The earliest modern human colonization of Europe

The expansion of modern humans over the planet is one of the most spectacular events in the course of human evolution. During millions of years, distinctive forms of hominins evolved in parallel and sometimes coexisted in the same regions. Between 60,000 and 40,000 y ago, one species expanded out of its African birthplace and replaced all others. The Neanderthals are the best-known archaic humans to go extinct at this time. In PNAS, Lowe et al. (1) resolve pending issues surrounding the mechanism of this evolutionary drama. Their study also fuels an increasing number of questions on the antiquity of the modern human colonization of Eurasia. Scenarios accounting for the demise of the Neanderthals are much debated. For some, their replacement resulted from intrinsic biological and behavioral differences with our species (2). For others, external causes precipitated their decline at the time of modern human expansion. Of these, climatic disasters are most often envisioned (3) but a mega-volcanic eruption (4), and even an inversion of the magnetic field resulting in a brutal increase of deleterious radiation (5), have also been proposed. Epidemics devastating Neanderthal populations represent an intermediate category of explanations (6). Crucial to demonstrating any of these scenarios is the establishment of accurate chronologies for each region and their synchronization on a continental scale. For this time period, archeologists mostly use the decay of the radioactive 14C isotopes in organic matter to assess the ages of sites and human remains. Other methods are less precise or are not easily applied in archeological contexts. However, 14C isotopes virtually disappear from bones and charcoal …