Not only, some mutations remained for no apparent reason while the non-mutated remained too. Think eyes color for example. Or some other non-lethal mutations some people have.
True enough -- but it's also true that we can't claim to know what everything in our body does and why. Eye color, obviously, is not going to turn out to have some amazing significance, but a different example might. Also, I'm interested in knowing if varying eye color is strictly a mutation or not, and if so how the various colors came about. Raises some questions for me.
People with lighter eyes tend to have more sensitivity to light. Couldn't there be a biological advantage to having darker eyes?
Perhaps not the best source but then, I'm about to watch a movie and am short on time.