Como a China está reescrevendo o livro da origem humana

quarta-feira, julho 13, 2016

How China is rewriting the book on human origins

Fossil finds in China are challenging ideas about the evolution of modern humans and our closest relatives.

Jane Qiu

12 July 2016

On the outskirts of Beijing, a small limestone mountain named Dragon Bone Hill rises above the surrounding sprawl. Along the northern side, a path leads up to some fenced-off caves that draw 150,000 visitors each year, from schoolchildren to grey-haired pensioners. It was here, in 1929, that researchers discovered a nearly complete ancient skull that they determined was roughly half a million years old. Dubbed Peking Man, it was among the earliest human remains ever uncovered, and it helped to convince many researchers that humanity first evolved in Asia.

Since then, the central importance of Peking Man has faded. Although modern dating methods put the fossil even earlier — at up to 780,000 years old — the specimen has been eclipsed by discoveries in Africa that have yielded much older remains of ancient human relatives. Such finds have cemented Africa's status as the cradle of humanity — the place from which modern humans and their predecessors spread around the globe — and relegated Asia to a kind of evolutionary cul-de-sac.

But the tale of Peking Man has haunted generations of Chinese researchers, who have struggled to understand its relationship to modern humans. “It's a story without an ending,” says Wu Xinzhi, a palaeontologist at the Chinese Academy of Sciences' Institute of Vertebrate Paleontology and Paleoanthropology (IVPP) in Beijing. They wonder whether the descendants of Peking Man and fellow members of the species Homo erectus died out or evolved into a more modern species, and whether they contributed to the gene pool of China today.

Keen to get to the bottom of its people's ancestry, China has in the past decade stepped up its efforts to uncover evidence of early humans across the country. It is reanalysing old fossil finds and pouring tens of millions of dollars a year into excavations. And the government is setting up a US$1.1-million laboratory at the IVPP to extract and sequence ancient DNA.

The investment comes at a time when palaeoanthropologists across the globe are starting to pay more attention to Asian fossils and how they relate to other early hominins — creatures that are more closely related to humans than to chimps. Finds in China and other parts of Asia have made it clear that a dazzling variety of Homo species once roamed the continent. And they are challenging conventional ideas about the evolutionary history of humanity.

“Many Western scientists tend to see Asian fossils and artefacts through the prism of what was happening in Africa and Europe,” says Wu. Those other continents have historically drawn more attention in studies of human evolution because of the antiquity of fossil finds there, and because they are closer to major palaeoanthropology research institutions, he says. “But it's increasingly clear that many Asian materials cannot fit into the traditional narrative of human evolution.”

Chris Stringer, a palaeoanthropologist at the Natural History Museum in London, agrees. “Asia has been a forgotten continent,” he says. “Its role in human evolution may have been largely under-appreciated.”