Quote Originally Posted by no_brains_no_worries View Post
I mean, what natural selection do we really have to fear nowadays thanks to modern medicine and security? If you want to split hairs you can point out how they might be inferior to others, but all in all every living creature that is still breathing should be considered genetically fit, right?
"Survival of the fittest" got a lot of attention, but it's a bit misleading. Natural selection is blind and can only hope to react passively against changing environmental factors through mutation. Sexual selection is the real driving force behind evolution - it's an active means of strengthening one's own species.

So, no. Being genetically fit isn't about just being fit enough to survive, it's about giving one's own genes a good chance to mix with high quality genes from another member of the species. To borrow a saying of Geoffrey Miller, bodies are sinking ships to our genes. They die with us. The only way to get off the ship is to reproduce with another organism's genes. Evolution is going on all the time. You could think of genetic fitness as being somewhat relative, in that people can and do fall in love with people whose genes are not of superior quality. But there are so many different fitness indicators - kindness and intelligence, for example. Person A may find Person B to be dumb but compassionate, and they end up having fifteen babies. It wasn't the best possible genetic match, but there was still a fitness indicator being responded to. Mate choice is where it's at, evolutionarily speaking.