Wallace's Conundrum

By Ann Gauger

The co-discoverer of the theory of evolution by natural selection, Alfred Russel Wallace, didn’t think human evolution could be explained solely in terms of Darwinian processes, at least as far as human cognition and behavior was concerned. And it cost him his scientific reputation.

Varki, Geschwind and Eichler [1] summarize it this way:

Wallace lost favour with the scientific community partly because he questioned whether natural selection alone could account for the evolution of human mind, writing: “I do not consider that all nature can be explained on the principles of which I am so ardent an advocate; and that I am now myself going to state objections, and to place limits, to the power of ‘natural selection’. How could ‘natural selection’, or survival of the fittest in the struggle for existence, at all favour the development of mental powers so entirely removed from the material necessities of savage men, and which even now, with our comparatively high civilization, are, in their farthest developments, in advance of the age, and appear to have relation rather to the future of the race than to its actual status?”

Although Wallace was criticized for apparently invoking spiritual explanations, one of his key points remains valid — that it is difficult to explain how conventional natural selection could have selected ahead of time for the remarkable capabilities of the human mind, which we are still continuing to explore today. An example is writing, which was invented long after the human mind evolved and continues to be modified and utilized in myriad ways. Explanations based on exaptation seem inadequate, as most of what the human mind routinely does today did not even exist at the time it was originally evolving. Experts in human evolution or cognition have yet to provide a truly satisfactory explanation. Thus, ‘Wallace’s Conundrum’ remains unresolved: “[…] that the same law which appears to have sufficed for the development of animals, has been alone the cause of man’s superior mental nature, […] will, I have no doubt, be overruled and explained away. But I venture to think they will nevertheless maintain their ground, and that they can only be met by the discovery of new facts or new laws, of a nature very different from any yet known to us.” [2]

1. doi:10.1038/nrg2428

2. Internal citations have been removed for clarity, and emphasis added. The quotations from Wallace are taken from Wallace, AR (1870) Contributions to the Theory of Natural Selection. A Series of Essays (Macmillan, London).