REGULAR meals of mammoth meat helped some early human tribes to expand more quickly than their largely vegetarian contemporaries, according to a genetic study. Human populations in east Asia about 30,000 years ago developed at dramatically different rates, following a pattern that appears to reflect the availability of mammoths and other large game. In the part of the region covering what is now northern China, Mongolia and southern Siberia, vast plains teemed with mammals such as mammoths, mastodons and woolly rhinoceroses and the number of early human beings grew between 34,000 and 20,000 years ago. Further south, where the terrain...