When and where did blue eyes appear? And why? — Peter Frost

…Why blue eyes?

We know the answers to the “when” and the “where.” Blue eyes became common during the last ice age within a region encompassing Germany, Scandinavia, the East Baltic, and probably areas farther east.

At that time, Scandinavia and the Alps were under ice. Northern Europe was habitable only on the plains stretching from northern Germany eastwards. Before 12,000 years ago, these plains were steppe-tundra with wandering herds of reindeer and nomadic bands of hunter-gatherers. Actually, they were just hunters. There were few opportunities for gathering fruits, nuts, tubers, or edible greens. Food was almost entirely “meat on the hoof” (Hoffecker, 2002, pp. 8, 178, 193-194, 237).

But why would such an environment favor blue eyes? Davide offers four possible reasons:

• Lower UV exposure requiring less melanin protection
• Sexual selection for distinctive traits
• Genetic drift in smaller northern populations
• Need for lighter skin to maintain vitamin D synthesis where sunlight is weaker

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