Puberty

Encyclopedia of Psychology

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Hormone surge triggers puberty

A point in child development known as adrenarche-the beginning of adrenal androgen activity-may represent the beginning of the process of puberty. Two University of Chicago researchers, Dr. Martha K. McClintock and Dr. Gilbert Herdt, believe that puberty is triggered by dihydroepiandrosterone (DHEA), a hormone produced by the adrenal glands.

According to data the two gathered from three separate studies, DHEA levels begin to increase at around the age of six and reach a critical level around age 10. The researchers characterize these hormonal changes as triggering a number of cognitive, emotional, and social changes in around fourth or fifth grade. Students in these grades begin to engage in boy-girl teasing, exhibit a significant increase in abstract reasoning skills, and experience vulnerability to embarrassment. The three studies also gathered data on subjects' (who were mostly in their mid 30s) first recollected feelings of sexual attraction. The mean age reported by the subjects was around 10 or 11. This finding has led the researchers to postulate that sexual development moves along a continuum, beginning with attraction, progressing to desire, and leading to the willingness and readiness to act on the desire. McClintock, quoted in the New York Times, noted: "Our culture regards middle childhood as a time of hormonal quiescence. Freud called it 'latency.' But actually a great deal of activity is going on."

The word puberty is derived from the Latin pubertas, which means adulthood. Puberty is initiated by hormonal changes triggered by a part of the brain called the hypothalamus, which stimulates the pituitary gland, which in turn activates other glands as well. These changes begin about a year before any of their results are visible. Both the male reproductive hormone testosterone and female hormone estrogen are present in children of both sexes. However, their balance changes at puberty, with girls producing relatively more estrogen and boys producing more testosterone.

Most experts suggest that parents begin short and casual discussions about puberty with their children by the age of seven or eight. Offering the child reading materials about puberty can impart information to the young person without the awkwardness that may characterize the parent-child conversations. Parents can then offer their children opportunities to ask questions or to discuss any aspects of puberty and sexuality that may arise from their reading.

The first obvious sign of puberty is a growth spurt that typically occurs in girls between the ages of 10 and 14 and in boys between 12 and 16. Between these ages both sexes grow about nine inches. The average girl gains about 38 lb, and the average boy gains about 42. One reason for the awkwardness of adolescence is the fact that this growth spurt proceeds at different rates in different parts of the body. Hands and feet grow faster than arms and legs, which, in turn, lengthen before the torso does, all of which create the impression of gawkiness common to many teenagers. In addition, there can be temporary unevenness of growth on the two sides of the body, and even facial development is disproportionate, as the nose, lips, and ears grow before the head attains its full adult size. The growth spurt at puberty is not solely an external one. Various internal organs increase significantly in size, in some cases with observable consequences. Increases in heart and lung size and in the total volume of blood give adolescents increased strength and endurance for athletics and for recreational activities such as dancing. (During puberty, the heart doubles in size.) Teenagers' ravenous appetites are related to the increased capacity of the digestive system, and the decrease in respiratory problems (including asthma) is associated with the fact that the lymphoid system, which includes the tonsils and adenoids, actually shrinks in adolescence. Yet another change, the increase in secretions from the sebaceous glands, triggered by the growth hormone androgen, is responsible for acne, which affects about 75% of teenagers. The excess oil from these glands clogs pores, and they become inflamed, causing the reddening and swelling of acne.