Scientists Find Exactly When Humans Almost Went Extinct
The early Pleistocene was not kind to our ancestors. Between 813,000 and 930,000 years ago, an alarming population bottleneck nearly caused human extinction, leaving fewer than 1,300 breeding individuals. Researchers used a computer model to uncover this staggering revelation, which was published in Science and aligns with a gap in the African and Eurasian human fossil records.
Scientists have found that almost a million years ago, humanity reached a population bottleneck with just over 1,000 people capable of breeding.
Population bottlenecks, leading to drastic reductions in species numbers, pose a serious risk to their survival, edging them towards extinction. These events diminish genetic diversity significantly. This decline can result in unhealthy populations, amplifying the threat of human extinction.
Modern bioengineers are crafting methods like cloning and gene editing to counteract the effects of population bottlenecks. These techniques help in synthesizing genetic diversity, thereby maintaining species’ health. Through these innovations, they aim to reduce the potential threat of human extinction.
Population bottlenecks, although concerning, don’t always signify the end for species. For instance, the kākāpō of New Zealand and the vaquita porpoise face more severe threats from human actions than genetic limitations. Intriguingly, an ancestral human species seems to have faced a similar population-culling threat.
The near-human extinction event is theorized to have been brought about by sudden climate change.
The significance of this human extinction risk was unearthed by researchers using a tool called the fast infinitesimal time coalescent process (FitCoal). Through their analysis of 3,154 modern genomes spanning both African and non-African populations, they identified a profound bottleneck in African populations. This bottleneck, which threatened human extinction, is believed to have been instigated by drastic climatic changes.
Archaeologist Nick Ashton and paleoanthropologist Chris Stringer shed light on this phenomenon in an article published alongside the recent research. They suggested that if a global event like severe cooling caused the bottleneck, its effects would’ve reached beyond Homo sapiens. Nevertheless, such bottlenecks bring to light the vulnerability and fragility of early human populations, emphasizing how close they came to human extinction.
The fossil record only showcases Homo sapiens emerging around 300,000 years ago. This suggests that the bottleneck, which held the threat of human extinction, primarily affected our ancestors. Among these ancestors, fossils of Homo heidelbergensis from the bottleneck period suggest a critical evolutionary turn, hinting that this event could have led to the emergence of the last common ancestor of Denisovans, Neanderthals, and modern humans.
The insights by Ashton and Stringer introduce a layer of complexity to this narrative of human extinction. There’s ongoing debate regarding the timeline of this last common ancestor. However, it’s undeniable that the bottleneck’s severity could have significantly steered the evolutionary course of early hominins, reshaping the narrative of human extinction.
Studying population bottlenecks reveals the impact of climatic changes on communities and their potential role in human extinction.
Genetic modeling, a rising field, stands as a beacon in understanding these brushes with human extinction. By comparing ancient DNA with its modern counterparts, researchers can decode the journeys and interactions of ancient human populations. This decoding offers a more comprehensive understanding of human evolution, migration, and the repeated challenges of human extinction.
Studying population bottlenecks reveals the impact of climatic changes on communities and their potential role in human extinction. By comparing ancient DNA with modern genetic samples, researchers gain profound insights. Such studies are crucial in understanding human expansion and the ever-present threat of extinction.
