Hair is the second fast growing tissue in the body only after bone marrow. Hair grows about 1 to 1.5 cm every month. On average, the lifespan of a human hair is 2 to 7 years. Kids lose on average 90 hairs everyday, which rises to 120 by old age. Most people normally shed 50 to 100 hairs a day. This usually doesn't cause noticeable thinning of scalp hair because new hair is growing at the same time.