The sample site in Satsurblia cave. (Anna Belfer-Cohen) A cup of mud that has been buried beneath the floor of a cave for millennia has just yielded up the genome of an ancient human. Analysis reveals traces of a woman who lived 25,000 years ago, before the last Ice Age; and, although we don't know much about her, she represents a significant scientific achievement: the feasibility of identifying ancient human populations even when there are no bones to recover. The sample also yielded DNA from wolf and bison species, which an international team of scientists were able to place in...