It would seem that the conditions existing among Europeans are the primitive state, as with the majority of animals also puberty begins before the cessation of growth.
Reche reports further that, corresponding to the late puberty, the secondary sexual characteristics also appear exceptionally late in Matupi children. This is the chief reason why the boys and girls, especially as they are small, appear remarkably young even shortly before maturity, and why their age seems much less than it actually is. The first beginning of the change from the areola mamma to the budding breast shows itself among the Matupi girls not before the sixteenth year; the development of the breast seems to coincide with the first menstruation. Axillary hair did not appear in sixteen-year-old Matupi girls, with one exception; and it was scanty in those seventeen years old, though it is generally copious in adults. There was also no trace of a beard in seventeen-year-old boys, though it is well developed in the older men. It must be added that the late differentiation of secondary sexual characteristics is also noticeable among other coloured races, as, e.g., among the Philippines and other Indonesian races.
Among the Papuans of New Guinea also sex maturity occurs late. As Richard Neuhaus wrote, according to information given by missionaries who have lived for a long time among the natives on Tami and among the Jabim, the first menstruation generally appears in the fifteenth to sixteenth year. Young males look very undeveloped up to the sixteenth year. Neuhaus thought this late maturity was the result of bad feeding, though it does not appear from his other descriptions that the economic conditions of the Papuans are especially unfavourable.
A. E. Jenks reports of the Igorots on Luzon that boys as well as girls attain puberty at a late age, generally between fourteen and sixteen years. The civilised Ilkano people settled among the Igorots definitely declare that the girls do not menstruate before they have reached the sixteenth or seventeenth year. A considerable error as regards their age seems to be excluded with these people, who have lived a long time under European influence.
Of the Andamanese, a pigmy race, Portman and Molesworth write that puberty appears in boys and girls round about the fifteenth year. Bodily growth is finished at eighteen years, and is in any case after maturity very trivial.
Eugen Fischer makes the following statements about the Bastards in German South-west Africa: "In one family five out of six daughters menstruated for the first time at the age of fifteen, one at the age of sixteen. One Bastard woman had first menstruated at the age of seventeen, three of her daughters at thirteen, the fourth, who was anæmic, at seventeen. Another Bastard woman, who herself had her first menstruation at fifteen, had two daughters from a white man who had reached puberty at sixteen and seventeen years of age. A girl with distinct anæmia stated that she had had her first period at sixteen years, her sister even as late as eighteen," Fischer knows of three girls that became mature at sixteen, fourteen, and thirteen years. L. Schultze reports that with the Hottentots the first menstruation appears, as a rule, between the ages of thirteen and fifteen.
There is, unfortunately, no information to be had about the negroes with regard to this subject. The puberty rites practised by them give no clue to the real age at the advent of puberty.
Aleš Hrdlička (pp. 125-129) tried to determine the age of puberty among Indian girls of the south-west of the United States by their height, as definite statements of age are not to be had. This method is not without objection, for it is certain that individuals who have attained puberty are decidedly taller than persons of the same age who have not reached maturity. Hrdlička found that of those examined in the twelfth or thirteenth year one-third of the Apache girls and as many as three-quarters of the Pima girls had already menstruated. In the age class of thirteen to fourteen years four-fifths of the Apache and nine-tenths of the Pima girls had already menstruated, while of forty-six older girls only one had not yet attained puberty. The first signs of breast development were noticed by Hrdlička in clothed Indian maidens whose ages he estimated to be from eleven to twelve years. But it was only between fifteen and seventeen that the girls acquired the typical womanly form; until then they have, as Hrdlička says, "a somewhat male appearance." In youths the beard begins to grow at the fifteenth or sixteenth year. The climate is moderate in the country of the Apache and Pima Indians; the days are decidedly hot in the low-lying regions, but the nights are generally cold in these regions, even in summer.
In comparison it may be noted that, according to H. P. Bowditch's investigations in Boston, nearly four-fifths of the white girls born in America mature between the thirteenth and seventeenth year. Puberty is reached relatively most often between the ages of fourteen and fifteen, though over 40 per cent. of 575 girls examined had not yet menstruated at the completed fifteenth year.
Within one and the same race the conditions of life seem to have a great influence on the age of puberty and bodily development. Unfavourable conditions produce a retardation of puberty; favourable conditions accelerate it. This may be the chief cause why the beginning of puberty varies individually by several years.