How times have changed. Instead of large amounts of meat and spuds, some of the first Americans enjoyed healthy doses of seaweed.
The evidence comes from 27 litres of material collected from the Monte Verde site in southern Chile, widely accepted as the oldest settlement in the Americas. Nine species of seaweed, carbon dated at 13,980 to 14,220 years old, played a major role in a diet that included land plants and animals.
Tom Dillehay of Vanderbilt University in Nashville, Tennessee, argues that the seaweeds were used both as food and medicine. Some were found in remains of ancient hearths and others had been chewed into clumps, or "cuds," which may have been used for medicinal purposes. Indigenous people still use the same species medicinally.
Several of the seaweed species seem to have come from a rocky marine bay that was about 15 kilometres south of the ancient settlement, but three other types are found only on sandy open-ocean shores that, at the time, were 90 km west of the site.
The choice of seaweeds, and local land plants also identified at the site, show that the residents had good knowledge of both coastal resources and foods from the interior, which allowed them to stay in the region year-round, concludes Dillehay, who has studied Monte Verde for three decades.
The most widely accepted theory holds that early Americans came from Asia across the Bering land bridge, eventually reaching South America. Dillehay says Monte Verde was a logical place to settle.
"It has one of the highest densities of economic resources for hunter gatherers in the world," he says.
Groups moving along the Pacific coast may have done so much more slowly than has been assumed. As they migrated southwards, people exploited the interior resources of the hundreds of river basins descending from near-coast mountain ranges, Dillehay and colleagues suggest.
"If all the early American groups were following a similar pattern of moving back and forth between inland and coastal areas, then the peopling of the Americas may not have been the blitzkrieg movement that people have presumed, but a much slower and more deliberate process," says Dillehay.
Some theories hold that humans also migrated out of Africa to East Asia and Australia along coasts.
However the discovery at Monte Verde of plant remains from the Andes shows that the settlers did not just come down the coast, says David Meltzer of Southern Methodist University in Dallas, Texas.
"They are getting their resources from a wide range of environments," he says. Meltzer adds that recent reports of slightly younger remains from Paisley Caves in Oregon shows that some people were going much further inland.
But the most intriguing - and still unanswered - question is how those early Americans were related to the Clovis people who spread explosively across interior North America around 13,000 years ago.
Journal reference: Science (DOI: 10.1126/science.1156533)
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