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Early Americans chomped on seaweed

Chewed-up or burned seaweed discarded more than 14,000 years ago confirm that people were in Chile at least that long ago and sheds light on what their culture was like, researchers report.

The findings at a site 16,000 kilometres from the Bering Strait add to an almost overwhelming pile of evidence that people were well distributed across the western Americas long before the so-called Clovis culture 13,000 years ago.

And the seaweed picked up at the Monte Verde site provides a direct link to people living in the area today, some of whom also use seaweed medicinally.

"What we have found ... are nine species of seaweed that are coming from rocky and sandy beaches located about 55 kilometres west of the site," says archaeologist Professor Tom Dillehay of Vanderbilt University in Nashville, who led the study published today in the journal Science.

"It indicates to us that the people of Monte Verde had a much stronger coastal industry than we thought previously. It indicates to us that we might be talking about people who initially entered into the Monte Verde site from the Pacific coastline itself," he says.

Controversial

The Monte Verde site 800 kilometres south of Santiago has long been controversial.

It was discovered in 1977 and its contents have been carbon-dated to more than 12,000 years ago, dates that careful calibration using tree rings and other information suggest are actually more than 14,000 years old.

This clashes with the one-time conventional wisdom that humans first crossed from Siberia using a land bridge over the Bering Strait about 13,000 years ago and then spread over the Americas.

But it supports newer genetic, linguistic and physical evidence that suggest this migration took place earlier, at least 16,000 years ago.

And it shows the upper layer of the site was occupied more than 1000 years earlier than any other reliably dated human settlements in the Americas.

Dillehay believes it supports his theory that early Americans moved slowly down the Pacific coast, learning about the local flora, fauna and other resources as they explored.

They would have moved inland a bit as they encountered raging, turbulent rivers full of melted snow from glaciers.

Older theories have focused on a human blitzkrieg, in which fast-moving groups spread over the continent quickly as they tracked and wiped out herds of big game.

Seaweed cakes

Some of the seaweed had been pressed into cakes and chewed as quids, like tobacco is sometimes today. Others had clearly been cooked, Dillehay and colleagues say.

"All nine seaweed species recovered at Monte Verde II are excellent sources of iodine, iron, zinc, protein, hormones, and a wide range of trace elements, particularly cobalt, copper, boron, and manganese," they write.

At least two of the species are used medicinally by local indigenous people to treat chest and intestinal ailments, Dillehay says.

He says it might be possible to take DNA from the chewed quids, but notes they are highly likely to have been contaminated since they were collected.

Last month, researchers reported they had analysed DNA from 14,000 year old human waste found in a cave in Oregon.