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 The article itself is outdated, and not well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.