In 1846, Karl Marx and Friedrich Engels wrote The German Ideology, the first mature statement of what became known as historical materialism.  This passage was on the second page:

We know only a single science, the science of history.  One can look at history from two sides and divide it into the history of nature and the history of men.  The two sides are, however, inseparable; the history of nature and the history of men are dependent on each other so long as men exist.  The history of nature, called natural science, does not concern us here. . . . .

At the last minute, they deleted that paragraph from the final draft, deciding not even to mention a subject they had no time to investigate and discuss properly.

What the founders of scientific socialism couldn't have known was that a compelling materialist explanation of the history of nature had already been written by an English gentleman who had no sympathy for socialism.  They couldn't read that account, because the author, Charles Darwin, was so shocked by the implications of his own ideas that he kept them secret for twenty years.

Darwin's views on evolution were fully developed by 1838, and he wrote, then hid away, a 50,000-word essay on the subject in 1844.  But he didn't publish what Marx was to call his "epoch-making work" until 1859.

Darwin's Insight

Others had speculated about evolution before Charles Darwin, but the dominant view in scientific circles and society at large was that all the different types of plants and animals were created by God, and that the various species were forever fixed.  The few who believed that species had changed over time couldn't explain those changes without resort to the supernatural -- that evolution was God's long-term plan, or that some force (God by another name) caused nature to strive towards perfection.

What made Darwin's work unique was not his assertion that evolution was a fact, but his entirely materialist explanation of how all of life's wonderful variations and designs had come to be.  He argued that the main factor in evolution is "natural selection," a process that can be summarized simply.

• All organisms produce more offspring than can possibly survive.

• There are many differences between the individual members of any species.

• Variations that increase individuals' chances of surviving to reproduce are likely to be passed on to the next generation.

• As a result, over long periods of time, such favorable characteristics will spread through the population, while harmful characteristics will decline, so the population as a whole will increasingly be better adapted to its environment.

• If part of the population finds itself in a different environment, it will change in different ways, and those diverging changes can eventually lead to the development of separate species.

This simple and elegant concept took the evidence most commonly used to defend creationism -- the seemingly perfect design of plants and animals -- and explained it by natural processes.  In the words of twentieth century evolutionist Ernst Mayr, Darwin "replaced theological, or supernatural, science with secular science. . . .  Darwin's explanation that all things have a natural cause made the belief in a creatively superior mind quite unnecessary."

Darwin's Delay

Darwin's theory was entirely materialist at a time when materialism wasn't just unpopular in respectable circles but considered subversive and politically dangerous.  Between 1838 and 1848, while he was working out his ideas, England was swept by an unprecedented wave of mass actions, political protests, and strikes.  Radical ideas --materialist, atheistic ideas -- were infecting the working class, leading many to expect (or fear) revolutionary change.

Darwin was never actively involved in politics, but he was a privileged member of the wealthy middle class, and that class was under attack.  As John Bellamy Foster writes, "Darwin was a strong believer in the bourgeois order.  His science was revolutionary, but Darwin was not."

Rather than risk being identified with the radicals, Darwin set evolution aside, and devoted the next years to writing a popular account of his voyage around the world, two scientific books on coral reefs and volcanic islands, and an exhaustive four-volume study of barnacles.  Only in the mid-1850s, when his scientific reputation was assured, and the social turbulence of the 1840s was clearly over, did he return to the subject he is now most famous for.

Even then he would likely have delayed into the next decade had not a younger naturalist, Alfred Russell Wallace, sent him an essay containing ideas virtually identical to his own, in June 1858.  Pressed by friends to publish first, Darwin set aside "the big book on species" he had barely begun, and quickly wrote a much shorter one -- On the Origin of Species by Means of Natural Selection, or, The Preservation of Favoured Races in the Struggle for Life.  It was published in November 1859.

Brilliantly argued, and written to be understood by non-scientists, Origin was an instant bestseller.  The publisher printed 1,250 copies but received orders for 1,500 copies on the first day.  A second edition of 3,000 copies followed in a few weeks, and four more editions in the next ten years: some 110,000 copies were sold in England alone by the end of the century.

While Darwin's ideas were quickly accepted by many scientists, especially younger ones, they were roundly condemned by the scientific establishment and by religious leaders.  Again and again the critics raised two related arguments: that natural selection excluded any role for God; and that although Darwin had cautiously avoided the subject, human beings must also be products of natural selection.  Both ideas were blasphemous; both would undermine the existing social order.

Even among scientists who rejected Biblical literalism and agreed with much of Darwin's argument, there were many who insisted that God had to be part of the explanation, as the guiding force of evolution or as the divine source of the human soul and intelligence.  Some used that view to defend their own reactionary and racist prejudices: for example, that God had created blacks and whites as separate species.

