Variations in Stature Through the Different Ages
Notwithstanding that growth is an evolution, it manifests itself also by an absolute augmentation of mass; and the linear index of such augmentation is given by the growth in stature, or by its variations at different ages.
This exceedingly important measurement ought to be taken in the case of all pupils; and undoubtedly in the course of time anthropometry will form a part of our school equipment; because, by following the increase of stature in a child, we follow his physical development.
In Chapter VII, in which the technique of the stature is discussed, there is a graphic representation of the annual increase of stature in the two sexes; the upper parabolic line refers to the male sex, and the lower one to the female. On the vertical line are marked the measures of growth, from the base upward, and on the horizontal line the ages. All the dotted vertical lines which rise from the horizontal, each corresponding to a successive year of life, and stop at the parabolic line, represent the relative proportion of stature from year to year; while the parabola which unites the extremities of such lines may be regarded as a line drawn tangent to the top of the head of an individual through the successive periods of his life.
If we analyse this table, we find that the greatest increase in stature takes place during the first year; in fact, a child which at birth has an average length of body of 0.50 m. for males, and 0.48 m. for females (the new-born child does not have stature, but only length of body, since it has not yet acquired an erect position) has by the end of the first year augmented the length of body by 20 centimetres, which gives an average length of 0.70 m. In no other year of life will the stature acquire so notable an increase; it is very important for mothers to watch the growth of the child during this first year of its life; and the following figures may be useful for comparison:
It will be seen that the maximum increase takes place during the first four months—especially in the first month (4 cm. = 1.57 in.) the rate diminishing from this point up to the fourth month (2 cm. = 0.78 in.), after which the monthly increase remains steadily at one centimetre (0.39 in.).
Fig. 22.—New-born child, seen from in front and from behind. (Stratz.)
1 year. 8 months. 4 months. at birth.
Fig. 23—Skeleton of a child from birth to the age of one year.
GROWTH IN LENGTH OF BODY DURING THE FIRST YEAR OF LIFE
(From Figueira)
| Age in months | Length of body in metres | Monthly increase |
|---|---|---|
| 0 | 0.50 | 0 |
| 1 | 0.54 | 4 |
| 2 | 0.57 | 3 |
| 3 | 0.60 | 3 |
| 4 | 0.62 | 2 |
| 5 | 0.63 | 1 |
| 6 | 0.64 | 1 |
| 7 | 0.65 | 1 |
| 8 | 0.66 | 1 |
| 9 | 0.67 | 1 |
| 10 | 0.68 | 1 |
| 11 | 0.69 | 1 |
| 12 | 0.70 | 1 |
The same facts appear from the combination picture given by Stratz, showing an infant's skeleton at four-month intervals from birth to the end of the first year.
During the second year of life, the increase in stature is about one-half that of the preceding year, that is, about 10 cm. (4 in.), so that at the end of the second year the child attains a height of about 80 cm. (31½ in.). After this, the annual increase diminishes in intensity (see "Figures of the increase of stature according to Quétélet and other authors," in the technical part, Chapter VII), as is shown by the horizontal dotted lines, which, starting from a vertical line at points corresponding to the height of various statures, represent by the intervals of space between them the successive growth from year to year.
This increase is not regular, but proceeds by periodic impulses that in early childhood seem to recur at intervals of three years.
Thus for example the increase
- between 0- 3 years of age is successively 20, 10, 6 cm.
- between 3- 6 years of age is successively 7, 6, 5 cm.
- between 6- 9 years of age is successively 7, 6, 5 cm.
- between 9-12 years of age is successively 6, 4, 3 cm.
Accordingly we have a triennial rhythm, decreasing throughout the whole period of childhood; the maximum increase is in the first triennium, the second and third periods of three years correspond exactly, while the last period shows a lowered rate of increase.
At this point the period of approaching puberty begins (13 years for boys), after which the rate of increase becomes more rapid than it had been during the second or third period, attaining its maximum during the years 13-15; to be specific, the rate from 13 to 18 is successively 4, 8, 7, 5, 6, 3 cm.
When the period of puberty is ended (18 years), the rate of growth is much slower; in fact, during the two following years (18 to 20) it hardly attains one centimetre.
Nevertheless, the stature continues to increase up to the twenty-fifth year; according to Quétélet's figures, the average male stature at the age of eighteen is 1.70 m. (in Belgium) and at twenty-one it is 1.72 m.
From twenty-five to thirty-five the stature remains stable; this is the adult age, the full attainment of maturity; at the age of forty the period of involution insensibly begins, and after fifty in the case of women, and sixty in the case of men, the stature begins insensibly to decrease; a decrease which becomes more marked with the advance of age, corresponding to an anatomical diminution of the soft parts interposed between the bones in the sum of parts that make up the stature; more especially the intervertebral disks; and in connection with this phenomenon the vertebral column tends to become more curved.
