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Chinese researchers have unveiled a groundbreaking study, suggesting that our human ancestors faced near-extinction around 930,000 years ago due to a climate-induced bottleneck, shedding light on our species’ precarious past.
No place on Earth has escaped the influence of Homo sapiens, but a recent study by Chinese researchers suggests that the existence of our species came perilously close to never happening at all. According to their findings, the ancestors of modern humans experienced a massive population crash approximately 930,000 years ago, brought about by a dramatic climate change event.
During this bottleneck period, the population of our human ancestors dwindled to fewer than 1,280 breeding individuals, lasting for over 100,000 years before rebounding. The researchers estimated that approximately 98.7 percent of human ancestors were lost during this bottleneck, putting the survival of our species at risk. Their findings were published in the journal Science.
The implications of this research are profound. It raises the possibility that a climate-induced bottleneck played a pivotal role in the divergence of early humans into two distinct evolutionary lineages—one eventually leading to Neanderthals and the other to modern humans.
However, some experts in the field remain skeptical of the novel statistical methods used in the study. Stephan Schiffels, a population geneticist at the Max Planck Institute for Evolutionary Anthropology, compared the study’s methodology to inferring the size of an object dropped into a lake solely from the ripples that reach the shore.
For years, scientists have pieced together the history of our species by analyzing the genetic makeup of living individuals. Recent advances in DNA sequencing technology have allowed for more sophisticated analyses, and scientists can now compare the complete genomes of people from different populations worldwide.
Haipeng Li, an evolutionary genomics researcher at the Chinese Academy of Sciences, and his team developed a method called FitCoal (Fast Infinitesimal Time Coalescent) to reconstruct evolutionary history with fine-grained precision. By comparing the genomes of over 3,000 individuals from 50 global populations, they identified the bottleneck event around 930,000 years ago.
Before the bottleneck, the researchers estimate that our ancestors numbered around 98,000 breeding individuals, which dramatically dropped to fewer than 1,280 during the bottleneck, persisting for over 117,000 years before the population began to recover.
The researchers argue that this bottleneck event aligns with the fossil record of our human ancestors, particularly in Africa, where the remains from this period are scarce. However, other experts suggest that alternative models should be explored to confirm these findings.
The Chinese researchers propose that a global climate shift caused the population crash 930,000 years ago, citing geological evidence of a colder and drier planet at that time, which may have made food sources scarcer for our ancestors. Yet, some scientists point out that remains of ancient human relatives from that era have been found outside of Africa, suggesting that the impact may have been more localized.
Additionally, the study suggests a potential link between the bottleneck event and the divergence of modern humans from Neanderthals and Denisovans, speculating that the fused set of chromosomes unique to humans may have arisen and spread within the tiny population during this time.
While the findings are intriguing, some experts like Dr. Schiffels remain cautious, emphasizing the need for further evidence and exploration of alternative explanations. The study underscores the complexity of unraveling the mysteries of our species’ ancient history.
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