Wallace’s Essay has been reprinted without any alteration in his “Essays on Natural Selection,” recently re-issued combined with “Tropical Nature.”
CHAPTER XI.
COMPARISON OF DARWIN’S AND WALLACE’S SECTIONS OF THE JOINT MEMOIR—RECEPTION OF THEIR VIEWS—THEIR FRIENDSHIP.
WALLACE AND DARWIN.
Comparing the essays of these two naturalists, we observe that Darwin here first makes public the phrase “natural selection,” Wallace the “struggle for existence”; although so closely do their lines of thought converge that Darwin, using practically the same words, speaks of the “struggle for life.” Both show, by examples, the tendency of all animals to multiply at an enormous rate, and both show that their tolerably constant numbers are due to the constant supply of food.
Both treat of domesticated animals, but in very different ways. Darwin uses them as the practical illustration of selection, and argues that if man by selection can make such forms, Nature can make her species by the same means. Wallace disposes of the argument that the reversion of domesticated varieties to the wild form is a proof of the permanent distinctness of species, by showing in some detail that the former are “abnormal, irregular, artificial.”
Neither of them draws any distinction between instinct and other qualities, but assumes that the former is, like the latter, operated upon by natural selection.
Wallace makes a special point of protective resemblances in the colours of insects, etc.
The important principle of “divergence of character,” and the relatively unimportant one of “sexual selection,” are both clearly explained by Darwin.
Neither writer speaks of the direct effect of external conditions—except as a cause of plasticity by Darwin—or the inherited effects of use and disuse. Lamarck is mentioned only to be dismissed by Wallace. The evolution of the giraffe’s long neck is explained by Wallace on the principle of natural selection, which is contrasted with Lamarck’s original explanation of the same character. This contrast, which has been so often drawn, was therefore originally contained in the first public statement of natural selection.