Neanderthals apparently last interbred with the ancestors of today's Europeans after modern humans with advanced stone tools expanded out of Africa, researchers say. The last sex between Neanderthals and modern humans likely occurred as recently as 47,000 years ago, the researchers added.
Modern humans once shared the globe with now-departed human lineages, including the Neanderthals, our closest known extinct relatives. Neanderthals had been around for about 30,000 years when modern humans appeared in the fossil record about 200,000 years ago. Neanderthals disappeared about 30,000 year ago.
In 2010, scientists completed the first sequence of the Neanderthal genome using DNA extracted from fossils, and an examination of the genetic material suggested that modern humans' ancestors occasionally successfully interbred with Neanderthals. Recent estimates reveal that Neanderthal DNA makes up 1 percent to 4 percent of modern Eurasian genomes, perhaps endowing some people with the robust immune systems they enjoy today.
The Neanderthal genome revealed that people outside Africa share more genetic variants with Neanderthals than Africans do. One possible explanation is that modern humans mixed with Neanderthals after the modern lineage began appearing outside Africa at least 100,000 years ago. Another, more complex scenario is that an African group ancestral to both Neanderthals and certain modern human populations genetically diverged from other Africans beginning about 230,000 years ago. This group then stayed genetically distinct until it eventually left Africa.