The wonderful world of human nails

Along with our skin and hair, nails are part of what is called integumentary system. This system protects the body from damage and infection. So nails are not there just to help us scratch our head or put polish on them, they are miniature shields for the fingers and toes. Let’s learn a bit more about them.  

Structure of the nail 
Nails have four main parts: matrix, nail plate, nail bed, and the skin around the nail. Nail cells grow continuously from a little pocket at the root of the nail bed called the matrix. What we see as nail is the visible portion of the matrix. Since it is pale and crescent shaped, it’s called ‘lunula’, Latin for ‘little moon’. Fingernail cells are made of a protein called keratin, the same as hair. The flat, hard and smooth surface of the matrix is the nail plate. And beneath is the soft and fleshy nail bed. Surrounding the matrix is the cuticle, a semi-circle of skin that. The skin just underneath the end of the fingernail is the hyponychium. If we trim our nail too short, this extra sensitive portion gets exposed.   

Rate of nail growth  
Nail grows at the rate of 0.01 mm per day, i.e. 3 to 4 mm per month. Interestingly, they grow more quickly during day and in summer, probably because sunlight produces nail-nourishing vitamin D. Men’s nails grow faster than women’s, and the mail on the little finger grows slowest. If we lose a fingernail, it will take 6 months to grow back, and a toenail will take 1 ½ years. Nails stop growing only after we die.  

Evolution of nails 
Our primate ancestors had claws, also made of keratin, which they used to climb trees. Researchers point out that humans started using tools 2.5 million years ago, and started clenching the fist to hold and strike with these tools. That’s when our claws started reducing and marked the beginning of the evolution of the nails. And while our nails protect our fingertips, they have actually ended making the skin and flesh below the nails more tender and sensitive.