James Mark Baldwin (1861-1934) Mental Development in the Child and the Race (1897)
Chapter 1: Infant and Race Psychology
4. Variations in Ontogeny
...In this matter of the interpretation of the whole infancy period, including both prenatal and postnatal infancy, however, there seem to be two influences at work which tend to opposite results. We have seen that abundant food supply in the conditions of embryonic or prenatal life tends to swift development and developmental abbreviation. The newborn animal is soon fitted, under these conditions, for independent life on a comparatively high level of competition. This shortness of the embryonic period seems to be in direct relation to the shortness or entire absence of the postnatal infancy period. Being thus fitted to take care of himself by advanced uterine development, he does not need after birth the artificial care, protection, etc., of other infants.
On the other hand, where we find a long postnatal infancy period, as in the case of the child, we find also a long antecedent embryo period, in spite of the abundant food supply afforded by the placental method of uterine nourishment.
The difference in the two cases seems to find some explanation when we look at the nature of the mental endowment secured in each case respectively. In the former case -- that of swift intra-uterine preparation for immediate, independent life -- the goal is refined and varied instinct, a matter of organic structure secured by earlier phylogenetic development: so the pathway of progress is already well trodden and the young organism has a straight road to grow along, marked out by its hereditary impulse. So the stretch to maturity is made rapidly.
In the case, however, of long infancy, both before and after birth, the mental gifts to be secured are of a kind not already crystallized in instinct. The hereditary impulses require a long ontogenetic evolution in each individual. So in spite of all the favourable conditions of abundant food, freedom from disturbing influences, etc., the creature must have both one and the other period at its longest.
The psychological considerations -- which I am careful to keep to, not making any claim to biological expertness -- would seem to favour some such formulation as the following: the extra-uterine infancy period is to the intra-uterine embryonic period, the conditions being equally favourable, as the amount of possible ontogenetic development is to the amount of phylogenetic development, in the entire working out of the creature's hereditary impulse. For although with creatures of instinct, which represent much phylogeny, the sum of the two periods is short, still the prenatal infancy period is relatively long, while with creatures of intelligence, which represent much ontogeny, although their whole period is long, yet the prenatal infancy period is relatively short.
4. Variations in Ontogeny
...In this matter of the interpretation of the whole infancy period, including both prenatal and postnatal infancy, however, there seem to be two influences at work which tend to opposite results. We have seen that abundant food supply in the conditions of embryonic or prenatal life tends to swift development and developmental abbreviation. The newborn animal is soon fitted, under these conditions, for independent life on a comparatively high level of competition. This shortness of the embryonic period seems to be in direct relation to the shortness or entire absence of the postnatal infancy period. Being thus fitted to take care of himself by advanced uterine development, he does not need after birth the artificial care, protection, etc., of other infants.
On the other hand, where we find a long postnatal infancy period, as in the case of the child, we find also a long antecedent embryo period, in spite of the abundant food supply afforded by the placental method of uterine nourishment.
The difference in the two cases seems to find some explanation when we look at the nature of the mental endowment secured in each case respectively. In the former case -- that of swift intra-uterine preparation for immediate, independent life -- the goal is refined and varied instinct, a matter of organic structure secured by earlier phylogenetic development: so the pathway of progress is already well trodden and the young organism has a straight road to grow along, marked out by its hereditary impulse. So the stretch to maturity is made rapidly.
In the case, however, of long infancy, both before and after birth, the mental gifts to be secured are of a kind not already crystallized in instinct. The hereditary impulses require a long ontogenetic evolution in each individual. So in spite of all the favourable conditions of abundant food, freedom from disturbing influences, etc., the creature must have both one and the other period at its longest.
The psychological considerations -- which I am careful to keep to, not making any claim to biological expertness -- would seem to favour some such formulation as the following: the extra-uterine infancy period is to the intra-uterine embryonic period, the conditions being equally favourable, as the amount of possible ontogenetic development is to the amount of phylogenetic development, in the entire working out of the creature's hereditary impulse. For although with creatures of instinct, which represent much phylogeny, the sum of the two periods is short, still the prenatal infancy period is relatively long, while with creatures of intelligence, which represent much ontogeny, although their whole period is long, yet the prenatal infancy period is relatively short.