Knuckling behavior in captive orangutans and a wounded baboon

Abstract With this communication we hope to clarify the usage of behavioral information from apparently non‐pathological orangutans and a pathological baboon to elucidate problems of hominoid locomotor evolution, particularly the problem of knuckle‐walking. We suggest that Hausfater's ('75) report on “knuckle walking” in the wounded baboon “Dutch” is at best marginally relevant to the problem of hominoid knuckle‐walking because Dutch is a pathological subject and because the report lacks quantification and sufficient descriptive detail to support the claim that his knuckling behavior is essentially the same as knuckle‐walking by extant African apes. Because we cannot observe the behavior of antecedent African apes and because of the relatively close morphological and genetic affinities of orangutans, chimpanzees, and gorillas, spontaneously knuckling and knuckle‐walking orangutans are the best available subjects to test certain hypotheses about the evolution of pongid knuckle‐walking.