Darwin and Ecology

I’d forgotten all about it. Back in 1992 I wrote an article for a minor journal, “Charles Darwin’s Influence on Ecological Theory.” The editor accepted it for publication, but wanted revisions. I was going through a job change right then, and chose to drop the project. The article itself is outdated, and not well written. I am unwilling to revise and post it. But in this essay I will summarize some of its main points.

Here is the abstract:

“Prior to Charles Darwin, ecological relationships between organisms and their environments, and among organisms, were interpreted in terms of the Great Chain of Being, of bidirectional adaptation, and of the Balance of Nature. Darwin made valuable contributions to ecology through his careful measurements of plant and animal populations, and his understanding of the complexity of interactions among plant and animal species. But his major contribution to ecological theory was that natural selection, the evolutionary mechanism he proposed, made the Great Chain of Being and Balance of Nature concepts obsolete.

Many twentieth century ecologists believed that communities of plants and animals were superorganisms and functioned as organisms in their own right. The superorganism concept was irreconcilable with Darwinian natural selection, and only recently has ecological theory come to terms with this. For the Darwinian view of ecology to be fully successful, a response must be made to the recent proposal of a modified superorganisms concept, the Gaia Hypothesis.”

This is all interesting, even though not too original, even in 1992. You can read a lot about pre-Darwinian ecology in Ernst Mayr’s book The Growth of Biological Thought and many essays by Stephen Jay Gould.

Here is a summary of the article, which I have made as interesting as possible, but which remains (fair warning) somewhat heavy going compared to most essays on this blog.

The term ecology was first used, apparently, by Reiter in 1885 and Haeckel in 1886. St. George Jackson Mivart came up with his own version of it, which he called hexicology. (I used to think Mivart was a Catholic saint, but St. George is just his first name. He got in trouble with the Catholic church when he wrote “Happiness in Hell”.)

Even in the twentieth century, ecologists (who, like Frederic Clements, considered themselves Darwinians) thought the natural world functioned as an organism and therefore kept itself “in balance” the way your physiology stays in balance. Another example is Victor Shelford. Arthur Tansley quickly pointed out that an ecological community was a super-organisms but does not resemble an individual organism. Nevertheless the super-organism concept has led to some humorous examples. Some of its practitioners liked to walk through a Pinetum (a pine woodland) or a Quercetum (an oak forest). This approach continued until at least 1991. The idea that plant communities are discrete and nameable like organisms was eclipsed largely by Robert Whittaker’s vegetation studies starting in 1956.

For centuries, thinking about the natural world was constrained by the Scala Naturae and what I call a bidirectional view of adaptation.

First, the Scala Naturae was like a great ladder of life that included not only organisms but was a seamless fabric that included minerals (such as the fibrous asbestos) at its base. Because all of the links in the chain must exist, even pre-Darwinian scientists such as Linnaeus accepted human-ape intermediates such as Homo troglodytes and Homo sylvestris. Darwin’s research shattered the Chain.

Classification schemes were based on almost anything other than Darwin’s branching tree of life. Some were based on mathematical symmetry, such as the quinarian systems proposed by MacLeay in 1819 and Swainson in 1835. Strickland wrote in 1846 that these patterns reflected God’s pattern of thought during creation. Darwin’s research shattered these ideas. These systems had an artistic, rather than functional, completeness: species existed because the symmetry demanded them, not because of ecological opportunity, much less evolution.

Second, by bidirectional adaptation, I mean the idea that organisms fitted their environments, and the environment fitted the organisms. Edward Blyth’s 1837 example (cited in Loren Eiseley’s Darwin’s Century) was that the ptarmigan was adapted to the mountaintop and the mountaintop to the ptarmigan. Blyth’s idea was in such contrast to Darwin that Eiseley’s assertion (Darwin and the Mysterious Mr. X) that Darwin got the idea of natural selection from him seems unbelievable. No scientist believes now that the environment adapts itself to organisms.

The Balance of Nature was also an old idea. Herodotus believed that a superintending providence kept predators from eating all of their prey, mainly because the prey had high reproductive rates. Similar ideas are found in Plato, Cicero, and Plotinus. Linnaeus wrote in 1759 that “…all natural things…lend a helping hand towards preserving every species…” Herbivores, for example, kept any one plant species from crowding out the others. Buffon had similar beliefs. Perhaps the most famous and extensive defense of this idea was in Paley’s Natural Theology (1802), one of the most famous pre-Darwinian science books. “Perhaps there is no species of terrestrial animals whatever, which would not overrun the earth, if it were permitted to multiply in perfect safety; or of fish, which would not fill the ocean…” Superfecundity, he explained, had two advantages: “first, that it tends to keep the world always full; whilst…it allows the proportion between the several species of animals to be differently modified …as different situations may afford them room and food…One species of insects rids us of another species…” Anticipating chapter 3 of Darwin’s Origin of Species, Paley wrote, “An elephant produces but one calif; a butterfly lays six hundred eggs…In the rivers, we meet with a thousand minnows for one pike; in the sea, a million herrings for a single shark.” Paley, and most pre-Darwinian scientists, believed that the relationships among species were designed by God just as were their bodily characteristics. You can read more in the Egerton article [].

Darwin not only passed on these concepts of ecological complexity, but painstakingly counted the number of plant seedlings that emerged from a cleared plot of land, and how many of them died. John L. Harper described this as Darwin’s “preoccupation with numbers” in “A Darwinian approach to plant ecology” (1967). Most famously, Darwin linked the abundance of clover to that of house cats, via mice and bumblebees. His metaphor of the Entangled Bank depicted the impossibility of explaining all the ecological interactions. You might as well, he said, throw up a handful of feathers and try to predict where each would fall using only the laws of physics.

Alfred Russel [one L] Wallace found examples in his extensive travels that the world was not made for man’s benefit, for example birds of paradise that live in tropical mountains inaccessible to humans, and durian fruits which can kill people when they fall from the tree. Later in life, during his period of spiritualism, Wallace asserted that the world was made for man, a view ridiculed by (who else) Mark Twain.

Popular nature writing is still filled with pre-Darwinian views. Most people believe that flowers and pollinators help each other out, as a law of nature. But in a Darwinian view, flowers that can trick their pollinators into servicing them without having to provide any benefit might prevail, and pollinators will steal nectar if they can get away with it. Ecologists use terms such as “larcenous” insects and “deceptive” flowers.

And the idea that ecology must have been designed by God persists in creationist literature.

The Gaia hypothesis was not intended to be anti-Darwinian but invokes a planetary-level homeostasis that is difficult to reconcile with Darwinian natural selection. I concluded in 1992, “Thus ecologists are left with the question of whether the earth just happens to remain in apparent homeostasis, because of Darwinian natural selection acting on individuals, or whether the earth keeps itself in real homeostasis…” As I understand, this is still the case.