> If this mutation gives a health or fitness advantage it would be selected for. That’s not always how evolution works, especially when you’re talking about ch

> If this mutation gives a health or fitness advantage it would be selected for. That’s not always how evolution works, especially when you’re talking about characteristics that (as the writer pointed out) were not present or used during evolutionary selection. Adaptations that are selected for can and frequently do have byproduct effects that are not selected for. There are words for these effects, like “vestigial”, “tag-along”, “spandrel”, “byproduct”, “non-adaptive trait”, etc., etc.