The human body is wonderfully adaptive, particularly in the ways it seeks to protect itself.
Calluses are one such protective mechanism.
Calluses are areas of skin that grow thick in response to repeated pressure and friction. They are the body's way of protecting its skin, or the structures beneath it, from injury. Calluses will form on the skin of any part of the body that is exposed to excessive pressure or friction. Sometimes calluses are useful. Laborers and people who work hard with their hands typically develop thick calluses that protect their fingers and palms from nicks, scratches and cuts, and anyone who has ever tried to play a stringed musical instrument will tell you it's a painful process until you develop strong calluses on your fingertips.