The downward movement
In 1860, the maiden of maturity occurred at age 17. In 1910 — already in 14. Half a century later, in 1960-m to year — in 11 years. For a hundred years, girls have begun to Mature 6 years earlier. What was, then? Since then, the trend has slowed, but gradually takes its toll: in 2019 puberty started on average 10.1 years. The boys, as usual, a little behind girls as in speed of development and rate of acceleration — but the pattern holds for them: the beginning of puberty has shifted over the past 15 years at least for a few months.
To find reliable data on the boys challenging the majority of researchers working with the girls. There is a reason. Puberty is not done overnight, it is a long multistage process. In order to document the progress of the maturation process for conditional break points, for example, so arranged scale Tanner: the five stages of development depending on the size, shape, and body hair growth of the external genitalia. Now most often the words “beginning of puberty” refers to stage 2 according to Tanner — the appearance of the first characteristic hairs.