Study: Extreme cold wiped out human ancestors 900,000 years ago

COLUMBIA: A new study suggests that human ancestors almost died out owing to extreme cold and extended droughts in Africa and Eurasia, around 930,000 and 813,000 years ago.

The research, using DNA analysis, sheds light on a critical moment in human evolution when a declining population of our ancestors managed to survive and recover, potentially giving rise to modern humans, Neanderthals, and Denisovans.

According to population geneticist Wangjie Hu and colleagues from the Icahn School of Medicine at Mount Sinai in New York City, a relatively small group of individuals emerged as survivors of this population decline. Previous DNA studies of ancient fossils suggested that this common ancestral species appeared sometime between 700,000 and 500,000 years ago.

During the challenging freeze that lasted around 117,000 years, the human genus Homo maintained an average population of about 1,280 individuals capable of reproduction. This critical number of potential breeders ensured the continuation of the lineage and prevented extinction.

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Meanwhile, before the tough climate began, the ancient population had around 58,600 to 135,000 individuals who could have children, as figured out by the researchers. They used a new way of studying shared gene traits in present-day humans from Africa and Europe/Asia to come to these findings.

The study shows that a drop in population from around 930,000 to 813,000 years ago is the most likely explanation for the genetic changes seen. It’s interesting that Africans have stronger genetic signs of this old population decrease compared to non-Africans.

Nonetheless, certain researchers think that the recovering population could have turned into the Homo heidelbergensis species, but others doubt this because of differences in the fossils’ skeletons linked to this species. Still, experts like archaeologist Nick Ashton and paleoanthropologist Chris Stringer have tentatively agreed with the study’s results.

Although the study gives us ideas about how ancient populations changed, some genetic experts are unsure and think more research is needed to consider things like interbreeding and where these people lived.

Despite the debates, study highlights the potential impact of climate shifts on human ancestors and the complex challenges they faced during a critical phase in our evolution. Hu and his team plan to improve their study by using more ancient human DNA and a wider variety of present-day genetic information.