According to Quétélet's figures, at the age of eighty the average male stature is 1.61 m. (5 ft. 3-2/5 in.), a stature corresponding to that of the age of sixteen.
Accordingly, the variations in stature throughout the different periods of life are neither a growth nor an evolution, but a parabolic curve, including evolution and involution. This curve represents the true human stature; the measurements taken successively from year to year representing nothing more than transitory episodes in the individual life.
Man, as he really is, we may represent by portraits taken successively from time to time, from his birth until his death; the occasional photograph which it is the custom to have taken represents nothing; following no rule, it seizes a fugitive instant in the life of an individual, who is never a fixed quantity but is constantly in transition during the whole course of his existence. So that the habit of taking a picture annually on a child's birthday is an excellent one if we wish to preserve a true likeness; and this practice is recommended in pedagogic anthropology, when it is desired to preserve the biographic history of the pupil.
It is interesting to study, side by side with the growth of stature and the marked rhythms and periods that constitute its laws, the phenomenon of general mortality in its relation to age.
Lexis gives the following curve of general mortality: the horizontal line marks the years and the vertical line the corresponding number of deaths, while the curved line shows the progress of mortality, and the highest points in the curve indicate the maximum mortality. It is highest of all during the first year and in general during early childhood, and is steadily lowered to a point corresponding to the ages from ten to thirteen, after which it rises again.
Fig. 24.—Curve of general mortality (Lexis).
Let us examine the curve up to this point, since it has a bearing upon our school work. We can prove that the maximum mortality corresponds to the maximum individual growth; in other words, an organism in rapid evolution is exposed to death, its powers of immunity to infective diseases are weakened; it constitutes what in medical parlance is known as a locus minoris resistentiæ.
In that period of calm in growth, which would seem to be a repose preceding the evolution of puberty, mortality is at the lowest; only to rise again rapidly during the period of puberty; while the rise becomes less rapid after the eighteenth year, notwithstanding that after that age mankind in general are exposed, in their struggle for existence, to many causes of death that did not exist during the preceding years. Toward the age of seventy the line of mortality attains another apex, because the age of normal death is reached; after which it drops precipitously because of the lack of survivors.
From these facts we may deduce certain very important principles that throw useful light upon pedagogy: there are certain ages at which even the strong are weak; and their weakness is of such a nature that it exposes the individual to death.
Now, whenever the phenomenon of mortality occurs it is always an indication of impoverishment in the survivors. For example, of every one person that dies, many persons have been ill who have recovered from their illness; but there are still many others who, although they did not actually fall ill, were weakened even though they passed through the peril unharmed.
In short, for each death, which represents a final disaster, there are many victims. And whenever there is a rise in the phenomenon of mortality in connection with any one age, it is our duty to give special attention to those individuals who are not only weak in themselves, but whom the social causes affecting them tend to weaken still more and push onward toward illness and death. Whenever there are many deaths, there are undoubtedly also many sufferers.
Now, in pedagogy we have no criterion to guide us in this matter of respecting the weaknesses characteristic of the various ages, as, for example, that of early infancy and of the age of puberty.
With the most cruel blindness we punish and discourage the lad who, having reached the age of puberty, no longer makes the progress in his studies that rendered him the brilliant champion during the period of physiological repose in his growth; and instead of regarding this as a psychic indication of a great physiological transformation that it is necessary to protect, we urge on the organism to enforced effort, without even suspecting that, in proportion to the degree of resistance of our pupil, we may be doing our share to induce in him a permanent weakness, or an arrest of development, or disease and death.
Our responsibility as educators is great, because we have the threads of life entrusted to our care; man represents a continuous transition through successive forms, and each following period has been prepared for by the one preceding.
Whenever we have the misfortune to concur in weakening a child, we touch that parabolic line traced in the graphic chart of stature, and standing as an index of the life of the body, and we give it a shock throughout its whole length; it may either be shattered or be brought down to a lower grade.
But the life of an individual does not contain merely that individual alone; the cycle of the stature with its violent period of puberty and the perfect physiological repose corresponding to the years from 25 to 36, or even 45, indicates the eternity of the individual in the species: his maturity for reproduction. Man in his progress through the different levels of height, as indicated on the graphic chart of stature, does not pass through them without reproducing himself, save in exceptional cases; he commences the ascent alone, but in his descent he attains the majesty of a creator who leaves behind him the immortal works of his own creation. Well, even the capacity of normal reproduction, and of begetting a strong species, is related to the normal cycle of life: whoever weakens a child and puts a strain upon the threads of its existence, starts a vibration that will be felt throughout posterity.
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.