One of humankind's most ancient genetic lineages has been successfully uncovered, after scientists sequenced the genes of the Southern African Khoisan tribespeople. This is the very first time that the genetic history of our species has been matched to the Earth's climatic conditions, Science Daily reported.
A research team led by Professor Stephan Christoph Schuster, a geneticist from Nanyang Technological University, sequenced the genome of five living people from a tribe in Southern Africa. The hunter/gatherer people of the tribe are known as the Khoisan tribespeople, and they are "genetically distinct" from Europeans, Asians, and all other Africans, according to the research paper published Thursday in Nature Communications.
The research team used advanced computer analysis of the Khoisan tribespeople and "420,000 genetic variants across 1,462 genomes from 48 ethnic groups," Science Daily explained. Remarkably, there are some individuals in the Khoisan tribe whose ancestors never bred with any other ethnic groups for the last 150 thousand years. The researchers claim that until around 20,000 years ago, this ancient lineage made up the majority of all human beings.
"The Khoisan people from Southern Africa maintained ancient lifestyles as hunter-gatherers or pastoralists up to modern times, though little else is known about their early history," the study explains. "Coalescent analysis shows that the Khoisan and their ancestors have been the largest populations since their split with the non-Khoisan population ~100–150 kyr ago. In contrast, the ancestors of the non-Khoisan groups, including Bantu-speakers and non-Africans, experienced population declines after the split and lost more than half of their genetic diversity. Paleoclimate records indicate that the precipitation in southern Africa increased ~80–100 kyr ago while west-central Africa became drier. We hypothesize that these climate differences might be related to the divergent-ancient histories among human populations."
Interestingly, the findings are in line with the ancient tribe's belief.
"Khoisan hunter/gatherers in Southern Africa have always perceived themselves as the oldest people," Schuster said, and it appears that they might have been correct. "Our study proves that they truly belong to one of mankind's most ancient lineages, and these high quality genome sequences obtained from the tribesmen will help us better understand human population history, especially the understudied branch of mankind such as the Khoisan. The new data gathered will also enable scientists to better understand how the human genome has evolved and hopefully lead to more effective treatment options for certain genetic diseases and illnesses."
Dr. Hie Lim Kim, first author of the paper, explained that "it was very surprising that this group apparently did not intermarry with non-Khoisan neighbours for thousands of years."
All of modern humanity's ethnic groups share some ancestors with the Khoisan genetic makeup, the researchers believe. The research team plan to seek out other non-admixed individuals around the world. They plan to examine the genomes of isolated tribes in South Asia and South America in the hopes of finding other ancient genetic human lineages.
[Photo via Nanyang Technological University]