
Geographic population structure and local extinctions can explain the observed declines in Neanderthal effective population size over the last 20,000 years, without requiring an actual decline in the number of individuals.


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PSMC estimates of Neanderthal effective population size ( N  e ) exhibit a roughly 5-fold decline across the most recent 20 ky before the death of each fossil. To explain this pattern, this article develops new theory relating genetic variation to geographic population structure and local extinction. It argues that the observed pattern results from subdivision and gene flow. If two haploid genomes are sampled from the same subpopulation, their recent ancestors are likely to be geographic neighbors and therefore coalesce rapidly. By contrast, remote ancestors are likely to be far apart, and their coalescent rate is lower. Consequently, N  e  is larger in the distant past than in the recent past.

New theoretical results show that modest rates of extinction cause substantial reductions in heterozygosity, Wright’s F  ST , and N  e .

### Competing Interest Statement

The authors have declared no competing interest.

Genetic Evidence for Geographic Structure within the Neanderthal Population

neanderthal-and-denisovan-population-declines-likely-reflect-geographic-structure-not-actual-decline


Neanderthal and Denisovan Population Declines Likely Reflect Geographic Structure, Not Actual Decline
