4 ms·

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

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)

jfager 15y ago
They're also useful for facial expressions, which clearly have reproductive implications.
sambeau 15y ago
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.
etcet 15y ago
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?

4 ms·

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

by martinkallstrom 15y ago

jfager 15y ago
They're also useful for facial expressions, which clearly have reproductive implications.
sambeau 15y ago
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.
etcet 15y ago
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?