The Impact of Climate Change on Early Human Ancestors: A Population Bottleneck and Speciation
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The Fate of Mankind: A Threatening Climate Change Event in Human History
About 900,000 years ago, the existence of mankind faced a grave danger when the population of our first ancestors plummeted to only around 1,000 individuals on Earth.
The Impact of Climate Change
Scientists from the Chinese Academy of Sciences believe that this decline in human ancestors can be attributed to significant climate change during that time period. This included glacial events causing drastic temperature fluctuations, severe droughts, and the extinction of several other species, which may have limited the availability of food sources.
Exploring the Fossil Record
In an effort to better understand the gap in the African and Eurasian fossil record, archaeologists conducted a study published in the journal Science. They analyzed the genome sequences of 3,154 modern humans.
A Population Bottleneck
The analysis revealed that early human ancestors went through a prolonged and challenging phase known as a population bottleneck, in which only about 1,280 individuals managed to survive and maintain a population for approximately 117,000 years. This bottleneck led to a significant loss of genetic diversity among the ancestors of ancient humans, with an estimated 65% of genetic diversity disappearing during this period.
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Speciation and Chromosome Convergence
However, scientists suspect that this population bottleneck may have played a role in speciation. They believe that two ancestral chromosomes may have merged to form what is now known as chromosome 2 in modern humans. This could have given rise to a species that was likely the last common ancestor of Denisovans, Neanderthals, and modern humans.
Unanswered Questions and Future Research
While this study has provided some unexpected findings, it has also raised further questions. The researchers hope to continue excavating to uncover how this small population managed to survive in challenging and dangerous conditions. They also emphasize the need to test the bottleneck theory against archaeological and fossil evidence.
The Path to Accelerated Evolution
Scientists suspect that firefighting, along with climate changes that made the environment more favorable for human life, may have contributed to a later period of rapid population growth around 813,000 years ago. This new knowledge opens up a new area in human evolution and raises questions about the location of these early humans, their strategies for overcoming catastrophic climate change, and whether natural selection during bottlenecks accelerated the evolution of the human brain.
Unraveling the Mystery
These discoveries are just the beginning. The goal is to paint a more complete picture of human evolution during the transition from the early Pleistocene to the Middle Pleistocene, ultimately unraveling the origin and evolution of early humans.
Source: Independent
