(CNN)Early modern humans and Neanderthals lived in Europe and parts of Asia at the same time -- overlapping for several thousands of years before our archaic relatives disappeared around 40,000 years ago.
Prehistoric teeth hint at Stone Age sex with Neanderthals
During this time, Homo sapiens and Neanderthals encountered each other and sometimes had sex and gave birth to children. The evidence is buried within our genes, DNA analysis has shown, with most Europeans having around 2% Neanderthal DNA in their genomes from this ancient interbreeding.
However, there has been relatively little direct physical evidence of these encounters and fossilized bones. Skeletons that have been found haven't offered definitive proof.