subject matter, and combine them productively. These abilities can help explain the emergence of abstract cognition without supernatural or exotic evolutionary forces and are in principle testable by analyses of statistical signs of selection in the human genome.
The bicentennial of Darwin’s birth and sesquicentennial of the publication of the Origin of Species have focused the world’s attention on the breathtaking scope of the theory of natural selection, not least its application to the human mind. “Psychology will be based on a new foundation,” Darwin famously wrote at the end of the Origin, “that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history.”
Far less attention has been given to the codiscoverer of natural selection, Alfred Russel Wallace, despite his prodigious scientific genius, and it is unlikely that the bicentennial of his birth in 1823 will generate the same hoopla. One reason was that Wallace turned out to be less prescient about the power of natural selection as an explanation of adaptive complexity in the living world. In particular, Wallace notoriously claimed that the theory of evolution by natural selection was inadequate to explain human intelligence:
Our law, our government, and our science continually require us to reason through a variety of complicated phenomena to the expected result. Even our games, such as chess, compel us to exercise all these faculties in a remarkable degree…. A brain slightly larger than that of the gorilla would … fully have sufficed for the limited mental development of the savage; and we must therefore admit that the large brain he actually possesses could never have been solely developed by any of those laws of evolution, whose essence is, that they lead to a degree of organization exactly proportionate to the wants of each species, never beyond those wants….
Natural selection could only have endowed savage man with a brain a few degrees superior to that of an ape, whereas he actually possesses one very little inferior to that of a philosopher.
Wallace (1870b, pp. 340, 343)
The upshot, claimed Wallace, was that “a superior intelligence has guided the development of man in a definite direction, and for a special purpose” (1870b, p. 359).
Few scientists today accept Wallace’s creationism, teleology, or spiritualism. Nonetheless it is appropriate to engage the profound puzzle he raised; namely, why do humans have the ability to pursue abstract intel-