If a nine year old grows two hairs [in the pubic region] the growth should be attributed to a mole [and not as a sign of sexual maturity]. [If these hairs grow] from the age of nine years and one day until twelve years and one day, and they are still there [when the child reaches twelve, one opinion is that they should be attributed to a] mole, and Rabbi Yossi bar Rabbi Yehuda says they are a sign of sexual maturity. [If these hairs grow] when the child is thirteen years old and one day, then everyone agrees they are a sign of sexual maturity...(Kiddushin 16b)
This interest in the sexual development of children might be unseemly, but it had a very legitimate purpose. Certain legal rights are given to a woman once she reaches puberty and leaves the legal status of a child. It was therefore necessary to identify when, exactly a girl enters legal adulthood. Hence the talmudic discussion.
In a related vein, pediatricians and endocrinologists need to understand the natural process of puberty in order to identify a medical problem that needs treating. They too developed measures of sexual maturity, as we will see below.
Pre-Modern Descriptions of Puberty
The way in which children develop into adults has fascinated us for centuries. In fact, the earliest surviving statement on human growth dates back to the sixth century BCE, (not long after the prophet Jeremiah lived) and is by the Athenian poet Solon. One critic described his poem as combining "scientific sense with philosophical probability (if not, regrettably, with poetic elegance)." Here is Solon:
A young boy acquires his first ring of teeth as an infant and sheds them before he reaches the age of seven years. When the god brings to an end the next seven year period, the boy shows the signs of beginning puberty. In the third hebdomad, [ a period of seven years] the body enlarges, the chin becomes bearded and the bloom of the boy's complexion is lost. In the forth hebdomad physical strength is at its peak and is regarded as the criterion of manliness; in the fifth hebdomad a man should take thought of marriage and seek sons to succeed him. In the sixth hebdomad a man's mind is in all things disciplined by experience and he no longer feels the impulse to uncontrolled behavior. In the seventh he is at his prime in mind and tongue and also in the eighth, the two together making fourteen years. In the ninth hebdomad, though he still retains some strength, he is too feeble in mind and speech for the greatest excellence. If a man continues to the end of the tenth hebdomad, he has not encountered death before due time.
Hippocrates believed that puberty could be delayed in areas where "the wind is cold and the water is hard". Rabbi Shimon ben Gamliel (d. 70 CE) would have agreed, because he thought that the growth of pubic hair was hastened in those who used the bathhouse regularly. But it is especially interesting to compare Aristotle's writings on puberty with those of the Talmud (which of course were codified several hundred years later).
In man, maturity is indicated by a change in the tone of the voice, by an increase in size and an alteration in appearance of the sexual organs, and also by an increase in size and alteration in appearance of breasts, and above in the hair growth above the pubes.
Aristotle (d. 322 BCE) seems to have put a lot of weight on the growth of pubic hair, just like the rabbis in the Talmud many years later. Galen, who died in 199 CE, was cautious about timing the onset of puberty: "Some begin puberty at once on the completion of the fourteenth year, but some begin a year or more after that" (De Sanitate Tuenda, or p288 of this translation). Jumping forward several centuries, we find that girls in Tuscany in 1428 were allowed to marry aged eleven and a half, although they were forbidden to live with their husbands until they were twelve. However the Bishop of Florence (later canonized as Saint Anthony) declared that cohabitation was allowed "provided the girl had reached puberty."
According to Celia Roberts from Lancaster University in the UK, the first textbook on growth, written in 1729 by Prussian physician Johann Stoller, was entirely theoretical and contained no actual measurements of children. They were not measured until 1754, when the physician Christian Jampert presented a thesis based on measurements of children in a Berlin orphanage. Roberts continues:
In 1777 the first longitudinal study of growth was reported in George LeClerc Comte de Buffon’s Natural History. Based on measurement of his assistant Phillip Gueneau de Montbeillard’s son from birth to adulthood (1759–77), this study confirmed the concept of a ‘pubertal growth spurt’ and seasonal changes in growth rate. Some 60 years later Belgian mathematician Adolphe Quetelet combined a mathematical approach with empirical data on children’s growth, using data from measurements of his own children.
The Tanner Scale
Today, the stage of sexual maturity in children is most commonly measured using the Tanner scale, described by the British pediatrician James Tanner, who died in 2010. (He wrote a fascinating History of the Study of Human Growth as a sort of a hobby, but his day job was working as a Professor at the Institute of Child Health in London.) Here is how Tanner described his scale in boys, (from his original paper published in 1970):
Stage 1: Pre-adolescent. The velus [sic] over the pubes is no further developed than that over the abdominal wall, i.e. no pubic hair.
Stage 2: Sparse growth of long, slightly pigmented downy hair, straight or slightly curled, appearing chiefly at the base of the penis. This stage is difficult to see on photographs, particularly of fair-headed subjects...
Stage 3: Considerably darker, coarser, and more curled. The hair spreads sparsely over the junction of the pubes.
Stage 4: Hair is now adult in type, but the area covered by it is still considerably smaller than in most adults. There is no spread to the medial surface of the thighs.
Stage 5: Adult in quantity and type, distributed as an inverse triangle of the classically feminine pattern. Spread to the medial surface of the thighs but not up the linea alba or elsewhere above the base of the inverse triangle.
Tanner also described five stages of breast development in girls, in a paper he published in 1969.
Stage 1: Pre-adolescent; elevation of papilla only.
Stage 2: Breast bud stage;elevation of breast and papilla as a small mound, enlargement of areola diameter.
Stage 3: Further enlargement of breast and areola, with no separation of their contours.
Stage 4: Projection of areola and papilla to form a secondary mound above the level of the breast.
Stage 5: Mature stage; projection of papilla only, due to recession of the areola to the general contour of the breast.
And here is the distribution of the age on reaching each of the various signs of puberty, at least as Tanner found them in his sample of 192 white British girls in the 1960s. It shows, for example, that most of the girls reached stage 5 breast growth (B5) a little after their fifteenth birthday.