Modern humans originated in Africa and spread to other parts of the world around 35,000 years ago, while Neanderthals evolved in Europe and western Asia. Both species used tools and fire, built shelters, and buried their dead. However, modern humans had larger brains and formed larger social groups, which helped them outcompete Neanderthals. As modern human populations increased in Europe, they interbred with and eventually replaced Neanderthals, who went extinct around 30,000 years ago.