Page:George Archdall Reid 1896 The present evolution of man.djvu/123

Rh move them are also enlarged, nothing will be gained. Such modification of the neck will be useless, or rather will be detrimental, if its fulcrum be not made capable of resisting intense strains; the upper dorsal vertebræ and their spines must be strengthened, that they may withstand the more violent contraction of the neck muscles; and like changes must be made on the scapular arch; still more must there be required a simultaneous development of the bones and muscles of the fore-legs," &c .—Principles of Biology, vol. i.

Such, as briefly but as fairly as I am able to give them, are Mr. Spencer's arguments. They are set forth at great length in the pamphlet we have under consideration, and in his book, the Principles of Biology, from which the quotation given above is taken. Examined closely, we find that they are nearly the same arguments, but much amplified, as those already dealt with, whereby he sought to prove that accumulation of inborn variations is not alone sufficient to account for the evolution of any given quality (e.g. sight, scent, hearing, speed, &c., each of which depends on the functional activity of a group of structures), on the ground that if one animal survived because of superior keenness of sight, and others survived because of superior powers of scent, or hearing, or speed, or agility, or digestion respectively, then, since the qualities essential to survival are numerous, the several superiorities would be cancelled by interbreeding, and in the end there would be no evolution. He forgot, as we saw, that the essential qualities are not found disassociated, keenness of sight in one deer, keenness of hearing in another, and so forth; and moreover, that excellence in one quality is not unusually accompanied by excellence in other qualities, the vigorous in one respect being usually vigorous in other respects as well.