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comment by user-inactivated
user-inactivated  ·  3820 days ago  ·  link  ·    ·  parent  ·  post: What is the evolutionary reason for male facial hair, while women don't have it?

Does everything exhibited phenotypically have an evolutionary basis?





theadvancedapes  ·  3820 days ago  ·  link  ·  

Well - this question is kind of redundant since - yes - everything has evolved! But I take it the meaning of this question is - does everything exhibited phenotypically have an adaptive basis. And the answer to that is almost certainly not. Things can be selected for because they come in packages randomly with other genes that are functional. If the selection pressure over time is strong enough for another trait - this trait gets carried along with it - even though it wasn't advantageous one way or the other. Also, mutations can of course occur and be phenotypically expressed. These mutations are not necessarily always advantageous either - but if they are a major deterrent to increased fitness they will usually be "weeded out" - given enough time.

Phenotypic traits can also be exaptive - meaning that they evolved for a specific purpose - but now they serve a different purpose than the one they originally evolved for. A good example for this would be nails - which wouldn't have existed if we didn't evolve from ancestors who originally had claws. We didn't need claws so the exaptive relic is a hard keratin surface where claws used to be!

user-inactivated  ·  3819 days ago  ·  link  ·  

Adaptive basis is indeed what I was thinking. Thank you.

user-inactivated  ·  3820 days ago  ·  link  ·  

If I understand the question you are asking correctly, the answer is no if you buy this theory. I'm an armchair enthusiast for this sort of thing, still waiting on theadvancedapes for real answers. :p