900,000years ago, humanity came close to extinction
Reconstruction of a Homo sapiens among other members of the human family. Based on the cast of Mandal man's skull discovered at Mandal-li in Korea.
The study of our genome reveals that the human race almost became extinct during the first half of the Pleistocene. Our ancestors of the genus Homo would have seen their population drop by 98.7%.
A group of Chinese and Italian researchers, specializing in biostatistics and genomic studies, published a fascinating and chilling article in the scientific journal Science in August 2023. They made a major discovery about the ancestors of Man: there At 900,000 years ago, we would have come very close to extinction.
It's hard to imagine, with more than 8 billion of us evolving on Earth since last year, that there was a time when we were an endangered species. Caught in the frenzied spiral of our demographic growth and our ever more exponential consumption of earth's resources, we are today at a point where the virgin world of our activities has almost completely disappeared.
But, going back the thread of evolution, through a study of the genome of 3,154 modern individuals, researchers have shed light on an era when the ancestors of the different branches of human evolution saw nearly 98.7% of their population disappear. The main reason for this mass extinction could well be violent climate change which led to an ice age.
ANSWERS IN THE GENOME OF MODERN MAN
In order to delve into the distant past of our ancestors, scientists had to innovate. “By looking at the DNA of modern humans,” says Yi-Hsuan Pan , a specialist in molecular evolutionary biology at East China Normal University , and co-author of the study, “we can reconstruct the history of our past using various mathematical tricks. The scientists then developed a rapid coalescence process in infinitesimal time (FitCoal) which makes it possible to circumvent the difficulty of a lack of fossil archives in Africa and Eurasia over the prehistoric period from 950,000 to 650,000 before the present day, and to “retrace population histories”.
Yi-Hsuan Pan explains that the teams managed to identify what she describes as an ancient “bottleneck” based on the genomic study of fifty-two modern human populations. “We established several models to validate the existence of this bottleneck and determine that dispersal from Africa could influence its identification.” Haipeng Li , a population geneticist at the University of the Chinese Academy of Sciences in Beijing and co-author of the study, explains in a Nature article that "the discovery of this bottleneck may explain the chronological gap » from 950,000 to 650,000 BC, due to the near extinction of these species.
Nick Ashton , an archaeologist at the British Museum in London, co-authored a related study, which questions the surprisingly low number of hominid individuals believed to have survived over a long period, alongside Professor Chris Stringer , a British paleontologist. He says the geneticists in the current study studied "genetic variations in modern populations, using defined mutation rates to go back in time and estimate population size in the past."
Schematic illustration of the risk of extinction of the first hominids around 900,000 years ago.
“By analyzing data sets,” explains Yi-Hsuan Pan, “we discerned an ancient bottleneck where the population went from 100,000 to 1,280 individuals,” representing a disappearance of almost 98.7% of the total population of human ancestors. For nearly 11,700 years, our ancestors survived in small groups, probably localized, of barely a thousand individuals, in the middle of the ice age.
A LITTLE STORY OF EVOLUTION THAT COULD NEVER HAVE BEEN TOLD
Everything indicates, according to scientists, that these small groups of survivors were the ancestors of the genus Homo . “The authors of the article suggest that the population is the ancestor of Homo sapiens ”, specifies Nick Ashton, but also potentially of “Homo heildebergensis , Homo rhodesiensis , Homo antecessor or Homo bodoensis ". This discovery also aligns with many previous studies that have postulated the "origin of modern humans in Africa" situates Yi-Hsuan Pan.
The decline of our ancestors “seems to have occurred quite suddenly,” reports the biologist. Based on the results obtained, scientists envisage a first significant population decline around a million years ago, then a peak in mortality around 900,000 years ago. Nick Ashton nevertheless specifies that the archaeological evidence, largely insufficient, suggests a regional demographic collapse, while the authors of the genomic study “lean towards a global collapse”.
Hominid fossils dated from 950,000 to 650,000 BCE are indeed very rare or even impossible to find in Africa. “This period [for which there is little or no archaeological evidence] coincides with the transition from the beginning of the Middle Pleistocene, between 1,250,000 and 700,000 years BCE,” explains Yi-Hsuan Pan. Scientists associate this transitive context of slowdown, then
general demographic decline, with climatic phenomena which would explain why a large part of the population was decimated, explaining at the same time that we find so little archaeological evidence on more 10,000 years old.
Source: websites