or no data on the social behavior and organization of chimpanzees. Washburn (1980:258) expresses the view of many when he asserts that ‘the beginning of reliable studies’ on the natural behavior of chimpanzees may be marked by ‘Jane Goodall's (1968) long-continued investigations’ (my emphasis).