An 18,000-year-old human genome has been sequenced as a consequence of genetic research of ancient African skeletons, revealing information as to how the continent’s former people lived, migrated, and reproduced. Early African populations began to create large social networks some 50,000 years ago, according to researchers in the journal Nature, but became more fragmented around the time of the Last Glacial Maximum.
Although archaeological evidence suggests that ancient Africans began exchanging obsidian and other symbolic objects as early as 300,000 years ago, long-distance trade did not fully take off until the Later Stone Age. Researchers have often believed that the movement of goods coincided with the migration of people, but due to a lack of genetic data, this notion cannot be confirmed.
In general, DNA cannot survive in Africa’s hot and humid climate for lengthy periods of time, and researchers have never previously sequenced a sub-Saharan African human genome older than 9,000 years. The authors of this new study, on the other hand, retrieved genetic material from six people buried between 5,000 and 18,000 years ago in Malawi, Tanzania, and Zambia.
They also looked at the records of 28 previously reported individuals found at burial sites around the continent, and 15 of them had their genetic data upgraded. The researchers revealed that these 34 people were descended from three unique source populations originating in northeastern, central, and southern Africa after studying their DNA. This means that the continent was originally inhabited by three distinct groups who must have lived in isolation for long periods of time. The intermingling of these three lineages at every burial site, on the other hand, suggests that genetic information was exchanged between the three populations before 20,000 years ago.
According to the authors of the study, this process began around 50,000 years ago, because archaeological records suggest an increase in the movement of products over great distances around this time. People are thought to have started having offspring with partners from far-flung places as trading networks grew across the continent.
However, the genomic data shows that this long-range DNA interchange began to decline some 20,000 years ago, implying that humans began reproducing with their immediate neighbors at that time. According to the study’s authors, this timeframe corresponds to the Last Glacial Maximum, when climate change may have limited people’s mobility and pushed them to become more sedentary.
In a statement, study author Jessica Thompson noted, “At first, people recruited reproductive mates from a wide geographic and ethnic pool.” “Further down the line, people valued partners who lived closer to them and were perhaps more culturally similar.” “Perhaps it was because previously established social networks allowed for the movement of information and technologies without requiring people to migrate,” says co-author Elizabeth Sawchuk.
Importantly, the discovery of ancient DNA in Sub-Saharan Africa allows researchers to confirm certain hotly debated theories about how and when the continent’s ancient inhabitants first started traveling large distances to find companions.
Previously, archaeologists had to rely on material artifacts to speculate about possible social networks across the continent, but the addition of DNA data allowed scientists to build a more complete picture. “It’s been difficult to recreate events in our distant past using today’s DNA, and artifacts like stone tools and beads can’t tell us the complete story,” Sawchuck explained. “The missing piece of the puzzle was ancient DNA, which provides direct insight into the people themselves.”
