Shadows of Forgotten Ancestors

  “Wild cats are prolific and have few enemies; why then are they never as abundant as rabbits? The only intelligible answer is, that their supply of food is more precarious. It appears evident, therefore, that so long as a country remains physically unchanged, the numbers of its animal population cannot materially increase. If one species does so, some others requiring the same kind of food must diminish in proportion. The numbers that die annually must be immense; and as the individual existence of each animal depends upon itself, those that die must be the weakest—the very young, the aged, and the diseased,—while those that prolong their existence can only be the most perfect in health and vigour—those who are best able to obtain food regularly, and avoid their numerous enemies. It is, as we commenced by remarking, ‘a struggle for existence,’ in which the weakest and least perfectly organized must always succumb …” (Alfred Russel Wallace, “On the Tendency of Varieties to Depart Indefinitely from the Original Type” [Wallace’s contribution to Darwin and Wallace, “On the Tendency of Species to Form Varieties; and on the Perpetuation of Varieties and Species by Natural Means of Selection”], in Journal of the Proceedings of the Linnean Society: Zoology

, Volume III [London: Longman, Brown, Green, Longmans & Roberts, and Williams and Norgate, 1859], pp. 56, 57.)24. In subsequent editions, the sentence was amended to read “Much light will be thrown on the origin of man and his history” (our emphasis).

Chapter 4

A GOSPEL OF DIRT