Logo IMG


1798: Darwin and Malthus

Keith Thomson

The Limits of Improvement

Malthus had been explicit, however, in denying a cornerstone of Darwin's ideas, namely that artificial selection is a model for change in nature. The passage is worth quoting: "I am told that it is a maxim among the improvers of cattle that you may breed to any degree of nicety you please, and they found this maxim on another, which is that some of the offspring will possess the desirable qualities of the parents in a greater degree … the point of improvement … may be said to be undefined but this is very different from unlimited or indefinite…."

Darwin had read this familiar complaint many times before, most forcefully in Lyell's second volume. Darwin's special genius was to see in Malthus's pessimistic principles the seeds of change, after all. Once variation is granted, the engine of evolution lay in the struggle inevitably caused by confrontation of superfecundity and resource limitations, precisely because it forced choices—selection is, therefore, natural.

It is an amusing [sic] exercise to try to find specific wording in Malthus that might have triggered Darwin's ideas. For example, he refers explicitly to contests between tribes as a "struggle for existence." And one might imagine that Darwin turned upside down Malthus's metaphor of seed germination: "The powers of selection, combination, and transmutation [emphasis added], which every seed shews, are truly miraculous … they chuse, amongst all the dirt and moisture that [surround] them, those parts which best [suit] their purpose…." Perhaps Darwin, typically contrarian, found inspiration in the glaring paradox of Malthus's argumentation about human societies. He is at pains to show that population pressure keeps most societies in a subsistence state, but does not explore fully what factors must have worked to allow others (including turn-of-the-century Britain) to flourish and develop.

It is highly unlikely that Malthus would have been persuaded to the evolutionists's side, had he lived. He would certainly have dismissed Chambers's progressivist Vestiges of the Natural History of Creation (1844). In fact, Malthus suited Darwin perfectly in his denial of the notions of steady inevitable progress and improvement toward "perfection" in humans, animals and plants so favored, respectively, by social thinkers like Condorcet and transmutationists like Lamarck and Chambers.

How crucial then was Malthus? One could argue ("for amusement") that if Darwin had not read Malthus, some other event would have triggered his idea of a mechanism for natural selection. He might instead, for example, have read Paley again. Similarly, we know for a fact that if Darwin had not published his ideas on natural selection, someone else would have (Wallace did). We cannot be sure that if Malthus had not been stung into action by Godwin's excesses, The Essay would have remained unwritten. Failing Malthus, someone else might have formulated the population principle powerfully and concisely. Other writers than Godwin popularized Condorcet in English. And so on. The fact remains that Malthus, for all his shortcomings as a social theorist, formulated a principle of population growth that no one has been able to falsify and that forms a foundation stone of the theory of evolution by natural selection.

As for theories of poverty and labor, the last word can be left to Marx (Groucho, not Karl): "Well, what makes wage slaves? Wages!" (Cocoanuts).

© Keith Thomson

comments powered by Disqus


Subscribe to American Scientist