Well, without puberty the human population would go extinct—we have to go through puberty to keep the species going. Other primates also go through puberty. If you’ve ever read about Jane Goodall and her time with the chimpanzees in Gombe, you would have noticed that chimps also go through puberty, but at a relatively younger age, in a shorter time span. Childhood, however, is an important step to puberty. Physical anthropologists believe childhood is the time when humans learn some basics about how to live—how to find food and shelter, for example. In our society finding food and shelter is more about learning things (reading, for instance) that eventually help you get a job to buy food and shelter.
Now, what is puberty? When you reach a certain age (generally between 8 and 13 for girls; 10 and 15 for boys), your brain releases a particular hormone called gonadotropin-releasing hormone. It heads for your pituitary gland. The pituitary gets the message and releases two more puberty hormones into your bloodstream.
These two hormones do different things, depending on whether you’re a boy or a girl. For boys, the hormones signal the testes: start producing testosterone and sperm. Testosterone is what causes most of the changes in boys—the deeper voice, for example. And facial hair! Getting the body to start producing sperm cells is the way men reproduce. No sperm, no offspring. For girls, the hormones head for the ovaries, which contain a set number of eggs that have been there since birth. The hormones signal for the ovaries to start producing estrogen. Estrogen prepares a woman’s body for pregnancy.
So, puberty is basically all these chemical signals moving around inside the body, turning a teenager into an adult. The time frame varies from person to person, but eventually everyone turns into an adult, at least physically! Mentally it might take more time and practice.