The average human has as much hair as the hairy primates, but only it is short and fine. Each hair on the scalp has a life span of about three years. Eyelashes have a life span of about 150 days. The soft down-like hair of the newborn sometimes reappears on the body of the aged. We blink every 2- 10 seconds. Each blink lasts for 0.3-0.4 seconds. An infant does not blink at all in the first few months of life. A child can bring its eye inwards towards the nose to focus on an object just 3 inches from its face. By the time an adult is 30, the closest distance that he/she can focus under these circumstances is 5 and a half inches