Meet the frail, small-brained people who first trekked out of Africa

Science magazine reports: On a promontory high above the sweeping grasslands of the Georgian steppe, a medieval church marks the spot where humans have come and gone along Silk Road trade routes for thousands of years. But 1.77 million years ago, this place was a crossroads for a different set of migrants. Among them were saber-toothed cats, Etruscan wolves, hyenas the size of lions—and early members of the human family.

Here, primitive hominins poked their tiny heads into animal dens to scavenge abandoned kills, fileting meat from the bones of mammoths and wolves with crude stone tools and eating it raw. They stalked deer as the animals drank from an ancient lake and gathered hackberries and nuts from chestnut and walnut trees lining nearby rivers. Sometimes the hominins themselves became the prey, as gnaw marks from big cats or hyenas on their fossilized limb bones now testify.

“Someone rang the dinner bell in gully one,” says geologist Reid Ferring of the University of North Texas in Denton, part of an international team analyzing the site. “Humans and carnivores were eating each other.”

This is the famous site of Dmanisi, Georgia, which offers an unparalleled glimpse into a harsh early chapter in human evolution, when primitive members of our genus Homo struggled to survive in a new land far north of their ancestors’ African home, braving winters without clothes or fire and competing with fierce carnivores for meat. The 4-hectare site has yielded closely packed, beautifully preserved fossils that are the oldest hominins known outside of Africa, including five skulls, about 50 skeletal bones, and an as-yet-unpublished pelvis unearthed 2 years ago. “There’s no other place like it,” says archaeologist Nick Toth of Indiana University in Bloomington. “It’s just this mother lode for one moment in time.”

Until the discovery of the first jawbone at Dmanisi 25 years ago, researchers thought that the first hominins to leave Africa were classic H. erectus (also known as H. ergaster in Africa). These tall, relatively large-brained ancestors of modern humans arose about 1.9 million years ago and soon afterward invented a sophisticated new tool, the hand ax. They were thought to be the first people to migrate out of Africa, making it all the way to Java, at the far end of Asia, as early as 1.6 million years ago. But as the bones and tools from Dmanisi accumulate, a different picture of the earliest migrants is emerging. [Continue reading…]

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