Though we like to think of puberty as a singular and sudden event, the truth is that it’s more of a gradual process that is occurring in ways you can’t visibly see. “Puberty actually begins before it is physically expressed,” writes Kent Van De Graaff (2000). Humans and apes are the only two species known to undergo what is known as adrenal puberty (changes in hormones secreted by the adrenal glands), which is separate from gonodal puberty (growth and maturation of the reproductive organs). Adrenal puberty is a much more extended process that can begin as early as age 5 or 6 when the adrenal glands begin releasing more androgen into the brain (known as adrenarche).
“Early adolescence starts well below the teens for both sexes,” write Dorothy Babcock, R.N., M.S., & Terry D. Keepers. “Marked increases in the sexual hormones are noticeable in the blood stream of girls from the age of eight on. Boys show evidence of similar increases about two years later. These changes in the blood chemistry are followed by the beginning appearance of the secondary sex characteristics. Girls develop nipples which look like mosquito bites, and pubic down (fine light hair). Boys’ testes start to enlarge.” (Babcock & Keepers, 1976, p. 154)
How long does puberty last?
Gonadal puberty, which is the physical changes we can see, typically lasts between two and four years.
Physical body changes that occur during puberty
Prior to puberty, male and female children are pretty much the same physically aside from the outward appearance of the genitals. When puberty strikes, there are significant changes in body composition. “Sexual changes are usually thought of as the only features of puberty,” writes Kent Van De Graaff, “but major musculoskeletal changes take place as well.” (2000, p. 758) During puberty boys move toward a body ratio of 40% protein to 15% fat, whereas girls develop a ratio that is 23% protein to 25% fat. Boys develop more muscle mass whereas girls tend to put on weight around the hips and thighs. Strength and athletic differences between the genders start to widen during puberty. Prior to puberty, boys and girls can play on co-ed sports teams without the girls being significantly disadvantaged. After puberty it’s harder for girls to compete against boys, and they would generally be at a disadvantage.
Puberty & sexual identity in children
There’s a common misperception that puberty marks the onset of a child’s sexuality. In truth, children are sexual beings from the very beginning, born with fully functioning sexual organs and the capacity to experience both arousal and orgasm. Sexual desire also emerges very early in life, and can be seen as young as age 3 or 4, in the form of what parents would more commonly refer to as “crushes.” This is why gays and lesbians often describe knowing they were different from a very early age.
Puberty marks the completion of this sexual development, not its beginning. However, prepubescent sexuality is more diffuse, and lacks the same hormonal intensity. As children approach and enter puberty these hormones increase, giving them a sexuality more on par with adults.
The Tanner Scale Stages of Puberty
For medical and/or legal purposes, stages of puberty are often defined according to what is known as the “Tanner Scale”:
Tanner scale stage 1:
Stage 1 is prepubescent, although hormonal and psychological development is still taking place.
Tanner scale stage 2:
Stage 2 of the Tanner scale marks the beginning of pubertal development. It involves the growth of sparse, slightly pigmented pubic hair along the base of the penis or vulva. In girls there’s also the appearance of breast buds, and the beginning of growth in both male and female genitalia.
Tanner scale stage 3:
Pubic hair darkens and becomes thicker, and begins to extend laterally. Growth in the breasts and genitalia continue.
Tanner scale stage 4:
Pubic hair is similar or identical to that of an adult, but covers an area smaller than an adult. For example, there’s no spread to the medial surface of thighs. Growth of the genitals has typically been completed.
Tanner scale stage 5:
Stage 5 is essentially an adult, with pubic hair and genitals indistinguishable from an adult. Adolescents may reach this stage as early as 13, or as late as 17 or 18. (See also: childgrowthfoundation.org/wp-content/uploads/2020/03/Puberty-and-Tanner-Stages_v2.0.pdf)
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