The observation of cooperative hunting and food sharing behavior in rainforest chimps questions the generally accepted theory that hominid evolution is linked to the drying of the environment and the change of habitat from dense forests to open savannahs. It questions the theory that it was savannah life which led to the evolution of complex hominid behavior.
Boesch and Achermann support their argument by citing their observations of the hunting and sharing behavior of the Tai rainforest chimps, and comparing this with Jane Goodall’s observation of the savannah chimps at Gombe. Group hunting comprises 92% of rainforest chimps’ hunting, while savannah chimps demonstrate only 36% of group hunting. Even in the event of group hunting, rainforest chimps coordinate their behavior 63% of the time, while savannah chimps coordinate their group hunting behavior only in 7% of cases. Likewise, food sharing is more prevalent among the rainforest chimps than the savannah chimps. Again, the Tai chimps show nineteen different ways of tool usage and six different ways of methods of tool manufacture, in comparison with sixteen different uses and three methods of manufacture in savannah chimps.
The authors address the claim of anthropologists who state that it was the transformation of rainforests into dry, open savannahs, due to climate change, which began the process of hominization and the hypothesis that it was the difficulties of savannah life which resulted in the evolution of more complex behavior, and a hominid evolution distinct from that of rainforest primates. Boesch and Achermann counter the above claim by arguing that, to the contrary, it is rainforest chimps who demonstrate more complex skills in hunting and in the usage of tools and in the overall sophistication of their behavior.
The authors’ arguments rest on the must-be-acknowledged strength of their documented, first-hand observation of rainforest chimps, in