Climate risk looms over humanity, a threat so profound that experts say the same factor that once nudged our species toward near extinction continues to shape our future. A research team spanning China, Italy, and the United States unveiled fresh insights from African and Eurasian fossil records through a novel method called FitCoal. Thanks to a rapid assembly process that works with surprisingly small data sets, scientists inferred demographic patterns from the genomic sequences of 3,154 individuals.
Their conclusions reveal that early human ancestors endured a long and severe bottleneck, with around 1,280 breeding individuals maintaining a population for roughly 117,000 years. Although the study sheds light on certain aspects of ancestry, many questions remain about the Early to Mid-Pleistocene era as new evidence continues to emerge.
genetic analysis
In the report published in a leading scientific journal, a large number of genomic sequences were examined. the lead scientist noted, “The capability of FitCoal to detect the ancient bottleneck with only a few sequences marks a major breakthrough.”
Analyses using this advanced approach show that early human ancestors faced an extreme loss of life and, as a result, reduced genetic diversity. The gap observed in the fossil record across Africa and Eurasia aligns with the proposed bottleneck during the Early Stone Age, suggesting a time frame when fossil evidence is notably sparse.
” The observed fossil shortfall is explained by this bottleneck, according to an anthropologist from a renowned European university.
adverse weather conditions
Possible drivers of the population decline include climate shifts. Glaciations of this era altered temperatures, triggered severe droughts, and may have disrupted food sources relied upon by ancestral humans.
It is estimated that a substantial portion of existing genetic diversity was lost during the early and middle Pleistocene as the population remained small for a long period. This bottleneck may have played a role in the emergence of a key genetic event: the fusion of two ancestral chromosomes forming chromosome 2 in modern humans. The last common ancestor of Denisovans, Neanderthals, and Homo sapiens may thus be traced to this era.
“The new method opens a path to discoveries in human evolution by asking questions about where these individuals lived, how they withstood drastic climate changes, and whether natural selection accelerated brain development during the downturn,” an East Asian collaborator remarked. The team members also stressed the importance of continuing work in this area.
There is now reason to believe that events from 930,000 to 813,000 years ago warrant deeper investigation to understand how such a small population endured under harsh and dangerous conditions. As climate shifted toward conditions more suitable for human habitation, a gradual population growth may have followed around 813,000 years ago.
“These findings mark just the beginning. Future goals include filling in the gaps to produce a more complete picture of human evolution during the transition from the Early to the Middle Pleistocene, which will keep unraveling the story of ancestry and evolution,” a population geneticist noted. Researchers from leading institutions contributed to this work, highlighting the collaborative nature of modern evolutionary science.
Reference work: a reported study in a major science publication.
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