Saturday, January 23, 2010

Why do we have finger/toe nails?

What purpose do/did they serve?Why do we have finger/toe nails?
If you consider us to be the products of evolution, then the answer is the same as for any question of the form, ';What is the purpose of %26lt;feature x%26gt; in %26lt;organism y%26gt;?';





No purpose. The humans who survive tend to have finger and toe nails. That's all. It is not necessary for finger and toe nails to provide a competitive advantage, but it helps. Features that don't provide the organism with an advantage are called ';vestigal.'; I would guess that our toenails are vestigal. (even some of our TOES are vestigal). On the other hand, I find my fingernails to be pretty useful at times. (e.g., to open my pocket knife.)





Often the same genes that control the expression of a useful feature may be linked to a vestigal feature as well. I am no geneticist, but I bet that the genes that determine our fingernails have a lot in common with the genes that determine our toenails and vice versa. So, even though our toenails are not so useful, we probably will continue to have them for as long as we have fingernails.





If you're a fan of Stephen Jay Gould, then you believe as I do that most so-called ';higher'; organisms (us included) are evolutionary dead ends. In a practical sense, that means that when the last human dies, he/she probably still will have finger and toe nails.Why do we have finger/toe nails?
They evolved from claws. Claws were versatile, being used as weapons, climbing/gripping aids, and in food preparation.





Fingernails serve similar purposes. They can be used as weapons (scratching someone), for better grip (i.e. opening the flip lid on a ketchup bottle), and for food preparation (peeling fruit, etc).
They protect our fingertips. They give support to our fingertips as well. Try pressing against the tip of your finger. Do you feel the strength it has to not bend backwards? Now imagine what would happen if you did the same thing without any fingernail. Your finger would be kind of ';mushy'; so it wouldn't have any strength to be able to grip something properly.

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