Originally Posted by google Answers
"Why do we have fingernails?"
"Our fingernails are similar to claws or hooves found in other
animals. More generally called “digital appendages”, they are enlarged
keratinized structures (the same stuff that horns are made out of)
that protect the tips of the fingers and toes in most vertebrate
species, or aminals with backbones. Fingernails are broad, and
slightly curved, and mostly cover the top surface of our fingers.
In other species, this structure is slightly different - for example,
crocodiles have a thimble-shaped structure that covers the whole tip
of their digits, whereas hawks and owls have talons, highly recurved
claws specialized for prey capture, and horses and cows have hooves
that protect their feet.
So, the reason we have fingernails is simply that everyone in our
family tree has some sort of digital appendage that probably served to
protect fingertips in our distant ancestors, and each group has
evolved modifications that best fit their needs for a particular
environment. Fingernails in monkeys, apes and humans always cover only
one side of the fingertip and thus they protect but don’t limit the
motion or sensitivity of our fingertips."