ABOVE: Engraving of economist and clergyman Thomas Robert Malthus, probably by Amable Nicolas Fournier (image source). Darwin’s notion of natural selection was crucially inspired by Malthus’ work on human population.
So far we’ve examined Darwin’s family background and university education, leading up to his long internship on HMS Beagle. Now we get to the meat of the matter: his theory of evolution by natural selection, which was to a significant degree an idea shaped by ideas put forth by Thomas Malthus and Adam Smith, two giants of British economics. Basically, Darwin took ideas from the “economy of man” and applied them to the “economy of nature.” This is why some historians like to say that only a nineteenth-century Englishman could have come up with evolution by natural selection.
The Mystery of Mysteries
When the Beagle arrived back in England in Oct 1836, Darwin was not yet an evolutionist. Soon he moved to London, where he became involved in the Geological Society of London (the most active scientific group at the time) and befriended geologist Charles Lyell, the doyen of British natural history whose ideas about the great age of the Earth and the very gradual pace of geological change had been, and would remain, so influential on him.
At just this point, Darwin started compiling several notebooks devoted to the species question: how are species related to one another in time? What factors must be explained? We get a sense of his quandary from a line in a notebook devoted to transmutation (the word then used to mean what we now call “evolution”): “Herschel calls the appearance of new species the mystery of mysteries.” John Herschel, son of the great astronomer William Herschel, was a prominent philosopher, scientist, and mathematician. Darwin had visited him when the Beagle stopped at the Cape of Good Hope en route back to England. Just a few months earlier, Herschel had written to Lyell, in appreciation for Lyell’s Principles of Geology. He also commended Lyell’s boldness for addressing “that mystery of mysteries, the replacement of extinct species by others.” Lyell had not accepted transmutation at that point, but he had put the question prominently on the table. Herschel went on to endorse a Creator who “operates through a series of intermediate causes,” adding that if we were ever to understand the production of new species, it “would be found to be a natural in contradistinction to a miraculous process.”
Herschel’s view was about to become Darwin’s view, and the connection was not lost on Darwin. As he put it later, reflecting on his experience in the Galapagos, “Hence, both in space and time, we seem to be brought somewhat near to that great fact—that mystery of mysteries— the first appearance of new beings on this earth.” The same phrase appeared once again in the second sentence of the introduction to On the Origin of Species.
At some point in 1837, Darwin became convinced that transmutation had taken place on a wide scale. Partly, this resulted from the influence of Lyell’s gradualism: sudden changes, such as special creation, just would not do for scientific explanations. However, Darwin lacked a plausible mechanism for transmutation—how did it work? He did not find Lamarck’s idea—that traits acquired by an organism during its lifetime could be inherited by its offspring—very convincing.
Some of Darwin’s notebooks, such as this one, known as “Notebook B” from 1837-38, had long, narrow pages on which the user could write either across or down the page. Blank bound books of various types had been in use by scientists and many others for a long time; Robert Boyle had used them in the 1680s. On this page, which Darwin numbered “36” in the upper right corner, he wrote “I think” in the upper left corner and completed his thought with this famous diagram of a branching tree of life. Most Darwin manuscripts are now in the Cambridge University Library (image source), where I saw this particular notebook several years ago at a workshop sponsored by the Faraday Institute of Science and Religion.
Enter the Reverend Thomas Malthus: the Struggle to Survive
Darwin found the answer in the autumn of 1838, when he read Essay on the Principle of Population (1798 and seq.), by clergyman and political economist Thomas Robert Malthus. Near the end of his life, Darwin recalled reading Malthus simply “for amusement,” but we now know that it was actually part of a focused study he was then doing of the implications of evolution for human beings (quoting his Autobiography, p. 120). The problem that concerned Malthus was overpopulation. As he saw it, without applying artificial checks, rapidly increasing human population would inevitably outstrip slow advances in our ability to produce food, leading to widespread starvation. Furthermore, an increasing labor force would depress wages. His solution? Marry later in life, so that fewer children would be born. (It’s ironic that Darwin was reading that particular advice just as he was contemplating his own, relatively late, marriage to his first cousin Emma Wedgwood!)
The survival of Darwin’s notebooks puts historians like me in the anteroom of heaven: we get to see the ideas precisely as Darwin saw them, as they developed in his mind. In this case, here is what he wrote on 28 September 1838, in a commonplace book known by the glamorous name of “Notebook D”:
“The final cause of all this wedging, must be to sort out proper structure, and adapt it to change.—to do that for form, which Malthus shows is the final effect by means however of volition of this populousness on the energy of man. One may say there is a force like a hundred thousand wedges trying [to] force every kind of adapted structure into the gaps in the economy of nature, or rather forming gaps by thrusting out weaker ones.”
In the space of two sentences, Darwin took Malthus’ view of a grim struggle in the economy of man and read it into what he himself called “the economy of nature.” In the process, he obliterated William Paley’s benign natural theological vision of the wonderful “contrivances” of living things co-existing in a divinely created world. Indeed, he turned it upside down. Where Paley saw harmonious balance, extending even to predation, Darwin saw “a force like a hundred thousand wedges,” all trying to force their way into the same ecological niches, “by thrusting out weaker ones.”
Over the next six years, Darwin developed his theory enough to write it out at some length, first in a 35-page “Sketch” on natural selection (1842) and then in a much longer “Essay” of 230 pages (1844) that he wasn’t yet ready to publish. This was the situation when, in June 1858, he received an unpublished paper from Alfred Russel Wallace, an English naturalist living in the Maylay Islands who had independently hit upon the same idea of evolution by natural selection—also after reading Malthus. It was a remarkable coincidence, though not unique in the history of science.
