Mapping Interactions of H. neanderthalensis and Homo sapiens from the Fossil and Genetic Records

Abstract

Evidence suggests that the Neanderthal and Homo sapiens lineages began diverging about 600,000 years ago, evolving largely separately in Eurasia and Africa after that time. Around 60,000 years ago H. sapiens began a significant emergence from Africa that would lead to a near-global distribution by 10,000 years ago. However, recent research on fossils from Apidima Cave (Greece) suggests that there was an earlier dispersal of our species that reached Europe more than 200,000 years ago, which is consistent with data from ancient DNA suggesting gene flow between the early H. neanderthalensis and H. sapiens lineages during the time span of the later Middle Pleistocene. Additional range expansions of H. sapiens are suggested from western Asian evidence prior to 100,000 years ago, and from China, Sumatra and Australia before the 60,000-year datum. Until recently, there were few other signs of a H. sapiens presence in Europe prior to the Aurignacian expansions that began around 41,000 years ago. However, new data from sites like Zlatý k?? (Czechia), Bacho Kiro Cave (Bulgaria), Grotta del Cavallo (Italy) and Grotte Mandrin (France) indicate that there were pre-Aurignacian dispersals that potentially placed H. sapiens populations alongside the persisting Neanderthals. While some of these populations can be related to later Eurasians, others seem to represent now-extinct lineages of H. sapiens.  It is now known from a growing body of genetic data that this co-existence of H. neanderthalensis and H. sapiens was accompanied by bouts of interbreeding between the two species. It is suggested here that a continuing absorption of Neanderthal individuals into H. sapiens groups could have been one of the factors that led to the demise of the Neanderthals.