A recent study has revealed that our human ancestors faced a severe extinction crisis approximately 930,000 years ago, with a population of only about 1,280 individuals.
Today’s global human population has exceeded 8 billion, and the issue of overpopulation poses numerous challenges. In stark contrast to our current difficulties, our ancestors confronted a completely opposite problem: the brink of extinction.
In a study published in the scientific journal Science on August 31, an international team of scientists employed new technology to analyze genetic data, discovering that our human ancestors experienced a significant population bottleneck around 930,000 years ago, with a population of just about 1,280 individuals.
This was a continuous process that reduced our ancestors’ birth rates from around 100,000 to below 1,300 over a span of 120,000 years.
The research team stated: The sharp population decline nearly marked the end of human history.
This analysis exposed the diversity of our ancestors during each period and indicated a frightening “bottleneck” nearly 1 million years ago. (Photo: Livescience)
In fact, the hypothesis that human ancestors were on the brink of extinction during the Pleistocene epoch has long been proposed, but there was no supporting evidence such as human fossils or archaeological data, rendering this hypothesis quite unconvincing.
However, at this point, new analytical methods have made it possible to estimate the timing of the emergence of current genetic variants, allowing scientists to estimate the population size of humanity during the mid-Pleistocene. The two leading scientists of the research team—anthropologist Fabio Di Vincenzo from the University of Florence and paleontologist Giorgio Manzi from Sapienza University in Rome—stated that this analytical method, known as FitCoal, can achieve an accuracy of up to 95%.
The core formula of the new inference method. The image depicts a rock painting, illustrating the ancestral human population overcoming unprecedented dangers in the shadows during a severe ancient bottleneck. (Photo: Scitechdaily)
So how does this technology work? Scientists analyzed the genomes of 3,154 individuals from about 50 populations worldwide, then used FitCoal to trace the origins of those genes to estimate the size of previous populations with similar genetic structures.
By studying the genetic diversity of the ancestors of these 3,154 individuals, the research team found that lower genetic diversity correlated with a smaller ancestral population. By tracing and comparing human gene mutations in this manner, scientists estimated that 900,000 years ago, the ancestors of modern humanity numbered only 1,280 individuals, which is the minimum viable reproductive population needed to produce all observed genetic variations in future generations.
However, the estimated figure of 1,280 individuals does not represent the entire ancestral human population on Earth at that time but rather those individuals capable of reproduction, excluding children, the elderly, or those unable to reproduce for various reasons. In other words, our ancestors at that time likely did not consist solely of these 1,280 individuals, but the actual number was probably not much higher.
The fossil distances of African hominins and the estimated timeframe of chromosomal synthesis responses are displayed on the right. (Photo: Scitechdaily).
Additionally, “this gene tracing method excludes all groups that may have lived at that time but were not our direct ancestors,” stated paleontologist Antoine Balzeau, research director at the National Museum of Natural History in France.
Simultaneously, the study found that climate change was one of the primary factors leading to the severe population decline of our ancestors.
Starting around 900,000 years ago, the Earth’s climate underwent significant changes, characterized by severe cold and drought in Africa, leading to the emergence of arid regions and isolated populations, making survival increasingly difficult. The research team believes that such uncertain environmental conditions forced our human ancestors to experience a population crisis, resulting in only 1,280 individuals remaining in the viable reproductive population.
This “population bottleneck” period lasted from 930,000 to 813,000 years ago, starting with a mysterious catastrophe that caused humanity to lose up to 98.7% of its reproductive population, leaving only about 1,280 individuals scattered across the planet. (Photo: CNN).
However, some other scientists remain skeptical of these research findings. Balzo, an anthropologist at the British Museum, stated: “The harsh climate reality is undeniable, but there is no clear evidence proving that the decline in human population has a direct causal relationship with the climate.”
Thierry Grange, a molecular geneticist at the Jacques Monod Institute in Paris, who specializes in ancient populations, expressed skepticism about the entire study, arguing that the accuracy of this timeframe is highly questionable as it cannot be determined from 900,000 years ago.
Overall, although this study has been published, it cannot be fully trusted, especially considering the improbability of such a small number of individuals maintaining the existence of an entire species.
In reality, many studies encounter similar issues, which is why these findings can only be referred to as “hypotheses.”
