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The physical growth and the changes of puberty mark the onset of adolescence (Lerner & Steinberg, 2009). For both boys and girls, these changes include a growth spurt in height, growth of pubic and underarm hair, and skin changes (e.g., pimples). Hormones drive these pubescent changes, particularly the increase in testosterone for biological males and estrogen for biological females.[1] Puberty is a developmental period in which hormonal changes cause rapid physical alterations in the body, culminating in sexual maturity. Although the timing varies to some degree across cultures, the average age range for reaching puberty is between 9 and 14 years for biological females and between 10 and 17 years for biological males (Marshall & Tanner, 1986). This period of physical development of the adolescent age 9-13 is divided into two phases.[2]
It also involves height increases from 20 to 25 percent. Puberty is second to the prenatal period in terms of rapid growth as the long bones stretch to their final, adult size. Biological females grow 2–8 inches (5–20 centimeters) taller, while biological males grow 4–12 inches (10–30 centimeters) taller.
Secondary sexual characteristics are visible physical changes not directly linked to reproduction but signal sexual maturity. The growth spurt for biological females usually occurs earlier than that for biological males, with some males continuing to grow into their 20s. For males this includes broader shoulders, an enlarged Adam’s apple, and a lower voice as the larynx grows. Biological males typically begin to grow facial hair between ages 14 and 16, which becomes coarser and darker, and hair growth occurs in the pubic area, under the arms, and on the face.
For biological females the enlargement of breasts is usually the first sign of puberty and, on average, occurs between ages 10 and 12 (Marshall & Tanner, 1986). Their hips broaden and pubic and underarm hair develops and becomes darker and coarser. Adolescents regardless of gender experience a rapid growth spurt during this stage. Adolescents may begin shaving during this time period as well as showing signs of acne on their faces and bodies.
Acne is an unpleasant consequence of the hormonal changes in puberty. Acne is defined as pimples on the skin due to overactive sebaceous (oil-producing) glands (Dolgin, 2011). These glands develop at a greater speed than the skin ducts that discharge the oil. Consequently, the ducts can become blocked with dead skin and acne will develop. According to the University of California at Los Angeles Medical Center (2000), approximately 85% of adolescents develop acne, and biological males develop acne more than biological females because of greater levels of testosterone in their systems (Dolgin, 2011). Hormones that are also responsible for sexual development can also wreak havoc on the teenage skin.[3]
A major milestone in puberty for biological females is menarche, the first menstrual period, typically experienced a