Around 900,000 years ago, ancient humanity flirted dangerously close with extinction, dwindling to an alarmingly tiny community of approximately 1,280 reproducing individuals. Following this dramatic decrease, the early human ancestral population maintained this minimal size for nearly 117,000 years, as revealed in a novel study recently published.
This cutting-edge research, the product of an international collaboration between scientists stationed in China, Italy, and the United States, is entrenched deeply within the use of an innovative computer model. The keystone to their entire process involved analyzing genetic information of 3,154 individuals from contemporary human genomes.
The catastrophic result of this study revealed that approximately 98.7% of human predecessors had been irrevocably lost in the vast trajectory of time. Intriguingly, the researchers suggest this drastic population crash aligns with a void in the fossil record. This gap could possibly signify the emergence of a fresh hominin species, sparking the genesis of Homo sapiens and Neanderthals as we understand them today.
This groundbreaking discovery paves the path for a slew of new investigations concerned with our primeval past, focusing on the habitats of these ancestors, the harsh climate changes they endured, and whether natural selection was amplified during this bottleneck, causing a swift evolution of the human brain.
This drastic population bottleneck was likely catalyzed by the intense shift of climate during the mid-Pleistocene transition. As glacial periods intensified and lengthened, temperatures dropped and ecosystems became increasingly arid.
The scientists also proposed that human control of fire, and a gradual shift to a more accommodating climate, perhaps sparked a swift repopulation approximately 813,000 years ago. Drawing from archaeological findings, the team cited the earliest evidence of food preparation through fire tracing back 780,000 years ago in present-day Israel.
Modern understanding of ancestral populations, rejuvenated by the study of ancient DNA, has been limited as the oldest known DNA from a human species only dates back around 400,000 years. However, the computer model employed in this study uses the abundant genetic information from present day humans to infer estimates of past population sizes.
This groundbreaking research has been termed “provocative”. It draws attention to the vulnerability of early human populations. While the fossil record is sparse, it indicates the presence of early human forms in and outside Africa around 813,000 to 930,000 years ago.
Despite this proposed population collapse, fossils unearthed in areas such as China, Kenya, Ethiopia, Italy, Spain, and the United Kingdom demonstrate the survival of early human species during this period. The implications of the proposed bottleneck, therefore, may have been restricted to the Homo sapiens lineage, or could represent a brief crisis. Further probing and corroboration with human and archaeological evidence is paramount, according to commentary on the study.
