I'm nearsighted. In the survival-of-the-fittest competition of tribe against tribe I would not have survived, being unable to hunt, or throw a spear accurately in battle.
At best I would have been the guy who stares into the fire at night, shouting, "I see visions!"
I believe this explains my lifelong sleep pattern. Up all night, vigilant and tense; relax into slumber at dawn. The nearsighted guys were the ones who got night sentry duty, guarding the mouth of the cave till the others awoke.