Observation and dating. A human femur from western Siberia was directly radiocarbon dated to roughly 45 ka and sequenced at high coverage. The researchers identified Neanderthal-derived genomic segments that were longer on average than in many living people. From their lengths, they estimated gene flow into ancestors of this individual roughly 7,000–13,000 years before he lived. Fu et al., Nature (2014).
Claim status. observed: a human bone, its radiocarbon results, and sequenced genome. inferred, strong: Neanderthal admixture in this person's ancestry. model-dependent: the interval between admixture and his life, which depends on assumptions about generations and recombination; later models can refine it. open: where particular encounters took place and what cultural practices either population shared. Next test: compare independent ancient genomes and model assumptions. Genetic mixing establishes contact between populations, not a shared mythology or inherited memory of a specific event.