Approximately one million years ago, a catastrophic event nearly wiped out our ancestors.
Genomic data from 3,154 modern humans suggests that the population declined from about 100,000 to just 1,280 breeding individuals about 900,000 years ago. This was a staggering 98.7 percent population decline that lasted for 117,000 years and could have led to human extinction.
The fact that we are here today, and that so many people are here, is evidence that this was not the case. But a team led by geneticist Haipen Li of the Chinese Academy of Sciences and Yixuan Pan of East China Normal University says the results explain a strange gap in the fossil record of Pleistocene humans.
“The gap in the African and Eurasian fossil records can be explained by this chronological Early Stone Age bottleneck.” Anthropologist Giorgio Manzi says: from Sapienza University, Rome, Italy. “This coincides with the period when fossil evidence is thought to be significantly lost.”
population bottleneck, a significant decrease in the number of groups is not uncommon, as is known. When a species is wiped out by events such as war, famine, or the climate crisis, the resulting decline in genetic diversity can be traced through its surviving descendants. Thus, we can see that a human population bottleneck existed in the Northern Hemisphere even more recently, around 7,000 years ago.
However, the further back we look into the past, the harder it becomes to find meaningful signals.
For this latest analysis, the research team used a new method called the Fast Infinitesimal Time Coalescence Process (FitCoal) to avoid the accumulation of numerical errors typically associated with trying to unravel these past events. Developed.
They used FitCoal to analyze genomic data from 3,154 people around the world, 10 Africans and 40 non-Africans, to see how their genetic lineages diverged over time. Their results showed that there was a significant population bottleneck between about 930,000 and 813,000 years ago, resulting in a loss of up to 65.85 percent of current genetic diversity.
As for the cause of the bottleneck, we can’t be 100% sure what all the factors were, but one major event that was going on at the time may have had an impact. Mid-Pleistocene transition periodduring which the Earth’s ice ages changed dramatically.
Climate change may have created unfavorable conditions for humans struggling for survival at the time, resulting in famine, conflict, and further population decline.
“This novel discovery opens up a new field in human evolution as it raises many questions.” bread says“Where these people lived, how they overcame catastrophic climate change, whether natural selection during bottlenecks accelerated the evolution of the human brain, and more.”
This bottleneck appears to contribute to another interesting feature of the human genome: that it is formed by the fusion of two chromosomes. chromosome 2.
Humans have 23 pairs of chromosomes.everything else hominid There are 24 great apes living today. The formation of the second chromosome is speciation event It encouraged humanity to take a different evolutionary path.
“These discoveries are just the beginning.” Lee says.. “Future goals, leveraging this knowledge, aim to paint a more complete picture of human evolution during this early to mid-Pleistocene transition, and thereby Mysteries will continue to be unraveled.”
This study science.