Ancient DNA has enabled us to answer long-standing questions about the relationship between archaic and modern humans. Admixture among archaic groups and between them and modern humans seems to have occurred whenever they came into geographic proximity. In that way, they were no different from groups of modern humans. Although most present-day human ancestry can be traced to African populations that dispersed into Eurasia ∼100,000 y ago, aDNA has allowed us to also determine which parts of our genomes are from archaic hominins that occupied Eurasia before modern humans. All non-African genomes carry small amounts of Neanderthal ancestry, and some carry an additional component of Denisovan ancestry. Because the paleoanthropological record of much of Asia is relatively poorly known, it is likely that more Neanderthal and Denisovan fossils will be found in this region. It is even possible that additional extinct groups of hominins will be identified using aDNA.
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