Comment by saltcured

When thinking about evolutionary forces, you cannot conflate "positive" outcome with survival and reproduction. An individual might survive and produce offspring via effects that make the individual unhappy in their own life and/or with shortened life.

It's only when an effect causes death or infertility prior to normal reproductive phases that we can really say it has a direct evolutionary pressure. Anything that happens later is always going to be through secondary, social effects on how their condition supports or hinders their offspring from reproducing further generations.