The parabolic cycle of stature shows us which is the most favourable period for the reproduction of the species; it is undoubtedly that period that stands at the highest apex of the curve, and at which the organism has reached an almost absolute peace, as if forgetful of itself, in order to provide for its eternity. When it has completed its period of evolution, during which the organism shows that it has not yet matured; and before the commencement of involution, in which period the organism is slowly preparing for departure—that is the moment when man may or rather ought to procreate his species.
Careful forethought not to produce immature or feeble fruit, will form part of the coming man's regard for his posterity. A new moral era is maturing, that is giving birth to a solidarity, not only between all living beings, but including also those future beings who are as yet unborn; but for whose existence the living man of to-day is preparing through his care of his own strength and his own virtue. To have intentionally begotten a son better than himself will be a proud victory for the man who has attained the higher sexual morality; and such pride will be no less keen than that of the artist, who by perfecting his marvelous talents has created a masterpiece.
The statistics collected by Quétélet demonstrate that "too precocious marriages either occasion sterility or produce children that have a smaller probability of living."
They prove furthermore that the number of children who die is largest in marriages contracted at the age of sixteen or earlier, and becomes lowest among the children born of marriages contracted between the years of 29 and 32. During these years also the parents are most fertile: as is shown by the following tables:
SANDLER'S FIGURES BASED ON THE FAMILIES OF ENGLISH PEERS
| Age of parents at marriage | Percentage of deaths of children before attaining marriageable age | Average births to each marriage | Percentage of births to each death |
|---|---|---|---|
| 15 years | 35 | 4.40 | 0.283 |
| 16-19 years | 20 | 4.63 | 0.208 |
| 20-23 years | 19 | 5.21 | 0.188 |
| 24-27 years | 12 | 5.43 | 1.171 |
| Age at the time of child's birth | Percentage of deaths to each birth | Average number of births in one year of marriage |
|---|---|---|
| 16 years | 0.44 | 0.46 |
| 17-20 years | 0.43 | 0.50 |
| 21-24 years | 0.42 | 0.52 |
| 25-28 years | 0.41 | 0.55 |
| 29-32 years | 0.40 | 0.59 |
The results of a recent research show that famous men have hardly ever been the first-born, and that the great majority were begotten of parents who were at the time between the ages of 25 and 36 years.
Variations of Stature with Age, According to the Sexes.—The general laws of the growth and involution of stature are pretty nearly the same for the two sexes. The female stature, beginning at birth, averages throughout life somewhat less than the male.
But since the development of puberty takes place earlier in woman than in man, the female child manifests the characteristic increase in stature at an earlier age than the male; consequently at that age (about eleven) she overtakes him, and for the time being both boy and girl are equal in stature. But as soon as the boy enters upon the period of puberty, he rapidly surpasses the girl, and his stature henceforth steadily maintains a superiority of about ten centimetres (nearly four inches), as is shown by the deviations between the two parabolic curves, representing the variations of stature in the two sexes. Even the involution of stature occurs precociously in women, as compared with man.