Humans nearly went extinct 900,000 years ago, say scientists. Here's what we know

Humanity nearly went extinct around 900,000 years ago. Scientists say that the population capable of reproduction at the time declined to just around 1,300. Even more shocking, their population remained at that minuscule number for nearly 120,000 years. So, what happened? And how did humanity rebound? Let’s take a closer look: What do we know about the study? The study was published in the peer-reviewed academic journal Science on 31 August, as per CNN. The results are derived from a computer model developed by scientists in the US, China and Italy. As per France24, the study relied on genetic data from 3,154 human genomes from 50 population groups across the globe. Fabio Di Vincenzo, an anthropologist at the University of Florence and Giorgio Manzi, a palaeontologist at the Sapienza University of Rome – two of the study’s coauthors, said their computer model is named FitCoal.

Calling it ‘entirely innovative’, they claim it is 95 per cent accurate.

“We need to look at the genetic diversity present in the populations among whom the ancestors of the selected individuals lived. The lower the genetic diversity, the smaller the population,” French National Museum of Natural History senior lecturer and anthropologist Céline Bon told the website. What happened back then and why? The study said data showed that humanity suffered a population bottleneck 930,000 years ago, as per France24. The period, which lasted for 117,000 years, reduced the number of individuals that could reproduce from around 100,000 to just 1,280.

As per CNN, the study estimates that 98.7 per cent of humanity died out during that period.

Researchers aren’t sure exactly why this happened but contend that the declining numbers correlate with a gap in the fossil record. Haipeng Li, a population geneticist at the University of Chinese Academy of Sciences in Beijing, and co-author of the study, said  “the discovery of this bottleneck may explain the chronological gap”. [caption id=“attachment_13087712” align=“alignnone” width=“640”] Representational image.[/caption] Researchers also say these stark developments – which could have spelled the end of humanity – coincided with what is called the mid-Pleistocene transition. This is thought to be a time of pronounced climate change when glacial periods became lengthier and far stronger – resulting in temperatures plummeting and climatic conditions turning extremely dry. Yi-Hsuan Pan, an evolutionary and functional genomicist at East China Normal University, and the senior author of the study was quoted as saying by CNN, “The novel finding opens a new field in human evolution because it evokes many questions, such as the places where these individuals lived, how they overcame the catastrophic climate changes, and whether natural selection during the bottleneck has accelerated the evolution of human brain. “Our ancestors experienced such a severe population bottleneck for a really long time that they faced a high risk of extinction,” study co-lead author Wangjie Hu of the Icahn School of Medicine at Mount Sinai in New York City told Live Science. “These findings are just the start,” study co-author and Shanghai Institute of Nutrition and Health theoretical population geneticist and computational biologist LI Haipeng said in a statement as per Popular Science. “Future goals with this knowledge aim to paint a more complete picture of human evolution during this Early to Middle Pleistocene transition period, which will in turn continue to unravel the mystery that is early human ancestry and evolution.” ‘Provocative but…’ Nick Ashton, curator of the Paleolithic collections at the British Museum, and Chris Stringer, research leader in human evolution at the Natural History Museum in London, told CNN the study was “provocative.” They said it brought “the vulnerability of early human populations into focus.” “The estimated population size for our ancestral lineage is tiny, and certainly would have brought them near to extinction,” Stringer told Live Science.

However, they aren’t convinced that the situation was indeed calamitous.

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They pointed out that the fossil record shows that Homo Sapiens lived in and outside Africa during that period. “Whatever caused the proposed bottleneck may have been limited in its effects on human populations outside the Homo sapiens lineage or its effects were short-lived,” they told CNN. “The proposed bottleneck needs to be tested against human and archaeological evidence,” they added. Bon also pointed out to France24 that the study only counted the individuals capable of reproduction and not for example children and the elderly. French National Museum of Natural History research director and palaeontologist Antoine Balzeau told pointed out that such genetic tracing “excludes all human groups that may have lived at that time but are not our direct ancestors.” University of Wisconsin-Madison population geneticist Aaron Ragsdale told Smithsonian Magazine, “I think it’s a bit of a stretch to conclude from these results that human ancestral populations were on the verge of extinction.” With inputs from agencies