Humankind's ancestral 'homeland' pinpointed in Botswana

It has been clear for some time that anatomically modern humans appeared in Africa roughly 200,000 years ago

It has been clear for some time that anatomically modern humans appeared in Africa roughly 200,000 years ago

The evolutionary history of humans is a murky one that's full of gaps, but now researchers from Australia and South Africa claim to have plugged one of these plot holes. The researchers' findings imply that ancient humans thrived because of the wetlands, providing a stable environment.

The first modern humans lived about 200,000 years ago in Africa south of the Zambezi River, researchers reported today (October 28) in Nature. This is the information stored in the mitochondria, the structure that generates energy for cells. Unlike nuclear DNA, which is passed on by both mother and father, mitochondrial DNA is passed on only by the mother, which means it is not jumbled up in each generation.

This research pushes back the estimated emergence of L0 to 200,000 years, which is in line with a broader trend in human origins science that is pushing back the timing of the emergence of modern humans, once thought to have been as recent as 100,000 years or fewer.

Today, the L0 lineage is known to be most common in sub-Saharan African populations, and is much rarer in the rest of the world.

In the study, Professor Hayes and her colleagues collected blood samples to establish a comprehensive catalogue of modern human's earliest mitogenomes from the so-called "L0" lineage. "What has been long debated is the exact location of this emergence and subsequent dispersal of our earliest ancestors", says study lead Professor Vanessa Hayes from the University of Sydney and Garvan Institute of Medical Research; the South African by birth is also an Extraordinary Professor at the University of Pretoria. "This allowed us to refine the evolutionary tree of our earliest ancestral branches better than ever before".

This homeland was south of the Greater Zambezi River Basin region and includes all of northern Bostwana and stretches into Namibia to the west and Zimbabwe to the east.

Nowadays this region doesn't look very inviting - it's mostly covered in desert and salt pans. Prior to the emergence of modern humans, the lake began to drain because of shifts in tectonic plates that lay beneath it.

Thus, there could have been many homelands, rather than one, which have yet to be pinned down.

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The study shows that this oasis provided a ideal home to early humans for more than 70,000 years.

What's more, our genetic data suggests the southerly migrants went on to inhabit the entire southern coast of Africa, with multiple sub-populations and huge population growth.

Combining those data with predictions about the climate and geography in southern Africa around 200,000 years ago, the authors estimate that the first modern humans lived near a massive body of water called Lake Makgadikgadi.

The first migrants are ventured north-east, followed by a second wave of migrants who traveled south-west and a third population stayed in the homeland until today.

Scientists say they've pinpointed the homeland of all humans alive today to a region south of the Zambesi River. We speculate that this created passages of lush vegetation for our ancestors to leave the homeland, most likely following the game animals that were also forging into new regions.

"Our simulations suggest that the slow wobble of Earth's axis changes summer solar radiation in the Southern Hemisphere, leading to periodic shifts in rainfall across southern Africa", says Professor Timmermann.

The climate then began to change thanks to "One" Modification of Earth Orbit " explains Axel Timmermann, oceanographer, co-author of the study, The Lake Disintegrated, The Area Gradually Dried Out and the population began to migrate over "green corridors" to the northeast and then to the southwest. After all, it's not in complete agreement with other studies.

We already know that genetic data points to southern Africa as the cradle of humanity (unlike fossil evidence, most of which has been found in East Africa).

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