McBrearty Sally, Jablonski Nina G
Department of Anthropology, University of Connecticut, Box U-2176, Storrs, Connecticut 06269, USA.
Nature. 2005 Sep 1;437(7055):105-8. doi: 10.1038/nature04008.
There are thousands of fossils of hominins, but no fossil chimpanzee has yet been reported. The chimpanzee (Pan) is the closest living relative to humans. Chimpanzee populations today are confined to wooded West and central Africa, whereas most hominin fossil sites occur in the semi-arid East African Rift Valley. This situation has fuelled speculation regarding causes for the divergence of the human and chimpanzee lineages five to eight million years ago. Some investigators have invoked a shift from wooded to savannah vegetation in East Africa, driven by climate change, to explain the apparent separation between chimpanzee and human ancestral populations and the origin of the unique hominin locomotor adaptation, bipedalism. The Rift Valley itself functions as an obstacle to chimpanzee occupation in some scenarios. Here we report the first fossil chimpanzee. These fossils, from the Kapthurin Formation, Kenya, show that representatives of Pan were present in the East African Rift Valley during the Middle Pleistocene, where they were contemporary with an extinct species of Homo. Habitats suitable for both hominins and chimpanzees were clearly present there during this period, and the Rift Valley did not present an impenetrable barrier to chimpanzee occupation.
人类化石有成千上万，但迄今尚未发现黑猩猩化石。黑猩猩（Pan）是现存与人类亲缘关系最近的物种。如今黑猩猩种群局限于西非和中非的森林地区，而大多数人类化石遗址则位于半干旱的东非大裂谷。这种情况引发了人们对500万至800万年前人类和黑猩猩谱系分化原因的猜测。一些研究人员认为，受气候变化影响，东非的植被从森林转变为稀树草原，这解释了黑猩猩和人类祖先种群之间明显的分离以及人类独特的两足行走运动适应方式的起源。在某些情况下，大裂谷本身成为黑猩猩生存的障碍。在此，我们报告首例黑猩猩化石。这些来自肯尼亚卡普图林组地层的化石表明，在中更新世时期，东非大裂谷地区存在黑猩猩代表物种，它们与一种已灭绝的人类物种同时存在。在此期间，那里显然存在适合人类和黑猩猩生存的栖息地，大裂谷并未对黑猩猩的生存构成不可逾越的障碍。