Working-Class Support

The discussion of Darwin's book wasn't limited to scientists and clergymen.  At fifteen shillings, several days' pay for a skilled craftsman, The Origin of Species was too expensive to be found in many workers' homes, but groups of radical workers in several cities took up collections to buy one copy that could be passed around.

One of Darwin's closest collaborators, Thomas Huxley, organized a series of very well attended public lectures on evolution for working men in London.  In those talks, which were subsequently published as a popular pamphlet, Huxley had no hesitation in defending a key point Darwin only hinted at in Origin, that humans too are a product of natural selection and share common ancestors:

there is no evidence whatever for saying that mankind sprang originally from any more than a single pair; I must say, that I cannot see any good ground whatever, or even any tenable sort of evidence, for believing that there is more than one species of Man.

Karl Marx attended several of Huxley's lectures and encouraged his political associates to do likewise.  His friend and comrade Wilhelm Liebknecht later recalled that "when Darwin drew the conclusions from his research work and brought them to the knowledge of the public, we spoke of nothing else for months but Darwin and the enormous significance of his scientific discoveries."

Friedrich Engels obtained one of the first 1,250 copies of The Origin of Species: he wrote to Marx that it was "absolutely splendid."   Marx agreed, but that did not mean that they were uncritical.  They disliked Darwin's "clumsy English style of argument" and ridiculed his positive references to Malthus.   Since they were not themselves biologists, they didn't take sides in the highly contentious debate on whether natural selection or some other natural process was the principal driver of evolution: in his strong defense of Darwin in Anti-Duhring (1877), Engels wrote, and Darwin would surely have agreed:

The theory of evolution itself is however still in a very early stage, and it therefore cannot be doubted that further research will greatly modify our present conceptions, including strictly Darwinian ones, of the process of the evolution of species.

What he and Marx most admired about Darwin was his demonstration that nature has a history.  Again in Socialism: Utopian and Scientific:

Nature works dialectically and not metaphysically . . . she does not move in the eternal oneness of a perpetually recurring circle, but goes through a real historical evolution.  In this connection, Darwin must be named before all others.  He dealt the metaphysical conception of Nature the heaviest blow by his proof that all organic beings, plants, animals, and man himself, are the products of a process of evolution going on through millions of years.

The insight that Marx and Engels had written and then deleted in 1846 -- that the history of nature and the history of men are inseparable and dependent on one another -- was confirmed by The Origin of Species.  In it they found a materialist explanation of nature's history to complement their materialist explanation of human history.  Darwin's work was, as Marx wrote in 1861, "the basis in natural history for our own view."

A Triumph for Humanity

It is a testimony to Darwin's commitment to scientific truth that, once he overcame his reluctance to publish his ideas, he devoted the rest of his life to defending them against some of the most influential opinion leaders of his day.  By the time he died in 1882, the fact of evolution was almost universally accepted in the scientific community.

Subsequent research has deepened our understanding of evolution -- it has also confirmed Darwin's conviction that natural selection plays a key role.  Above all, Darwin's commitment to materialist explanations of natural phenomena has triumphed.  No modern scientist, not even one with deep religious convictions, would suggest that "then a miracle happened" is an acceptable explanation for any natural phenomenon, including the origins, immense variety and constantly changing nature of life on our planet.

This materialist victory in science is one of humanity's greatest achievements.  For that reason alone, no matter what his hesitations, delays, or middle class prejudices, Charles Darwin deserves to be remembered and honored by everyone who looks forward to the ending of superstition and ignorance in all aspects of life.

The idea that "nature does not just exist, but comes into being and passes away" (Engels) is just as revolutionary, and just as important to socialist thought, as the idea that capitalism doesn't just exist, but came into being at a given time, and it too will pass away in the future.

Suggestions for Further Reading

• The best short overview of Darwin's life and ideas is A Brief Guide to Charles Darwin, His Life and Times, by Cyril Aydon (Constable & Robinson, 2002).
• Chapter Six of John Bellamy Foster's Marx's Ecology: Materialism and Nature (Monthly Review 2000) is essential reading on the relationship between Marxism and Darwinism.
• John Bellamy Foster's latest book, Critique of Intelligent Design: Materialism versus Creationism from Antiquity to the Present, was not yet available when I wrote this article, but having read his previous works, I have no hesitation in recommending it.
• Ernst Mayr's What Evolution Is (Basic Books, 2001) isn't light reading, but it is a superb presentation of modern evolutionary theory for non-scientists.
• Finally, Charles Darwin's The Origin of Species may be the only great work of science that is also a work of literature.  The Penguin edition includes a good introduction by historian J.W. Burrow and is widely available.