Earliest Known American Settlers Harvested Seaweed

Stefan Lovgren
for National Geographic News
May 8, 2008
People living in the earliest known settlement in the Americas harvested seaweed and other marine plants from a coastline more than 50 miles (80 kilometers) away, new research shows.

Scientists discovered several species of seaweed and marine algae dating back more than 14,000 years at the Monte Verde archaeological site in south-central Chile.

The findings suggest that these early Americans were beachcombers with a tradition of using coastal resources, says study lead author Tom Dillehay.

"At least some first Americans had a broad spectrum diet, because we're seeing that they exploited a wide range of resources from multiple environmental zones—terrestrial, coastal, and so forth," said Dillehay, an anthropologist at Tennessee's Vanderbilt University.

The results, which will appear in tomorrow's issue of the journal Science, also support the theory that the first Americans spread through the New World along a coastal route after walking across a land bridge from Asia to Alaska at least 15,000 years ago.

(See an interactive map of ancient human migration.)

Rising Sea Levels

The discovery of a human settlement at Monte Verde in the mid-1970s provided the first evidence that people had inhabited the Americas before the spread of the so-called Clovis culture around 13,000 years ago.

Scientists were long mystified how people could have reached the southern tip of South America without leaving much evidence along the way.

But many now believe the first Americans spread down the coast where they could exploit the sea for food.

(Read related story: "First Americans Arrived Recently, Settled Pacific Coast, DNA Study Says" [February 2, 2007].)

The lack of archaeological evidence of this migration may be due to rising sea levels.

At the time sea levels were about 200 feet (61 meters) lower than they are today, and many of the early coastal settlements may now be underwater.

Ancient Monte Verde was situated on a small tributary of a large river, and sat more than 50 miles (80 kilometers) from the coast and about 10 miles (16 kilometers) from a large marine bay.

The site has well-preserved ruins of a small settlement that likely supported 20 to 30 people living in a dozen huts.

Many types of food, including extinct species of llama, have been found at the site.

When Dillehay and his colleagues first excavated the site in 1979, they found several species of seaweed there. (The excavation was partially funded by the National Geographic Society, which owns National Geographic News.)

"This indicated that people living inland had occasionally gone to the coast to exploit marine beach resources," Dillehay said.

"But we didn't give it much thought. We thought it was just one component of their economic realms."

Seaweed Medicine?

When they went back to analyze material collected in the 1980s, the scientists identified nine species of marine algae recovered from hearths and other cooking features at the site, suggesting the people living there ate the plants.

Using radiocarbon dating, they dated the seaweed samples to between 14,220 to 13,980 years old.

The scientists found pieces of seaweed mixed with other plants and chewed into clumps, possibly for medicinal purposes.

They also found a stone cutting tool with seaweed stuck to the blade.

"Seaweed is difficult to preserve, which means we're just looking at a fraction of what the seaweed contribution to the diet probably was," Dillehay said.

The Monte Verdeans' familiarity with the coast suggests that they may have initially migrated down the coast and perhaps spent some time there before moving inland, he said.

Slower Migration?

Michael Waters is the director of the Center for the Study of the First Americans at Texas A&M University.

"The new evidence from the Monte Verde site confirms its status as the earliest known human settlement in the Americas and provides additional support for the theory that one early migration route followed the Pacific Coast more than 14,000 years ago," he said.

But Dillehay says the coastal migration may have been slower than is commonly believed.

The discovery of plentiful inland resources at the Monte Verde site, including meat from an elephant-like animal called gomphothere, suggests that the people living there moved back and forth between different ecological zones, he noted.

That kind of movement takes considerable time to adapt to, he explained.

"If Monteverde is indicative of what some early migrants are doing, then I think this migration down the coastline may not have been this blitzkrieg movement" that many scientists suggest, he said.

"It may have been a much slower movement of people exploiting simultaneously coastal and river resources."

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