GENETICS

The Deepest Branch of the Family Tree

between ~350,000 and ~260,000 years ago

Palaeolithic · Middle Stone Age · MIS 8

Genomes carry their own chronology. Sequencing the remains of a boy who lived on the South African coast two thousand years ago, before recent admixture blurred the record, let researchers estimate when the ancestors of today's Khoe-San peoples parted from the ancestors of everyone else: between 350,000 and 260,000 years ago, the deepest known split among living humans. The Khoe-San still carry the greatest genetic diversity measured in any human group.

Why it matters

The date matters less than what it rules out: a recent, single origin. Humanity was already old and structured deep in the African Middle Stone Age, around the time of the Jebel Irhoud and Florisbad fossils. Whether the signal records one clean divergence or a web of connected populations drifting apart and remixing is exactly what geneticists now argue about, and the answer will decide how our species' beginning should be told.

Dating & uncertaintyDisputed

A genetic estimate, and a live debate about what it measures. Ancient genomes from South Africa place the first divergence among modern human populations between 350,000 and 260,000 years ago. A rival analysis argues the deep signal comes instead from a weakly structured African stem: several connected populations exchanging genes for hundreds of thousands of years, with the earliest clean split among today's peoples closer to 135,000 to 120,000 years ago.

Sources

1. Schlebusch et al. (2017), Science · Southern African ancient genomes estimate modern human divergence to 350,000 to 260,000 years agodoi:10.1126/science.aao6266
2. Ragsdale et al. (2023), Nature · A weakly structured stem for human origins in Africadoi:10.1038/s41586-023-06055-y
3. Schlebusch et al. (2020), Molecular Biology and Evolution · Khoe-San genomes reveal unique variation and confirm the deepest population divergence in Homo sapiensdoi:10.1093/molbev/msaa140

Our species’ history as one day

01:08:3422 h 51 min before midnight

if the 315,000 years of Homo sapiens were compressed into a single day