(Photo : Wikimedia Commons/Peemeeks)
Ancient humans were doomed millions of years ago, but they survived. The harsh climate in Africa could have reportedly extinguished them.
Ancient Humans Migrate To Avoid Climate Extinction
A recent study learned that there was a catastrophic bottleneck that nearly drove modern humanity to extinction. Our ancestors were reduced to a breeding population of only 1,300 individuals. There was also a simultaneous enormous human migration out of Africa.
The climatic upheaval that was happening about 900,000 years ago caused the population bottleneck in the ancestor of modern Homo sapiens and their migration to occur simultaneously.
"We suggest that the enhanced aridity during marine isotope stage 22 that caused the spread of savanna and arid zones across much of continental Africa pushed early Homo populations in Africa to adapt or migrate to avoid extinction," the researchers wrote.
"Rapid migration in response to a severe climate trigger and concomitant means to escape is what can account for the ... migration out-of-Africa at 0.9 million years ago and contribute to the modern genomic evidence in modern African populations of the bottleneck."
This finding supports the earlier dating of the population fall and implies that the two are related to a single event called the Mid-Pleistocene Transition, during which the Earth's climate experienced a period of extreme instability that resulted in the extinction of numerous species.
It is challenging to reconstruct the migration of early people from Africa into and across Europe and Asia. It can be difficult to date, but the greatest evidence we have is a limited record of largely stone items and bones. The evidence, however, points to several waves of early hominids and human predecessors who packed up their lives and traveled great distances into new areas rather than a single occurrence.
The chronology of the hominid sites and the genomic evidence point to the simultaneous occurrence of the bottleneck and the migration. Global ocean levels fell and huge stretches of aridity appeared in Asia and Africa during the Mid-Pleistocene Transition.
African hominids would have endured appalling conditions that deprived them of food and water. Luckily, they were able to scuttle away as land routes into Eurasia opened up due to the sea level dropping.
What Is Out of Africa Theory?
The "Out of Africa" theory is one explanation for the origin and dispersal of modern humans. The idea states that humans descended from archaic hominins living outside of Africa through intermarriage, and that humans left East Africa some 70,000 years ago.
Whether modern humans interbred with the archaic tribes they eventually replaced, such as the Neanderthals, is the key issue of contention that pits the theory against the multiregional model despite differences of opinion regarding the dates and paths of dispersals. The ancient DNA data has made this debate more intricate in the last few years. As this was going on, concepts like "leaky replacement" and "assimilation" gained popularity and eliminated the contradiction.
In the 19th century, Charles Darwin was well known for proposing that humans originated in Africa. Darwin argued that because gorillas and chimpanzees can be found all over Africa, these animals must have originated there, while contemporary people have no known origins. Huxley's studies on comparative anatomy proved that primates and contemporary humans have a similar ancestor.
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