How Male Puberty Works

While puberty begins and ends at different times for different people, puberty always begins with the appearance of a substance called gonadotropin-releasing hormone (GnRH) in the body. The release of GnRH is controlled by the hypothalamus, the same part of the brain that regulates your temperature and your sleep cycle, as well as your senses of hunger and thirst.

With that in mind, let's take a look at the different stages of puberty. While not strict guidelines, these stages provide a pretty good idea of the overall appearance and occurrence of the different changes that happen in a male's body during puberty.

Boys generally begin puberty sometime around age 10, though it isn't uncommon for it to begin as early as age 9 or as late as age 12. GnRH is released, the testicles begin to mature and an initial growth spurt may occur (with average growth being around 2 inches (5.1 centimeters) a year). Although the growth of the scrotum and testicles is one of the first outward signs of puberty, boys at this stage are still unable to reproduce. There may also be the appearance of very fine hair in the pubic area. Boys may occasionally experience erections.

The second general stage of puberty usually occurs around age 12 or 13. The testicles continue to grow, and this in turn means that more testosterone will be flowing through the body, spurring more changes. The boy will continue to grow taller rapidly, at a rate of 2 to 3 inches (5.1 to 7.6 centimeters) a year. What little pubic hair exists may begin to gain some color. Erections will become more frequent. The boy's body will begin to take on a leaner, more adult and masculine shape.

The third stage of male puberty occurs around age 13 or 14, but frequently as early as 11 or late as 16. Pubic hair begins to grow darker and fuller, and the penis now begins to grow in length. The testicles continue growing, erections become commonplace and the boy gains in height at a rate of over 3 inches (7.6 centimeters) a year. The voice may begin "breaking" or "cracking." This is when the boy's voice suddenly and uncontrollably changes pitch mid-word or sentence, due to the growth of the larynx and the lengthening of the vocal cords.

Stage four of male puberty commonly takes place when a boy is around 14 or 15 years old. Hair begins showing up in the armpits and on the face, and pubic hair begins to grow coarse. The boy's voice will even out and become deeper. The stage-four boy can use this deeper voice to yell forcefully at the mirror when he sees his new acne, due to his ever-more-oily skin. He begins to grow taller and even faster, at about 4 inches (10.2 centimeters) a year. The penis now grows thicker and continues to lengthen.

The final stage of male puberty occurs anywhere from age 14 to age 18. During this time, a boy will achieve most (but not necessarily all) of his height. His body shape will have evolved to that of a man's -- his shoulders will be broader, his muscles developed and fully formed, his arms and legs and chest proportioned for power and masculine appearance. This is because new muscle fibers are appearing, and all muscle fibers are getting thicker. Pubic hair will spread out to the inner thighs and lower stomach. By this stage of puberty, boys -- make that young men -- will be shaving, and their pubic hair and sex organs will look fully developed. While hair and height and body type will look adult and complete, many males will continue growing and developing into their 20s.

In the next section, we'll take a closer look at the growth process itself.

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.

Although puberty can be humiliating, its actual purpose is to enable sexual reproduction. The process taking place inside a pubescent boy's body to bring about reproductive ability is quite complex. We'll learn the basics of it in this section.

At around age 9 or so, a boy's central nervous system sends out a message: "Change!" First, the hypothalamus releases GnRH. Because this hormone is present in the hypothalamus before puberty, it's believed that a protein named GPR54 helps get the GnRH out of the hypothalamus at the right time. When the GnRH reaches the pituitary gland -- a pea-sized gland located at the base of your brain -- the pituitary gland in turn produces two important hormones: follicle-stimulating hormone (FSH) and luteinizing hormone (LH). These two hormones also exist before puberty, but once the pituitary is triggered by the hypothalamus, these hormones are created in much greater quantities.

Early on in puberty, these hormones (which, along with hormones that trigger development of the testes, are known as gonadotropins) are produced only at night. In later stages of puberty, when growth is going gangbusters, these hormones are being produced around the clock and in greater and greater quantities.

FSH, when it reaches the testes, spurs the growth of seminiferous tubules, which are the channels in the testes in which sperm is produced. Once these tubules are formed and the infrastructure is in place, the body begins producing sperm.

LH, on the other hand, has a different function. It prompts cells within the testes called Leydig cells to produce androgens. Androgens are hormones that affect the development of a male's reproductive ability. Testosterone is the main androgen, though there are many others.

Between the time FSH and LH first reach the testes and the time a pubescent boy can successfully reproduce, the changes we discussed in the puberty stages section (growth of hair, changes in penis length and width) have taken place.

Next, we'll take a look at another scourge of adolescence: acne.

During puberty, a boy's skin on his face, neck, back and chest will eventually begin to overproduce a type of oil called sebum. Sebum is normally a good substance -- it keeps the skin waterproof and fends off harmful bacteria. But too much is definitely not a good thing. Along with excess oil, the pubescent skin is also sloughing off skin cells at a higher rate, and these skin cells -- and the extra oils -- are trying to exit the body by traveling through hair follicles and pores to the surface of the skin. When these pores and follicles get clogged up with this excess matter, there is a pileup as the skin and oil behind the blockage start building up without anywhere to escape. A form of bacteria known as Propionibacterium acnes (P. acnes for short) gets in the mix and causes the blockage to become inflamed. This pushes it outward, creating the visual sensation known as a "zit."

