Why, Armpit Hair, Why?

What is the purpose of armpit hair? Researchers believe that, since it appears at puberty, one of its roles is to signal that its owner has indeed reached puberty. Simple enough. Also, the armpits have a certain type of hair follicle with glands that produce pheromones, which are chemicals that are believed to attract the opposite sex. However, skin bacteria breaks these pheromones down into something much smellier and less seductive.

Male Growth During Puberty? Like a Weed

Growth for pubescent boys establishes a pattern about as unpredictable as a teenager's time of awakening each morning. There are sudden bursts of growth followed by seeming inactivity, leading to frustration on the part of the boys who wonder if that first spike in growth was also the last. This is also a bad stretch of years for parents who must fork out money for their son's clothes one day that may seem ill-fitting the very next.

Most boys, though, will take growth any way they can get it. After all, they don't want to have girls their age towering over them for the rest of their lives. Once boys start really growing, it doesn't take too terribly long to catch up with the other gender. Between the ages of 12 and 16, boys grow in height as much as a full foot (.3 meters). Weight gain in this same period can vary from 15 to 65 pounds (6.8 to 29.5 kilograms) [source: University of Virginia].

The first parts of the body to really gain in size are the arms, legs, hands and feet. These extremities grow at a faster rate than the rest of the body. This explains why boys going through puberty are bumping into people, dropping things and tripping over flat pieces of pavement. Clumsiness is normal and fortunately goes away once the rest of the body catches up.

During puberty, a boy's face changes shape. The chin gets longer and the nose gets thicker. The actual muscle tissue and the bone it rests against are changing as well.

Other changes -- not all of them visible -- are taking place. Blood pressure increases during puberty. This is a good thing, because there is more real estate for blood cells to travel to as these growth spurts occur. Body odor increases as the composition of sweat changes. When the bacteria present on the skin comes in contact with the ammonia and urea in the sweat, it can create a smell that attracts others about as effectively as acne and a cracking voice. A boy's pulse and metabolism also slow down, a signal that the body is making changes to prepare for the long haul.

The premature appearance of puberty in boys can lead to problems, such as higher lifetime risk of testicular cancer and problems attaining full growth due to premature closure of the bones' growth plates. If a very young boy is showing signs of puberty, a doctor should be alerted.