The lack of fossils had forced scientists to make complicated hypotheses about how apes emerged in Africa 22 million years ago, migrated to Europe and Asia, disappeared from Africa, migrated back in Africa from Europe and from that lineage humans, chimps and gorillas appeared.
But a new 10-million-year old jaw bone and 11 teeth
found in the eastern edge of the Kenyan Rift Valley of Kenya simplifies this entangled theory and shows that the common ancestors of humans, chimpanzees and gorillas were local Africans, not migrating from Europe or Asia.
DNA revealed that humans and chimpanzees split 4 to 5 million years ago, but the fossils proving this have been scarce. And before 7 million years ago gorillas had split from this branch. But researchers had not encountered African ape fossils 7 to 12 million years old, a fact that made some coming with the idea that apes had gone extinct in Africa by those times.
The new ape species, the second one found from Africa of those times, described in the Proceedings of the National Academy of Sciences shatters this theory.
Nakalipithecus nakayamai, found in Nakali, Kenya, in 2005, was located less than 30 km (19 mi) from the Samburu area where another recently discovered ape, Samburupithecus kiptalami lived 9.6 million years ago.
"The discovery of Nakalipithecus shows that there were two different large hominoids even within a very narrow range of time and space in the early late Miocene of Kenya," said lead author Yutaka Kunimatsu, a paleoanthropologist at Kyoto University in Japan.
But while Samburupithecus seems to have been a co-lateral branch in human evolution, Nakalipithecus could have been closely related to the last common ancestor of humans, chimpanzees and gorillas. Another 10-million-year-old ape, recently discovered in Ethiopia, Chororapithecus abyssinicus, could have been close to the first gorillas, or at least led a life very similar to that of modern gorillas. This new array of fossils shows that our ancestors never vanished from Africa.
"The gap in the fossil record for Miocene apes in Africa may exist because few people have looked for apes in the right time and place in Africa--or that many of the apes lived in wooded habitats where their remains were less likely to fossilize in acidic soils." said paleoanthropologist Andrew Hill of Yale University.
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