Eight thousand years ago small bands of seminomadic hunter-gatherers were the only human beings roaming Europe's lush, green forests. Archaeological digs in caves and elsewhere have turned up evidence of their Mesolithic technology: flint-tipped tools with which they fished, hunted deer and aurochs (a now extinct species of ox), and gathered wild plants. Many had dark hair and blue eyes, recent genetic studies suggest, and the few skeletons unearthed so far indicate that they were quite tall and muscular. Their languages remain mysterious to this day.