Page:Popular Science Monthly Volume 67.djvu/64

58 existence, is extremely wasteful, and far from being as perfect as we can easily imagine it might become if the process could be regulated by individual selection.

Are organisms ever more perfectly adapted in certain characters to their environment than the demands of survival require? A positive answer to this question might release us in part from the modern test of utilitarianism.

It is a well-known fact that through use many, perhaps all, parts of the body are capable of doing more than they are called upon to do during the ordinary life of the individual. The muscles through practise not only become larger and stronger, but can even be educated to do more rapid work, as seen in the fingers of the skilled pianist. The sensation of touch can be made more perfect through practise. The skin thickens wherever continued pressure is brought to bear on it. The bones will change their form, and even make new sockets under suitable conditions. The walls of the blood vessels become thicker if more blood is thrown into the blood channels. These are typical examples of what the body is capable of doing, and the responses in each case are obviously to the advantage of the individual. What is the meaning of this power to do more than the ordinary requirements of life demand?

It has been suggested that the survival of the individual is sometimes determined by its capacity to rise to extreme occasions. For example, the deer that is capable of putting on a little more speed than its fellows, is the one that escapes. But this assumption fails to meet fully the case, for, in the first place, it assumes as already present a certain amount of the very quality to be explained. In the second place a similar capacity is also present in other organs, in which it is highly improbable that the power to improve somewhat could be of sufficient importance to be decisive in a life and death struggle. It could be of little advantage for instance to have the power of improving the musical sense beyond a very low average, and no one will suppose that this has been decisive in the evolution of the race.

In other directions also we find an apparently superfluous perfection of development. It is improbable that the extraordinary adjustments of which the eye is capable have all been acquired little by little through a life and death struggle. The eye is, however, such an important organ for the welfare of the individual, that it is hard to demonstrate positively that each stage was not of great use, but for the ear it seems improbable that its perfection in certain respects could have been of vital importance for the maintenance of the race.

The symmetry of animals and of plants is also in many cases