Russel Wallace : Alfred Russell Wallace (sic)
Sir--I quite agree with Dr. Greville Macdonald in his rejection of Metchnikoff's theory of the possible immortality of man’s body, but I am rather surprised that, as an evolutionist, he did not found his objections on a more scientific basis.
It appears to me to be almost self-evident that the death of individuals is absolutely essential for the development and multiplication of species, and therefore for the production of any of the higher forms of life. Any other state of things is unthinkable, with evolution as it is and has been. It operates only by rapid multiplication and continuous variation, with the resultant survival of the fittest. If at any time during the vast eons of evolution from the lower marine forms up to terrestrial animals and man the existing species had become potentially immortal, the result would really have been the extinction of the greater portion of them--perhaps of all! For the excessively rapid increase of the vegetable feeders would soon have destroyed all vegetation, and they would necessarily have died of hunger. Then the carnivora would have had to feed on each other, and only the most powerful would survive, when they too must feed on their own kind, and at last become extinct. Potential immortality--that is, the power of surviving all adverse conditions but those which actually disintegrate the body--would entirely put a stop to evolution.
Weismann has also shown (as I had done myself) that the duration of life in each species has been established by natural selection, being that which just secures the continuance of the race, anything more than that being injurious.
The idea that a quality or condition of organized life, which has been throughout essential for evolution, should now, in the case of our species, be possibly changed to its direct opposite, seems to me the wildest and most unscientific I have ever heard from a man of science. So soon as it came into operation population would rapidly increase, and in a very few generations the earth would become so crowded that either wholesale infanticide must be practised or the instinct of reproduction be abolished.
If life (for some) is not worth living now, what would it be then?--Yours, &c.,
Alfrec R. Wallace,