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are similar, it is likely that they were selected for their utility in the comprehension of speech (J.D. Clark et al., 2003). And the human ASPM gene, which when mutated causes microcephaly and lowered intelligence, also shows signs of selection in the generations since our common ancestor with chimpanzees (Evans et al., 2004b). It is likely that many more genes with cognitive, social, and linguistic effects will be identified in the coming years, and the theory of the cognitive niche predicts that most or all will turn out to be adaptively evolved.


Even if the evolution of powerful language and intelligence were explicable by the theory of the cognitive niche, one could ask, with Wallace, how cognitive mechanisms that were selected for physical and social reasoning could have enabled H. sapiens to engage in the highly abstract reasoning required in modern science, philosophy, government, commerce, and law.

A key part of the answer is that, in fact, humans do not readily engage in these forms of reasoning (Pinker, 1997, 2002, 2007). In most times, places, and stages of development, people’s abilities in arithmetic consist of the exact quantities “one,” “two,” and “many,” and an ability to estimate larger amounts approximately (Carey, 2009). Their intuitive physics corresponds to the medieval theory of impetus rather than to Newtonian mechanics (to say nothing of relativity or quantum theory) (McCloskey, 1983). Their intuitive biology consists of creationism, not evolution, of essentialism, not population genetics, and of vitalism, not mechanistic physiology (Atran, 1998). Their intuitive psychology is mind-body dualism, not neurobiological reductionism (Bloom, 2003). Their political philosophy is based on kin, clan, tribe, and vendetta, not on the theory of the social contract (Daly and Wilson, 1988). Their economics is based on tit-for-tat back-scratching and barter, not on money, interest, rent, and profit (Fiske, 2004). And their morality is a mixture of intuitions of purity, authority, loyalty, conformity, and reciprocity, not the generalized notions of fairness and justice that we identify with moral reasoning (Haidt, 2002).

Nonetheless, some humans were able to invent the different components of modern knowledge, and all are capable of learning them. So we still need an explanation of how our cognitive mechanisms are capable of embracing this abstract reasoning.

The key may lie in a psycholinguistic phenomenon that may be called metaphorical abstraction (Jackendoff, 1978; Lakoff and Johnson, 1980; Talmy, 2000; Pinker, 2007). Linguists such as Ray Jackendoff, George Lakoff, and Len Talmy have long noticed that constructions associated with concrete

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