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Comment by Achshar | Hacker News Reader

Has any study been conducted about any possible side effects any such thing would have? after all if light to skull would have been so useful then evolution should have made it so. If it isn't so then either its of not much use or it has some bad effects too.

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You misunderstand evolution. The idea is to be good enough to reproduce, not to be optimal. Hence why humans have loads of vestigial crap that serves no purpose.

But we also have stuff that serves a purpose but without which we would still be good enough to reproduce. Eyebrows for example, are a good shield for your eyes against snow and dust falling from above. I'm happy to have them. But I can't imagine survival ever depending on them. Or is their existence proof that humans at some point in evolution got a real advantage from eyebrows in regards to reproduction? (serious question, I'm not being sarcastic)

They're also useful for facial expressions, which clearly have reproductive implications.

The eyebrow may have been of use when humans had predators who attacked in the rain, or it may have been advantageous to a distant ancestor who lived through a one-off natural disaster: a meteor strike or a volcano. It may also be an effective way to communicate silently when your hands are busy elsewhere, or a vital addition to those who use fire.

The eyebrow might also have never been of any competitive advantage without also being a hindrance in any way.

Evolution is all about the death of children. If a mutation leads to the death of its carrier before they can reproduce then it will be naturally selected out of the gene pool. Anything that isn't removed in this way will still remain.

In a smaller way if a mutation helps a parent (or other relation) to raise more children to adulthood then more copies of the mutation will appear in the gene pool.

All mutations start out without a use. Maybe the advantage that an eyebrow brings has yet to be realised.

Try this: shave your eyebrows and then run 5 miles. Ok by now you should have a significant amount of sweat pouring directly into your eyes, does it hurt? are they swollen? can you see well enough to throw a spear at a reindeer?

Apart from reproduction it also applies to survival. And feeling good is clearly on the side of supporting survival. Take tails for example, it does not provide any reproductive support (i believe) and it was unnecessary since we started walking on ground instead of trees so it eventually went away. Same for gills. All i am saying is that if it had good enough use, it would have made some development in the regard however small or trivial it may be.

Also my first question was regarding its side effects, evolution is just something i used to support my question, but my question in general still remains unanswered..

> Apart from reproduction it also applies to survival

Still irrelevant, evolution isn't an intelligent concept that looks at every option and picks out the best solutions. What's more, evolution isn't something that happened in the past, it's still happening; we are not the best possible animal, we are probably not the best possible human.

That's not how evolution works. Are you saying humans are currently optimal in every possible way?

No i am not saying that evolution leads to optimal development, but just that if it has such good implications then something should have happened in this regard, however small or trivial.

Evolution does not optimal development this is a general misunderstanding. Evolution is not 'survival of the fittest' it it 'survival of the just fit enough'.

Darwin was clear about this, sadly the eugenics movement of the late Victorian age were not.

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