Neanderthals were archaic humans that became extinct about 40,000 years ago. They seem to have appeared in Europe and later expanded into Southwest, Central and Northern Asia. There, they left hundreds of stone tool assemblages. Almost all of those younger than 160,000 years are of the Mousterian techno-complex, which is characterised by tools made out of stone flakes. Neanderthals are considered either a distinct species, Homo neanderthalensis, or more rarely a subspecies of Homo sapiens (H. s. neanderthalensis). Modern humans and Neanderthals share 99.7% of their DNA and are hence much more closely related than to their closest non-human relative, the chimpanzee(98.8%). Compared to modern humans, Neanderthals were stockier, with shorter legs and a bigger body. The Neanderthal genome project revealed in 2010 that, through interbreeding, Neanderthals might have contributed to the DNA of modern humans, likely between 50,000 and 60,000 years ago. Today, this is apparent in the genome of most people living outside sub-Saharan Africa, as well as in some sub-Saharan Africans. Subsequent studies suggested there may have been three episodes of interbreeding. The first would have occurred soon after modern humans left Africa. The second would have occurred after the ancestral Melanesians had branched off—these people seem to have after that bred with Denisovans. The third would have involved Neanderthals and the ancestors of East Asians only. Credit: Wikipedia.