When economists think of joining their subject with biology, it is Alfred Marshall who springs to mind for his celebrated remark that “the Mecca of the economist is economic biology rather than economic dynamics” (Pigou 1925, 318). His endorsement of the same motto as Darwin regarding nature's inability to take leaps has also been taken to suggest that Marshall was profoundly influenced by Darwin (see Niman 1991). It is certainly very tempting, and quite easy, to tell the following story. Darwin's Origin of Species (1859) propelled biology into a respectable scientific field such that economists could then turn to it to emulate, in place of physics. More specifically, Darwin's insights greatly reinforced long-standing appeals by economists to competition, equilibrating mechanisms, and historical explanation. Most of all, his thoroughgoing materialism transformed our conception of human psychology and morality. Both were products of our evolutionary history and thus at bottom just refined instincts. Economists could discard, once and for all, appeals to a human nature designed by the deity.

I will challenge this view. More specifically, I will show that there is little evidence that Darwinian biology shaped the content or even the broader context of early neoclassical economics, particularly as represented by Marshall. In doing this, I do not wish to suggest that economic theory and the theory of evolution have nothing in common. On the contrary, biological and economic reasoning have been closely intertwined since the Enlightenment. But there is probably as much Linnaeus in Adam Smith as Darwin in Marshall.