Humans were on the brink of extinction 900,000 years ago, before the Great Migration.
Determining the time period is an important step in determining the cause of humanity’s near extinction.
Even before Homo sapiens evolved, our ancestors were on the brink of extinction. One study puts the date at 1.15 million years ago, another at 200,000 years ago. One study puts it at 1.15 million years ago, another at 200,000 years ago. A review of the data supports the latter theory and may reveal one of the most important events in the human lineage.
The genome of one species may still contain evidence of a period when the organism experienced an extreme bottleneck and declined to a few percent of its previous population. This inbreeding legacy increases the risk of extinction for many generations, but some eventually recover.
In the case of humans, the bottleneck probably occurred among ancestors long before the species Homo erectus existed, but its legacy can still be found today. However, geneticists and paleontologists disagree on when the bottleneck occurred, with some papers offering different dates. It is important to resolve this issue. Without knowing the timing, it is almost impossible to determine the cause. The new study resolves this discrepancy and proves that there was an unidentified human migration in the process.
The case that the bottleneck occurred 930,000 years ago was proven by a genetic study last year. According to that study, this was not a short-lived calamity. On the contrary, the population has remained at a delicately low level for 117,000 years, placing it in the category of endangered species by modern standards. The genetic diversity of modern humans is nearly two-thirds of what it would be without the bottleneck.
Even at the time this paper was published, the accompanying commentary questioned this finding. Archaeological evidence suggested that hominins were widespread at the time, but for some reason, the commentators argued, most of it did not contribute to modern genetics.
Even the author of that paper acknowledged that in such cases, genetics does not have all the answers, and archaeological corroboration is needed. Only a few weeks later, the same journal published independent evidence of a significant decline in human habitation between 1,154,000 and 1,123,000 years ago.
A second study attributed the disappearance of inhabited areas to the rapid increase in climate change that drove human ancestors out of Europe.
Professor Giovanni Muttoni of the University of Milan and Professor Dennis Kent of Columbia University set out to resolve this disagreement. They concluded from oxygen isotope changes that the first major Pleistocene ice age occurred about 900,000 years ago.
This is consistent with the genetic interpretation, but what about the archaeological gap? Matoni and Kent concluded that archaeological sites in Europe and the Middle East should be re-examined to reveal earlier population crashes and that dating is not as reliable as previously claimed.
There is some evidence that hominins were present in East Asia until 2.1 million years ago, but their numbers are sparse, and it is not possible to determine population movements, Matoni and Kent argue.
On the other hand, the duo argues that human settlements began to appear throughout Eurasia around 900,000 years ago. They interpret this data as indicating that the very arid conditions in Africa became so unpleasant for our ancestors during this period that most of them became extinct. On the other hand, the lower sea level made it easier for the survivors to migrate out of Africa and become the ancestors of the Neanderthals and Denisovans. Matoni and Kent argue that many other African animals, such as elephants, made similar migrations at the same time. The authors are not certain whether other hominids were indeed early inhabitants of Eurasia. If so, Matoni and Kent suggest, they may have been overtaken by the newly arrived hominids or may have gone extinct early for other reasons. In any case, Neanderthals and Denisovans did not leave behind in the human genome even the small contribution that the first sapiens made when they left Africa again 100,000 years ago.
Source: Humans were on the brink of extinction 900,000 years ago, before the Great Migration.
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