Comment by hinkley

Survival of the fittest is also a wrong way to think about evolution that leads many people to make assumptions that are backward.

Selection doesn’t pick winners, it picks losers. But bad luck also picks losers, and good luck pick winners, so things with small negative or positive effects can be swamped, and anything neutral has no pressure to be phased out at all. So if being born with blue hair turns out not to have any effect on your survival, because for instance none of your predators can see blue any better than they can see what every color your mate is, then there will continue to be blue babies at some rate. And if you or your mate have other genes that do boost your survivability, then there will be a lot of blue babies. But not on the merits of being blue. However the animals involved may just decide to involve blueness in their mate selection criteria. Because correlation.

Then many generations later, if your habitat changes, or your range expands, maybe blue fur protects more or less well against UV light, or moss growing in your fur, or some new predator. Now the selection works more like people think it works. But it’s been sitting there as genetic noise for perhaps centuries or eons, waiting for a complementary gene or environmental change to create a forcing function.