Bone points to new look at human migration
It’s only 3 centimeters long and less than 1 centimeter wide, but it has the potential to rewrite the history of our ancestors’ migration out of Africa.
The object in question is a fossilized piece of a bone, probably the middle portion of a middle finger. Based on its shape, scientists believe that it belonged to a member of the Homo sapiens species.
Two things make it unusually significant. First, uranium series dating techniques indicate that the bone is 85,000 to 90,000 years old.
Second, it was found in Al Wusta, a site in Saudi Arabia’s Nefud desert that’s hundreds of miles from the nearest coastline.
Those factors stand in sharp contrast to the traditional “out of Africa” narrative of human migration.
Based on both archaeological evidence and genetic analysis, this theory posits that modern humans left their home continent about 60,000 years ago and stayed near the coasts as they spread out across the world.
Recent recent discoveries have poked holes in this story. Scientists have found what appear to be Homo sapiens teeth in Chinese caves that suggest humans arrived there much earlier.
In the Fuyan Cave, for instance, teeth were found among mineral deposits that were at least 80,000 years old. In the Luna Cave, more teeth were uncovered among material that is believed to be 130,000 to 70,000 years old.
In Australia, archaeologists turned up 65,000-yearold stone tools and other artifacts that suggest humans had reached the northern part of the continent by then.
Michael Petraglia of the Max Planck Institute for the Science of Human History in Jena, Germany, says ancient people probably left Africa through the Arabian Peninsula.
He and others report the Al Wusta discovery Monday in the journal Nature Ecology & Evolution.
The finger bone from Al Wusta, however, marks the first time scientists have tested the age of a human fossil from so far beyond Africa and found it to be significantly older than 60,000 years.
The finger bone wasn’t the only find at the site.
Team members also unearthed hundreds of animal fossils, including hippopotamuses, antelope and extinct species of African wild cattle.
“These animals tell us that when humans were living there, it was not a desert,” said first author Huw Groucutt, an archaeologist at the University of Oxford. Instead, monsoon rains had transformed the area into a grassland with freshwater lakes and rivers. “There were abundant animals and a lot of people living there,” Groucutt said.