Alfred Russel Wallace in the decade before he corresponded with Darwin about natural selection. Platinotype copy of a daguerreotype by unknown photographer (ca. 1842 or 1848), National Portrait Gallery, London, NPG x5108, given by the sitter's children, W.G. and Violet Wallace, 1916. Image used under license from creative commons.
What was Darwin to do? He was crushed, telling Lyell that “all my originality, whatever it may amount to, will be smashed.” It was decided that Darwin would quickly write a paper of his own, and that both papers would be read at an upcoming scientific meeting, along with a letter Darwin had recently written to Harvard botanist Asa Gray in which he discussed his theory—as a way of proving that he hadn’t stolen the central idea from Wallace.
Immediately Darwin got busy finishing the long-postponed book. Publisher John Murray printed just 1,250 copies that were all purchased by bookshops on the very same day of publication, 24 Nov 1859. There would be five more editions, the last (1872) quite different from the first. The title of the third chapter, “Struggle for Existence,” emphasizes the over-fecundity of living creatures in the face of limited resources. This results in a competition to survive and to produce progeny. As Darwin stated, this is “the doctrine of Malthus applied with manifold force to the whole animal and vegetable kingdoms; for in this case there can be no artificial increase of food, and no prudential restraint from marriage” (p. 63f). The next chapter, called “Natural Selection,” argues that useful variations, advantageous variations, tend to survive. “This preservation of favourable variations and the rejection of injurious variations, I call Natural Selection” (p. 81).
Enter Adam Smith: the Benefits of Competition
In addition to the influence of Malthus, which Darwin publicly acknowledged, there was also an important, unacknowledged influence from another British economist, the great Adam Smith, author of An Inquiry into the Nature and Causes of the Wealth of Nations (1776). Darwin read Smith during that crucial period from 1837 to 1838, when he seemingly read everything he could get his hands on and evolution was percolating in his mind. Although he didn’t spell out the connection explicitly, as he did with Malthus, it’s still unmistakably present—not only as found in Smith’s book itself, but also in the general worldview of a nineteenth-century English gentleman from an upwardly mobile family.
A leading expert on the history of evolution, Edward J. Larson, deftly connects the dots as follows:
“Darwinism represented simply one among many logical developments of an increasingly pervasive Western mindset that accepted competition among people or groups of people as socially beneficial. During the late 1700s, Adam Smith argued that economic progress depended on individual competition. His faith in the natural harmony of human interactions gave him hope that all people would benefit from laissez-faire capitalism. Embracing laissez-faire, Thomas Malthus soon observed that some individuals must gain and others lose in any social competition due to limited resources. Referring to the process as a ‘struggle for existence’ (at least in the context of primitive human societies), Malthus wrote of the ‘goad of necessity’ bringing out the best in people. … With Origin of Species, Darwin pushed this line of reasoning a critical step further by presenting competition as producing fitter varieties, races, and ultimately species.” (Evolution, p. 185)
Ed Larson, shown here taking notes on the back of a Galapagos tortoise, is a highly accomplished historian and legal scholar. His book about the Scopes trial, Summer for the Gods (1997), won the Pulitzer Prize for History. Among many other books, he has also written Trial and Error(1985), the definitive legal history of creationism; Evolution’s Workshop (2002), which includes an account of the life and work of ornithologist David Lack, an adult convert to Christianity and author of the famous book, Darwin’s Finches (1947); and an insightful book about the ethical, legal, and theological challenges posed by euthanasia (1988). Before becoming an academic, Larson worked for the US Congress and wrote the Equal Access Act, a significant piece of legislation upholding religious liberty. One of the most distinguished Christian scholars of his generation, Larson is a Lutheran, but since Malibu does not have a Lutheran church, he serves on the vestry at an Episcopal Church. Photograph by evolutionary biologist Rodney Honeycutt, courtesy of Edward J. Larson.
Furthermore, as Stephen Jay Gould insightfully pointed out, the parallel between Darwin’s natural selection and Smith’s “invisible hand” is remarkable. “The theory of natural selection is uncannily similar to the chief doctrine of laissez-faire economics” (cited below, p. 14). In both instances, there is no regulation from on high to govern the individual transactions; neither natural selection nor the invisible hand actually exists as a tangible entity, but each works to benefit the whole system.
In other words, just as Smith saw competition leading inevitably to specialization and diversification that enrich the economy of man, so Darwin saw competition leading inevitably to specialization and diversification that enrich the economy of nature.
Looking Ahead: Natural Selection, Politics, and Creationism Today
Whatever one may think of the evidence for common ancestry, the basic mechanism of natural selection was not very controversial then and is not very controversial now. Even young-earth creationists accept it. Why else would Ken Ham proclaim that “Natural Selection is Not Evolution!”? Writing about the antibiotic resistance of bacteria, Answers in Genesis biologist Georgia Purdom freely admits that, “the process of natural selection will occur, favoring the survival and reproduction of the mutant bacteria.” She even goes so far as to call this phenomenon “a testimony to the wonderful design God gave bacteria, master adapters and survivors in a sin-cursed world.” Creationists draw the line, however, at any effort to equate natural selection with evolution: adaptation governed by natural selection, in their view, operates only within, not across, the genetic boundaries of the original created “kinds,” whatever they were. I can almost hear Darwin laughing, since for him natural selection was inseparable from evolution.
Those Christians who have come to terms with Darwin, including myself, continue to struggle with the struggle Darwin saw in nature. How can a good God and a “very good” creation be reconciled with evolution by natural selection? There are no easy answers here, but I offered some pointers toward possible answers in another series. If nature does indeed have a cruciform shape, then perhaps this is not really quite so surprising.
The climax of this series comes next time, when I present my interpretation of evolution and Darwin’s God.