Scientists locate first human home

The major features of the Kalahari Desert in southern Africa are shimmering salt pans and endless sand.

Yet this barren region, which covers parts of Botswana, Namibia and Zimbabwe, is where a group of Australian scientists now believe we come from.

They claim to have discovered the birthplace of modern humans at a former lake – Lake Makgadikgadi.

Rewind 200,000 years and the Kalahari Desert was covered by a vast system of lakes and wetlands. It would have supported birds and animals and, somewhere along its shores, a small band of humans.

These humans were the ancestors of people today, the scientists claim in a study published on Tuesday in the journal Nature.

The remarkable potential discovery of the ancestral homeland of modern humans is being hailed as a new chapter in the story of us.

‘‘We have rewritten our human history,’’ says Professor Vanessa Hayes, the Sydney-based academic who led the study.

Scientists have known for a long time that the DNA of all races around the world can be traced to Africa. Hayes was part of the first team to sequence the full DNA, known as the genome, of five indigenous Africans.

‘‘Europeans and Asians today are so related to each other,’’ she says. ‘‘We went through such a major genetic bottleneck when we left Africa. All we have been doing is studying a very tiny branch of a very big genetic tree.’’

After that work was published, Hayes continued sequencing DNA from indigenous groups in Africa, splitting her time between the Kalahari and her bases at Australia’s Garvan Institute and the University of Sydney.

She followed the trail

of mitochondrial DNA, which is passed on unchanged from a mother to her child, with the hope of tracing the thread back to our earliest female ancestors.

That led her first to the Kalahari Desert, and then to the Khoesan (pronounced koh sahn) people, a group identified through their use of a clicking language. ‘‘They represent a lineage that never left the homeland,’’ Hayes says.

She spent time with one Khoesan group, the Ju/’hoansi. They live as hunter-gatherers, just as their ancestors did.

When she told them their DNA

Professor Vanessa Hayes learns how to make fire with Ju/’hoansi hunters in the now dried homeland of the greater Kalahari of Namibia suggested their people were the ancestors of modern humans, they were not surprised. Their oral histories record them living in the area forever.

‘‘They know they have always been there,’’ says Professor Hayes.

Today the Kalahari is dry. But hundreds of thousands of years ago, according to climate modelling, the region was lush, humid, and dominated by Lake Makgadikgadi, a giant lake twice the size of Africa’s Lake Victoria.

As modern humans started to emerge, Makgadikgadi was breaking up into a series of smaller wetlands which would have teemed with life; ‘‘a perfect oasis for modern humans to live’’, says Hayes.

Around the was dry.

But 130,000 years ago changes in the Earth’s climate would have brought warmth and rain to a corridor that ran from the wetland north-east towards the coast. That would have provided food and water for some members of the group to migrate.

These were the people who would learn to traverse water and later sail to conquer the rest of the world.

It is a neat and comprehensive origin story.

But David Lambert, a leading human evolution and indigenous DNA researcher at the Australian Research Centre for Human Evolution, fears the evidence is not strong enough to back up the claims.

‘‘The authors themselves are slightly cautious about it. Nature is very good at selling what they have got,’’ he says.

In a press release put out with the study, Nature claims the research pinpoints the ancestral homeland of all humans.

But the last paragraph of the paper notes the evidence cannot rule out the possibility modern humans evolved at similar times in different spots across Africa before interbreeding. – Nine

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