The Story of the Mind

by James Mark Baldwin

This seems reasonable, for we do find that actions which were at first intelligent may be performed so frequently that we come to do them without thinking of them; to do them from habit. So the animals, we are told, have come to do theirs reflexly, although at first they required intelligence. From this point of view—that although intelligence was at first required, yet the actions have become instinctive and lacking in intelligent direction in later generations—this is called the theory of Lapsed Intelligence.

This theory has much to commend it. It certainly meets the objection to the reflex theory which was stated just above—the objection that some of the instincts could not have arisen by gradual reflex adaptations. It also accounts for the extremely intelligent appearance which many instincts have.

But this view in turn is liable to a criticism which has grown in force with the progress of biological knowledge in recent years. This criticism is based on the fact that the theory of lapsed intelligence demands that the actions which the animals of one generation have acquired by their intelligence should be handed down through heredity to the next generation, and so on. It is evident that unless this be true it does no good to the species for one generation to do things intelligently, seeing that if the effects on the nervous system are not transmitted to their children, then the next and later generations will have to start exactly where their fathers did, and the actions in question will never become ingrained in the nervous system at all.

Now, the force of this criticism is overwhelming to those who believe—as the great majority of biologists now do[1]—that none of the modifications or so-called "characters" acquired by the parents, none of the effects of use or disuse of their limbs, none of the tendencies or habits of action, in short, none of the changes wrought in body or mind of the parents during their lifetime, are inherited by their children. The only sorts of modification which show themselves in subsequent generations are the deep-seated effects of disease, poison, starvation, and other causes which concern the system as a whole, but which show no tendency to reproduce by heredity any of the special actions or functions which the fathers and mothers may have learned and practised. If this difficulty could be met, the theory that intelligence has been at work in the origination of the complex instincts would be altogether the preferable one of the two; but if not, then the "lapsed intelligence" view must be thrown overboard.

[1] The matter is still under discussion, however, and I do not mean in any way to deny the authority of those who still accept the "inheritance of acquired characters."

Recent discussion of evolution has brought out a point of view under the name of Organic Selection which has a very fruitful application to this controversy over the origin of instincts. This point of view is one which in a measure reconciles the two theories. It claims that it is possible for the intelligent adaptations, or any sort of "accommodations," made by the individuals of one generation, to set the direction of subsequent evolution, even though there be no direct inheritance of acquired characters from father to son. It proceeds in the case of instinct somewhat thus:

Suppose we say, with the first theory given above, that the organism has certain reflexes which show some degree of adaptation to the environment; then suppose we admit the point, urged by the advocates of the lapsed intelligence theory, that the gradual improvement of these reflexes by variations in the endowment of successive generations would not suffice for the origin of instinct, seeing that partial instincts would not be useful; and, further, suppose we agree that many of the complex instincts really involved intelligent adaptation in their acquisition. These points carefully understood, then one new and further principle will enable us to complete a theory which will avoid the objections to both the others. This principle is nothing else than what we have seen already—namely, that the intelligence supplements the partial instincts in each generation and makes them useful in the respects in which they are inadequate, and so keeps the young alive in successive generations as long as the instinct is imperfect. This gives the species time gradually to supplement its instinctive endowment, in the course of many generations each of which uses its intelligence in the same way: time to accumulate, by the occurrence of variations among the offspring, the changes in the nervous system which the perfect instinct requires. Thus as time goes on the dependence of each generation upon the aid of intelligence is less and less, until the nervous system becomes capable of performing the function quite alone. The result then will be the same as if the acquisitions made by each generation had been inherited, while in reality they have not. All that this theory requires in addition to what is admitted by both the historical views is that the species be kept alive long enough by the aid of its intelligence, which supplements imperfect instincts, to give it time to produce sufficient variations in the right direction. The instinct then achieves its independence, and intelligent supervision of it is no longer necessary (see Fig. 1).

Fig. 1,—Origin of instinct by Organic Selection: A n, perfect instinct. 1, 2 ... n, successive generations. Solid lines, nervous equipment in the direction of the instinct. Dotted lines, intelligence supplementing the nervous equipment. The intelligence is relied upon to keep the species alive until by congenital variations the nervous equipment becomes "perfect."