miércoles, 9 de septiembre de 2015

Fishing for the first Americans



Archaeology is moving underwater and along riverbanks to find clues left by the people who colonized the New World.

On 17 September, a catamaran will set off into the Pacific Ocean on a week-long cruise back to the Pleistocene. Laden with sonar instruments, the research vessel Shearwater will probe the ocean bottom to find places that were beaches and dry land more than 13,000 years ago, when the sea level was around 100 metres lower. The researchers are hunting for evidence that ancient people lived along this now-sunken coastline as they colonized the New World.

Meanwhile, other archaeologists are digging in the intertidal zone on a remote island off the shore of British Columbia in Canada, where the sea level has barely changed since the ice-age glaciers began to retreat. Since late last year, that team has found footprints and a tool that date back 13,200 years, making them some of the oldest human marks on the continent. Whoever left them had to have reached the island by boat. Welcome to the newest wave of American archaeology: the idea that the first residents of the Americas came by sea, hugging the Pacific coast as they went south.[...] Nature News

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