A startling discovery in the history of human evolution has recently been made by a Chinese study.
According to the study explained in detail by Science, our ancestors were on the verge of extinction a million years ago, with a population of only 1,300 people.
The Bottleneck Mystery
Imagine a world where modern humans are almost extinct. Their numbers dwindled to a mere fraction of their current 8-billion-strong population.
This is what precisely the study, led by evolutionary and functional genomics scientist Pan Yi-hsuan and her team in Shanghai, has revealed.
Using a novel statistical model called FitCoal, the South China Morning Post reports that Pan and her colleagues unearthed a jaw-dropping bottleneck event between 930,000 and 813,000 years ago.
This bottleneck, a prolonged and severe crisis in population numbers, saw a catastrophic 99% reduction in the breeding population of human ancestors.
At its lowest point, only approximately 1,300 individuals of reproductive age were left on Earth. But what drove our ancestors to the edge of extinction?
Unraveling the Causes
While the exact reasons remain a subject of debate, the study suggests several factors may have played a role.
Long periods of glaciation, cooling sea surface temperatures, and droughts are some of the potential culprits.
These harsh environmental conditions could have made hunting for food increasingly difficult, pushing the human population to the brink.
A Timeline Rewritten
This revelation challenges our previous knowledge, primarily focused on the last 100,000 years of human history, particularly the great migration out of Africa.
The bottleneck event uncovered by the Chinese researchers happened hundreds of thousands of years before this migration, extending our understanding of population history significantly.
According to Dr. Jin Xin, deputy director at China's BGI Research Institute, "The size of populations is a crucial parameter for our understanding of human evolution. It directly impacts the diversity of the human genetic heritage and the history of evolutionary migrations. This body of knowledge forms the foundation for studying various complex diseases."
FitCoal: A Revolutionary Tool
The groundbreaking findings were made possible by the development of FitCoal, a cutting-edge statistical method.
FitCoal, short for "Fast Infinitesimal Time Coalescent," allowed the researchers to make demographic inferences using contemporary human genomic sequences more accurately and efficiently.
In a world where each human genome contains over 3 billion genetic bases, deciphering the intricate tapestry of our evolutionary history is a monumental task.
However, modern DNA sequencing technology has significantly expedited this process. The Chinese study compared the genomes of about 3,000 people from 50 populations worldwide, leveraging data from the Thousand Genomes Project and the Human Genome Diversity Project.
Expert Opinions and Skepticism
While this study has captivated the scientific community, some experts urge caution. Janet Kelso, a computational biologist at the Max Planck Institute for Evolutionary Anthropology, is skeptical, noting that the genetic signal for the bottleneck is strongest in present-day African populations and less pronounced in those outside Africa.
Nicholas Ashton, a paleolithic archaeologist at the British Museum, also expresses skepticism, highlighting the need for further exploration and evidence.
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