Team of Australian-led geneticists say they have found birthplace of modern humans

A team of Australian-led geneticists say they have pinpointed exactly where the first humans came from.

About 200,000 years after humans first arose in Africa, a team of Australian-led geneticists believe they may be able to pinpoint where exactly those first humans came from. Picture: iStock

Some 130,000 years ago the Earth wobbled on its axis and shifted in its orbit around the Sun. According to a new investigation of our origins, this celestial realignment allowed our forebears to venture beyond their “ancestral homeland” for the first time.

The most elaborate genetic study of its kind has concluded that the roots of all humans alive today can be traced back to an ancient oasis that once lay south of the Zambezi River, in what is now northern Botswana.

The analysis suggests that 200,000 years ago this region consisted of lakes and wetlands, where a “founder population” of hunter-gatherer Homo sapiens gained a foothold.

For 700 centuries, they were encircled by arid, impenetrable desert. As Earth’s orbit shifted at the end of the penultimate Ice Age, 130,000 years ago, the climate of southern Africa became warmer and wetter. Corridors of vegetation opened, first to the northwest and later to the southeast.

For the first time, the researchers contend, modern man was on the move.

“It has been clear for some time that anatomically modern humans appeared in Africa roughly 200,000 years ago. What has been long debated is the exact location of this emergence and the subsequent dispersal of our earliest ancestors,” Vanessa Hayes of the Garvan Institute in Sydney, a co-author of a paper published yesterday in the journal Nature, said. She added: “We describe the first human exploration.”

 

The research, which studied the DNA of modern Africans to infer our ancient lineage, is the most extensive of its kind but immediately drew fire from rival researchers. For years, scientists have been split on where in Africa modern humans first appeared. It was thought to be in the Rift Valley of east Africa until more ancient remains were found in Morocco two years ago.

Chris Stringer of the Natural History Museum in London, who was not involved in the new study, cautioned that our African roots are not fully understood. It was likely that we have “an amalgam of ancestry from different regions of Africa with, of course, the addition of interbreeding from other human groups outside the continent,” he said. “I’m cautious about using modern genetic distributions to infer exactly where ancestral populations were living 200,000 years ago, particularly in a continent as large and complex as Africa.”

The new study examined mitochondrial DNA, which is passed down only from mothers to their children. Hundreds of samples from people living in southern Africa were collected. These were compared with a broader DNA database to build a map of the earliest ancestral branches of modern man. The results suggest that we all share an ancient maternal lineage, known as the L0 lineage, that can be traced back to the shores of Lake Makgadikgadi, a body of water that was once as large as New Zealand but which had begun to fragment by the time Homo sapiens emerged.

Our ancestors migrated out of this “homeland” between 130,000 and 110,000 years ago, Professor Hayes said. “The first migrants ventured northeast, a second wave travelled southwest. A third population remained in the homeland until today.” She recently spoke to some of those living in this region. They were not surprised by her findings. “They told me, ‘We know we’ve always been here,’” she said.

THE TIMES