THE PHYSICAL CHANGES OF PUBERTY
Puberty (from Latin puber: adult) is the period of life when boys and girls turn into young men and women. That is to say, their bodies begin to show the secondary male and female sexual characteristics, and they become capable of reproduction. These physical changes occur under the influence of various hormones, especially the gonadal hormones. (For details, see "The Process of Sexual Differentiation.")
Puberty arrives at different ages for different individuals, and it may last between one and several years. Much depends on hereditary factors, diet, climate, cultural influences, and emotional conditions. In recent decades, the age of puberty seems to have been lowering for both sexes. However, now as before, the physical maturation of females begins somewhat earlier than that of males. In girls, the enlargement of the breasts and the growth of pubic hair start at an average age of 10 to 11 years, and the first menstruation occurs at about 11 to 13 years. In boys, the enlargement of the testicles and the growth of pubic hair normally begin during the ages of 12 to 16 years, and the first ejaculation occurs from 13 to 17 years of age.
Since the physical changes of puberty may appear early or late, quickly or slowly, individuals of the same chronological age may find themselves in very different stages of development. For an adolescent, this is often a matter of great concern. Boys may worry about their height, the breadth of their shoulders, the strength of their muscles, the size of their penis. Girls may be afraid of growing too tall, and they may anxiously measure the size of their breasts and the width of their hips. Indeed, during this period, young people tend to become extremely sensitive and self-conscious about their appearance. In many cases, the hormonal changes in the body produce acne, an inflammatory skin disease which, although otherwise harmless, may temporarily disfigure the face, neck, and back. Some adolescents also consider themselves unattractive because they seem to be gaining too much weight. Still another potential source of embarrassment is the heightened sexual responsiveness. For example, boys may resent the fact that they have sudden erections at very awkward moments. To some extent, this may also have happened in childhood. However, with the arrival of puberty these responses occur more often, and they now become more clearly defined as sexual. Paradoxically, the sexual awareness of girls lags well behind that of boys. While the secondary sexual characteristics may appear much earlier in females than in males, the female capacity for sexual arousal and orgasm often develops much later. There may be some biological reason for this, but social conditioning undoubtedly also plays a role.