Humanity was on the verge of extinction in the Ice Age

Our ancestors’ population may have suffered a sharp decline in the early to mid Pleistocene, with a sharp decline in the reproductive population, of which there are only approximately 1,300 individuals left, threatening humanity as we know it.

A study published today in Science, led by the Chinese Academy of Sciences, raises the theory that between 800,000 and 900,000 years ago, there was a ‘bottleneck’ at which 98.7% of the ancestral population was lost.

The proposed reasons for this population decline are mainly climatic: glacial events that caused temperature changes, a potentially prolonged period of severe drought and the loss of other species potentially used as a food source, according to a statement.

The research relies on a genomic model called FitCoal, from which they were able to accurately make demographic inferences using human genome sequences from 3,154 individuals from 10 African and 40 non-African populations.

Modeling indicates that “direct bottleneck effects were found in all 10 African populations, but only a weak signal of their presence” was detected in the rest, the authors write.

That period, which spanned about 117,000 years, coincides with the time when many researchers believe the last common ancestor of Denisovans, Neanderthals, and Homo sapiens lived.

An analytical article published in Science and prepared by scientists from the British Museum who were not involved in the study suggests that this “bottleneck” theory must be substantiated by human fossils and archaeological evidence, for which there is a chronological period gap in the fossil records of Africa and Eurasia.

The work also indicates that in this transition between the Early and Middle Pleistocene, only about 1,280 individuals remained able to maintain populations during that period, but with a loss of genetic diversity.

The team, also made up of Italian and American researchers, notes that although the study has shed light on some aspects of early-to-mid Pleistocene ancestors, there are still many questions that need to be answered.