Neanderthals lived in Europe and parts of Asia until they became extinct about 40,000 years ago. For more than a hundred years, paleontologists and anthropologists have been striving to uncover the evolutionary relationship of Neanderthals to modern humans. What does the Neanderthal genome divulge about modern humans, and how do we differ from each other? Which human capacities and characteristics hark back to Neanderthals? Why did our closest relative become extinct? One thing is now certain -- the Neanderthal and modern humans interbred -- and today we are far more closely related than we previously believed. Recently, Stanford University scientists have found that interbreeding between Neanderthals and modern humans may have given modern humans some important genetic tools needed to survive – One being the ability to combat viral infections.