Hominin population bottleneck coincided with migration from Africa during the Early Pleistocene ice age transition

The timing and causes of hominin (pre-Homo sapiens) migrations out of Africa have been of recent interest. Two scenarios, one based on modern genomic data and the other on the chronology of hominin sites, indicate population bottlenecking in the Early Pleistocene. An ice age is invoked as bottleneck trigger in both cases even though they differ in timing, and therefore in the actual event that triggered depopulation. Our assessment of the chronology of key hominin sites in Eurasia leads us to conclude that bottlenecking occurred at the first major ice age of the Pleistocene, ~900,000 y ago, in agreement with the genomic model, and coincided with a major diaspora from Africa into Eurasia when hominins came close to extinction.