The first humans went to America earlier than was thought (4/16/2008)

With the aid of DNA analysis of 14,500-year-old feces, researchers have now been able to show that American Indians were present in America earlier than has long been thought

When and how America was populated has been a long drawn-out scientific debate. With the aid of DNA analysis of 14,500-year-old feces, Uppsala researchers in collaboration with Danish colleagues have now been able to show that American Indians were present in America earlier than has long been thought. The results of their research have been published in the American journal Science.

Researchers long thought that America was colonised relatively late - approx. 13,000 years ago. According to the theory, which goes under the name of Clovis First, the first humans would have arrived via an ice-free corridor crossing the area known as Beringia - from present-day eastern Siberia to Alaska. The theory took its name from the archaeological Clovis culture, to which the earliest remains have been deemed to belong. In recent years, however, researchers have questioned this scenario, partly because there is now reason to believe that the Clovis culture is perhaps not as old as was previously asserted, and partly because traces of humans have been found in America that may be over 13,000 years old.

"Completely discrediting the theory has nevertheless been hard, as the criticism of it is primarily based on controversial datings. But we have now succeeded, our study representing the last nail in the coffin for Clovis First," explains Anders Götherström from the Department of Evolutionary Biology, Uppsala University.

The study, which was headed by researchers from Copenhagen University and in which Uppsala researchers have played a crucial role, shows that humans were present in America thousands of years before the Clovis culture existed. The arguments are above all based on two types of data: C14 datings of fossilised feces (so-called coprolites) and DNA sequences found in them. The C14 datings show that the feces, which were found in the Paisley Caves in Oregon, are over 14,500 years old. The DNA analysis shows in turn that the feces are from American Indians.

"Our results push back the date of America's colonisation by at least a thousand years, though they in no way contradict the theory that the most important colonisation took place over Beringia," says Anders Götherström, who has himself worked on sequencing DNA from the prehistoric coprolites.

The study is a collaboration between researchers from Sweden, Denmark, the USA, Germany, Great Britain and Spain. The article has been published in the latest issue of Science Express, and will later appear as an ordinary article in Science.

Read the article in Science Express (PDF).

Note: This story has been adapted from a news release issued by the Uppsala University

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