A new study suggests that Homo erectus, a precursor to modern humans, was using advanced toolmaking methods in East Africa 1.8 million years ago, at least 300,000 years earlier than previously thought. The study, published this week in Nature, raises new questions about where these tall and slender early humans originated and how they developed sophisticated tool-making technology. Homo erectus appeared about 2 million years ago, and ranged across Asia and Africa before hitting a possible evolutionary dead-end, about 70,000 years ago. Some researchers think Homo erectus evolved in East Africa, where many of the oldest fossils have been found,...