What is the reason for finger nails and toe nails?

One theory about fingernails and toenails suggests that
they are designed to protect the delicate nail bed. This supposition has been dismissed
by many doctors, who point out that people who permanently lose nails develop tougher
nail beds. It seems more likely that the delicate tissue or quick under the nail evolved
in response to the presence of fingernails, rather than the other way
around.

The more likely reason for the presence of
fingernails and toenails is that they are useful. Fingernails help humans to scratch
things, peel fruit, open things, pick away the outer layers of other edibles, undo
knots, and perform a variety of other tasks. In a more distant past, fingernails
probably assisted humans with the capture of body lice, as is still seen among the great
apes. When the feet were used more like hands, toenails served a similar function,
helping humans to open vital food objects, strip bark to build structures, and other
such things.

Fingernails help the hands to grip things and
start rips and tears. If you remain unconvinced of the usefulness of fingernails, try
trimming them to the quick or covering them in tape for a day. Having fingernails out of
commission makes it much more difficult to scratch itches, clean the hair and scalp,
open foods, and perform a wide variety of delicate manipulations with the hands.
Toenails may not be quite as useful, but when you imagine the feet as hands, their
presence makes much more sense.

Like the hair, fingernails
are made out of keratin, a type of protein. If the nails are weak and brittle, higher
amounts of keratin should be ingested: a common source is gelatin, a food product
derived from the hooves of animals, which also contain keratin. An increase in the level
of keratin consumed will lead to healthier skin and nails.