New research has put the theory that modern humans originated from a single location in Africa to the test.
A study indicates that the Khoe and San peoples of the sub-Sahara are the descendants of the earliest diversification event in human history, dating back around 100,000 years.
According to the journal Science, the findings involved 220 participants representing 11 different populations across southern Africa, revealing approximately 2.3 million DNA variants per individual.
This genetic diversity was believed to stem from interbreeding and genetic stratification, which involves non-random mating between groups.
A team of international scientists from Sweden and South Africa carried out the largest genomic study conducted among the click-speaking Khoe and San populations.
Researchers project that the San populations from northern Namibia and Angola diverged from the Khoe and San populations residing in South Africa as early as 25,000 to 40,000 years ago.
Dr. Carina Schlebusch from Witwatersrand University in Johannesburg remarked to Science: ‘The ethnic diversity present among the Khoe-San group is astonishing.
We were able to observe many facets of the rich history that contributed to this genetic diversity.’
Many scientists hold the view that modern humans first emerged from a single African region before dispersing into Europe and Asia approximately 60,000 years ago.
Conversely, some theorize that there were multiple ‘movements’ out of Africa.
‘Modern humans may have developed from a non-homogeneous group,’ suggested Mattias Jakobsson from Uppsala University in Sweden, one of the study’s authors.
The genetic evidence also highlighted how generations of Khoe-San populations adapted to their environment, affecting aspects such as muscle function, immune response, and UV-light protection.
Farming practices evolved and propagated across southern Africa with genetic exchanges between a southern San group and populations in East Africa.
The Science journal reported that researchers concentrated on genomic signals of ancient adaptations that predated the historical separation of the Khoe-San lineage from other human groups.
Co-author Pontus Skoglund from Uppsala noted: ‘Although all current humans possess similar gene variants, the early divergence of Khoe-San from other human populations enabled us to focus on genes that have rapidly evolved in the ancestors of all those living on the planet today.’
The study will be made available for free to facilitate future research related to diseases.
by David Livingstone
