A Climate-Driven Human Genetic Bottleneck in Africa 900 Thousand-Years Ago

Mid-Pleistocene transition (MPT), a climate state underwent low temperature and dry condition, has been suggested as a candidate for a massive genomic bottleneck in African hominins ~0.9 million years ago (Ma). However, no sufficient evidence supports such attribution to climate deterioration for the human genetic bottleneck. Here, we use an agent-based model forced by realistic time-evolving climate conditions to investigate the population and genetic changes of African hominins. With our climate-driven model simulations, population collapses are found before and during the MPT due to reductions of atmospheric CO₂ concentrations. The corresponding climate changes and vegetation loss enhance the difficulty of habitation for African hominins in northern and southern Africa. The regional extinctions create population refugia in eastern and southern Africa serving as possible genetic pools for the emergence of Homo sapiens. Furthermore, culture evolution may reinforce the expansion and dispersal of African hominins during the climate recoveries after MPT and to enhance the chance of admixture of African genetic information.