Shouldering the burden of evolution

A hypothesized model of shoulder shape evolution from African ape-like (top left) to modern human (bottom right)... Credit: Nathan Young

As early humans increasingly left forests and utilized tools, they took an evolutionary step away from apes. But what this last common ancestor with apes looked like has remained unclear. A new study led by researchers at UC San Francisco shows that important clues lie in the shoulder.

Humans split from our closest African ape relatives in the genus Pan -- including chimpanzees and bonobos -- 6 to 7 million years ago. Yet certain human traits resemble the more distantly related orangutan or even monkeys. This combination of characteristics calls into question whether the last common ancestor of modern humans and African apes looked more like modern day chimps and gorillas or an ancient ape unlike any living group. [...] sciencedaily.com/ / Link 2