"About ten thousand years ago there were at least four major populations in West Eurasia — the farmers of the Fertile Crescent, the farmers of Iran, the hunter-gatherers of central and western Europe, and the hunter-gatherers of eastern Europe. All these populations differed from one another as much as Europeans differ from East Asians today. Scholars interested in trying to create ancestry-based racial classifications, had they lived ten thousand years ago, would have categorized these groups as "races," even though none of these groups survives in unmixed form today."