Hair is one of the defining features of the taxonomic class, Mammalia. All mammals have hair, with the exception of some dolphins. They too are born with some hair around the nose, but it falls off soon after birth.
Hair consists of a shaft that protrudes above the skin and a root sunk in a pit called the follicle. A few cells at the base of the hair are living cells; all the rest are dead. The living cells are responsible for the growth of hair.
Hair and nails in mammals are made of keratin. The nails grow in shafts and hair grows in fibres. A rhinoceros’s horn is made of keratin, growing in shafts like the nail.
Hair is a thread like out growth on the outer skin. It forms a thick coat for most mammals. Instead of a coat, rhinoceroses, elephants and whales have bunches of bristles scattered over the body. A porcupine’s quills are actually just enlarged hairs. Humans are among the most hairless mammals.
The coat of hair serves mammals in many ways. It assists in regulating the body temperature by insulating it against the cold and conserving body heat. It also plays a role in cooling the body when the weather is too hot. The coat is also an important form of camouflage, attraction and sexual recognition. Nocturnal animals have special hairs called whiskers that act as sensory receptors.
Human beings have hair of different types. The first growth starts in the womb when the foetus is about months. This is called lanugo. It is a downy growth with each hair being very slender. It is shed either just before or after birth. The next growth of fine un-pigmented hair starts from the first month of life and covers most parts of the body. Terminal hair appears at puberty. It is more highly pigmented, thicker and coarser. On males it appears on the face too. The hair on the eyebrows, eyelashes and scalp hair develops quite early in life.
The length of hair in different parts of the body differs, based on the growth cycle of the hair follicle. Individual differences are attributed to genetics.
The growth cycle of hair has three stages or periods. Hair grows during the anagen period. Growth stops in the catagen period, when the outer root sheath shrinks, cutting it off from the blood supply and cells that produce new hair. The telogen period is a rest period at the end of which the hair falls out and the cycle starts again.
Hair is called our ‘crowning glory’. If you said that our fur was our crowning glory, your English teacher may correct you, but your science teacher certainly would not. Hair and fur are chemically indistinguishable. They are exactly the same thing.
People think that animals have fur and people have hair. Some think that animal coats are short and do not qualify as hair. Sometimes people think that human hair grows continuously while animal hair stops growing once it reaches a certain length. These notions are absolutely inaccurate. The hair growing from the human scalp has an average anagen period of 2 to 7 years after which the hair will not grow any longer. The period differs from person to person. A period of 2 months means the head will never have long hair and the Rapunzel like tresses indicate a growth period of about 10 years.
This phenomenon is also seen in animals. Some breeds of dogs, like poodles, have very long coats. They have an anagen period that lasts much longer than that of the short coated Labrador.
So the answer to the question “What is the difference between hair and fur?” is simply