There are many forms of acne, but the most common one is acne vulgaris. Acne vulgaris is responsible for your garden-variety pimples, blackheads, whiteheads and the cyst-looking large bumps. There's pretty much no escaping acne vulgaris -- it afflicts practically everyone at some point, and boys get it worse than girls during puberty. (After puberty, it's a different story: Women have much more trouble with adult acne than men.)

If you're a pubescent boy dealing with acne, this is your best bet: Wash your face gently twice a day, shower immediately after working up a sweat and don't pick at your face. Don't go overboard trying to clean your face, either, because excessive scrubbing and agitating the skin can make everything worse.

Products containing benzoyl peroxide or salicylic acid can help prevent or control acne by drying out the skin, killing bacteria and helping the follicles clear themselves of dead skin cells.

Don't get too stressed out if one thing or another doesn't seem to be helping -- it often takes quite a bit of experimentation before you discover the right cure (or combination of cures). Your doctor or dermatologist will be more than happy to help you in your quest for clear skin (and you can also find out lots more about acne by checking out How Acne Works).

Next, we'll examine a question that has tormented the minds of pubescent girls since the beginning of time: "Why are pubescent boys insane in the brain?"

Puberty doesn't just cause great changes and development in a male's body -- it changes and develops the brain as well. Boys in puberty will begin to show interest in and understanding of abstract concepts and subjects such as justice, politics, philosophy and the arts [source: University of Virginia]. A pubescent boy will also begin planning out a life for himself and establishing dreams and goals to be realized and fulfilled later in life.

With this radical new worldview and altered sense of self comes anxiety and confusion. A young man's prior understanding of himself has now been eradicated, and a new sense of identity must be built from these ruins. The ability to view the world in entirely new ways means that an adolescent must sort out not only who he really is as a mature male, but also how this new identity fits into his new perspective [source: McGrath]. It's no wonder that on most mornings, it seems much easier to just stay in bed and sleep.

By the time a boy i­s experiencing puberty, parents are no longer welcome to accompany him in public, offer advice or breathe. This new independent streak is actually a good development, because this rejection of parents' beliefs, morals and general existence means that the pubescent boy is attempting to find his own way in the world.

Along with new beliefs and new feelings, a growing boy often will form new peer groups [source: University of Virginia]. This will be a time of experimentation, adventure and misadventure. The important thing for parents is to provide a stable home environment, open arms should they be needed, and reasonable guidelines and behavioral expectations.

Though parents should give some extra leeway and show extra patience during these topsy-turvy years, they should also keep an eye out for some of the pitfalls of adolescence, such as depression or substance abuse [source: McGrath]. This period in life can create an overwhelming sense of being lost, and not all boys exit this stage feeling like they've found the answers they need. If parents suspect that teenage experimentation with drugs or alcohol is the beginning of a greater problem, or if problems at school or home aren't being resolved through time and attention, it might be a good idea to encourage your son to talk to a counselor, a doctor or a respected member of your religious community.

When a male passes through puberty (or at least reaches the age for it), many cultures around the world have traditions, customs or ceremonies that mark this passage in the young man's life.

In Quranic teachings, Islamic parents are instructed to teach their sons about responsibility and adulthood and inform them that they will be responsible for their actions from the time of the their first ejaculation. After this act, sons are to pray and perform religious observations as adults do. If a boy has a wet dream, the Quran relates that the son should bathe himself immediately. If a sexual dream occurs without ejaculation, the boy doesn't have to clean himself.

In Judaism, boys become a bar mitzvah (literally "son of the commandment") on their 13th birthday. The event marks the moment when the child is responsible for observing the commandments and all Jewish teachings. Though the status is automatically conferred upon the boy's birthday, often the boy recites a blessing before the congregation or helps in leading a service. Afterward, modern practice has added a celebratory reception that most of us know as "the bar mitzvah," but it's far from a universal practice.

In some parts of the world, such as Malaysia and throughout Southern Africa, boys are often circumcised around the time they reach age 11 or 12, right around the onset of puberty. It's believed that pubescent circumcision was used by some ancient cultures to mimic the genital bleeding experienced by girls. Some Australian aboriginal tribes also incorporate penis incision or piercing into puberty rites, as well as circumcision.

Many cultures involve other forms of trials, ordeals or tests that the boy must successfully pass. Apache boys must take ice baths, while aboriginal Australians sent boys out on long foot journeys, known as walkabouts, where the boy would pick up and perfect hunting and surviving skills. Some Native American tribes also sent young men out on vision quests.

Death isn't uncommon in South African puberty rituals, when boys are separated from the village and effectively starved as part of their initiation. Though most survive this separation, some others die from infection from the circumcision ceremony that follows.

For more articles on circumcision, acne and the female version of puberty, see the links on the next page.