Despite seeming like a relatively stable place, the Earth's surface has changed dramatically over the past 4.6 billion years. Mountains have been built and eroded, continents and oceans have moved ...

Add Yahoo as a preferred source to see more of our stories on Google. Researchers Carrie Mongle and Meave Leakey discuss Paranthropus boisei hand fossils, held in the cases pictured, at the Turkana ...