Tools and mastodon bones point to man’s earlier arrival in the Americas

San Diego fossils suggest presence 130,000 years ago

WASHINGTON // Researchers have found stone tools and broken mastodon bones in California that show humans reached the Americas about 130,000 years ago – far earlier than previously known.

They called the five rudimentary hammerstones and anvils found in San Diego County, with fossil bones from the prehistoric elephant, compelling evidence that they could have been Homo sapiens or an extinct species such as Neanderthals.

San Diego Natural History Museum palaeontologist Tom Demere said that until now, the oldest widely accepted date for human presence in the New World was 14,000 to 15,000 years ago, making the San Diego site nearly 10 times older.

The finding would radically rewrite the understanding of when humans reached the New World.

“If the date of 130,000 years old is genuine, then this is one of the biggest discoveries in American archaeology,” said University of Southampton palaeontologist John McNabb, who was not involved in the research and said he was still a little sceptical. No human skeletal remains were found but wear and impact marks on the stone tools and the way in which mastodon limb bones and molars were broken, apparently just after the animal’s death, convinced the researchers that humans were responsible.

They conducted experiments using comparable tools on elephant bones and produced similar fracture patterns.

“People were here breaking up the limb bones of this mastodon, probably to make tools out of, and they may have also been extracting some of the marrow for food,” said archaeologist Steven Holen of the Centre for American Paleolithic Research in South Dakota.

US Geological Survey geologist James Paces used state-of-theart dating methods to determine the mastodon bones, tooth enamel and tusks were 131,000 years old, plus or minus about 9,000 years.

Some sceptics suggested the bones may have been broken recently by heavy construction equipment.

The researchers defended their conclusions, published in the journal Nature.

“It’s hard to argue with the clear and remarkable evidence that we can see in all of this material,” said archaeologist Richard Fullagar of Australia’s University of Wollongong.

Homo sapiens first appeared in Africa about 200,000 years ago and later spread worldwide.

Timing of the New World arrival has been contentious. Genetic data suggests it was about 23,000 years ago, although evidence is lacking. Mr Holen said humans may have walked from Siberia to Alaska on a now- gone Bering Sea land bridge or travelled by boat along the Asian coast, then over to Alaska and down North America’s western coastline to California.

“It’s a huge deal if it’s true,” Mr McNabb said.

But he wondered whether anything else could have produced the impact and damage patterns on the material other than humans.