[hannasanarion]

Evolution doesn't do magic.

You could just as well ask, "in a world with solar UV rays, wouldn't we evolve cancer resistance?"

[im3w1l]

Arguably, we did. Our scalp is protected by hair, our flesh is covered by a skin, and the skin can tan. Then there are dna repair mechanisms, and apoptosis as the final line of defence.

Cancer mainly takes the old, and is certainly no threat to the survival of mankind.

[throwawayfeaxcz]

We have evolved UV ray resistance, it's called being black.