Modern Humans Have Their Homeland In Botswana – New Study

Conny Waters - AncientPages.com - The earliest ancestors of anatomically modern humans (Homo sapiens sapiens) emerged in a southern African ‘homeland’ and thrived there for 70 thousand years, according to a study.

Changes in Africa’s climate triggered the first human explorations, which initiated the development of humans’ genetic, ethnic and cultural diversity.

Typical region in the Okavango Delta, with free canals and lakes, swamps, and islands. source: 

“It has been clear for some time that anatomically modern humans appeared in Africa roughly 200 thousand years ago,” geneticist Vanessa Hayes of the Garvan Institute of Medical Research and the University of Sydney, who led the study, said in a press release.

“Mitochondrial DNA acts like a time capsule of our ancestral mothers, accumulating changes slowly over generations. Comparing the complete DNA code, or mitogenome, from different individuals, provides information on how closely they are related.”

Researchers collected blood samples to establish a comprehensive catalog of modern human’s earliest mitogenomes from the so-called ‘L0’ lineage.

“We merged 198 new, rare mitogenomes to the current database of modern human’s earliest known population, the L0 lineage. This allowed us to refine the evolutionary tree of our earliest ancestral branches better than ever before,” says first author Dr Eva Chan from the Garvan Institute of Medical Research, who led the phylogenetic analyses.

The study revealed that 200 thousand years ago, the first Homo sapiens maternal lineage emerged in a ‘homeland’ south of the Greater Zambezi River Basin region, which includes the entire expanse of northern Botswana into Namibia to the west and Zimbabwe to the east. The homeland region once held Africa’s largest ever lake system, Lake Makgadikgadi.

The ancient wetland ecosystem provided a stable ecological environment for modern humans’ first ancestors to thrive for 70 thousand years.

“We observed significant genetic divergence in the modern humans’ earliest maternal sub-lineages, that indicates our ancestors migrated out of the homeland between 130 and 110 thousand years ago,” explains Professor Hayes, adding that the first migrants ventured northeast, followed by a second wave of migrants who traveled southwest. A third population remained in the homeland until today.

“In contrast to the northeasterly migrants, the southwesterly explorers appear to flourish, experiencing steady population growth,” says Professor Hayes.

Researchers analyzed climate computer model simulations and geological data, which capture Southern Africa’s climate history of the past 250 thousand years.

“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,” said Professor Axel Timmermann, Director of the IBS Center for Climate Physics at Pusan National University,

“These shifts in climate would have opened green, vegetated corridors, first 130 thousand years ago to the northeast, and then around 110 thousand years ago to the southwest, allowing our earliest ancestors to migrate away from the homeland for the first time.”

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Written by Conny Waters - AncientPages.com Staff Writer