The Sense of Smell in Animals

Abstract

THE hypothesis put forward by Mr. Wallace in NATURE of the 20th ult., to explain the power possessed by some animals of finding their way back to their homes after having been conveyed from them in such a way as to preclude the possibility of their seeing the road by which they travelled, contains, I think, the solution of a hitherto perplexing problem. To ascribe this power, as is usual, to instinct in the customary sense of the term, is to give what Mr. Bain calls “an illusory explanation of repeating the fact in different language,” and it is manifestly impossible to ascribe it to instinct, as that term is understood in the evolution theory of mind. I am glad to see a psychologist like Prof. Robertson giving in his adhesion to Mr. Wallace's view. But while in the main accepting it, and arguing forcibly in its favour, Prof Robertson hesitates to affirm that it affords an explanation of the whole of the facts in question. Is this failure, if failure there be, inherent in the explanation itself, or does it lie in our imperfect knowledge of the facts to be explained? That there are difficulties cannot be denied. For example, it is difficult, to say the least, for the human mind to form the conception of a sense of smell, so acute, so objective, and furnishing sensations so strongly persistent in the ideal, as to enable an animal by its means alone, to retrace unerringly long and devious roads travelled over but once, and under circumstances rendering impossible the co-ordination of sights and smells habitual to the animal. In such cases smell must be a much closer second, if second at all, to sight, than touch is in man. No blindfolded man could perform a like feat by means of unaided touch, nor, do I think, could a blind man, though with the blind this sense becomes, by the cultivation it receives through a hard necessity, greatly more acute than it is in normal cases. But difficulties like these are such, I believe, only because of our very limited acquaintance with the psychology of the lower animals. One of the chief desiderata in mental science is, it seems to me, such a psychology, based upon principles generalised according to strict inductive methods, from a body of numerous, varied, well-authenticated, and scientifically made observations of the domestic and other animals. A work of this kind we have not, but, I believe, the lines upon which it should be constructed are already laid down in Mr. Spencer's truly great work, the “Principles of Psychology.” When this branch of psychological science has been brought into something like parallelism with human psychology, difficulties, such as I have hinted at, will, I venture to say, be effectually removed, and Mr. Wallace's explanation will, as he claims for it, “cover all the well-authenticated cases of this kind.”