Neanderthal genes influence human head shape Research suggests the effects of long-distant interspecies breeding finds expression in modern skulls. Researchers have gleaned insights into what makes human brains bulbous from our closest evolutionary relative - the Neanderthal - despite them having died out millennia ago, according to an analysis in the journal Current Biology. Neanderthals and anatomically modern Homo sapiens coexisted in Eurasia for several thousand years before the former vanished about 40,000 years ago. But Neanderthals shared more than just their geography with our direct ancestors. They walked like us, made jewellery and bone tools like us, and they even bred with us. In fact, the faint echoes of those inter-species couplings can be seen in all modern humans with non-African heritage, in the form of splashes of Neanderthal DNA dotted throughout the H. sapien genome. They didn't exactly look like us, though. They had shorter legs and broader chests. Their heads, too