Our Ice Age ancestors in Europe, 15,000 years ago, may have used words we would recognize today, according to a new study out this week in a US journal. Words that sound alike in related languages are generally assumed to have come from a common root, like "father" in English and "pater" in Latin. Lead author Mark Pagel, an evolutionary biologist at the University of Reading in Britain, and his team were able to take the analysis a step further by showing that certain very commonly used words, like pronouns, are more likely to stay the same over the millennia.