A key period in human evolution wasn't in Africa – David Reich

David Reich argues the 2M–500K year period of human evolution may have centered in Eurasia, not Africa, challenging the standard out-of-Africa assumption.

• Genetic and archaeological evidence does not clearly place the main ancestral human lineage in Africa between 2 million and 500,000 years ago.
• Ancient DNA from Eurasia shows multiple archaic branches (Denisovans, Neanderthals, unknown lineages) with no comparable African record.
• The Africa-centric assumption is partly inertia, not direct evidence, according to Reich.
• A plausible model: modern human subpopulations extended into the Near East hundreds of thousands of years ago and interbred with Neanderthal ancestors there.
• Africa and Eurasia were not meaningfully isolated—gene flow across the two regions over tens or hundreds of thousands of years was likely routine.
• Modern human DNA within Africa is highly substructured, implying multiple archaic African lineages merged into present-day people.
• Critical missing data: ancient DNA from Africa at 50K, 100K, and 200K years ago, which could resolve how lineages braided together.

2024-09-02 · Watch on YouTube