Editor's Introduction -- The writers of junky science books like
to rhapsodize about nature's "balance," but they never disclose
what it is or how it can be recognized. In truth, their notion of
a "balance" is a mystical fiction. It is derived not from science
but from 19th-century religion, and it collapses as soon as we ask
a few questions.
The article below -- which appeared as a sidebar to a review of Kendall/Hunt's Middle School Life Science (1991) -- tells of some schoolbook-writers who dispensed mystical claims about "balance" and augmented them with a quaint exhibition of anthropomorphism. Anthropomorphism, epitomized in Bambi, is the practice of ascribing human properties, faculties and emotions to non-human organisms.
from The Textbook Letter, September-October 1992
Old Paley Strikes Again
William J. BennettaThe "Ecosystems and Ecology" unit within Middle School Life Science offers a passage titled "Ecosystem Balance." It has almost nothing to do with science but is rich in the delusions that some textbooks dispense as "science" to unfortunate students:
Predation -- the preying of one animal on another -- is not only essential for the survival of the predator, it also plays an important role in the balance of an ecosystem. Predators help control the size of their prey populations. Without predation, prey populations would grow so quickly that the ecosystem would suffer. For example, in the early 1900s, the ranchers in the Kaibab plains near the Grand Canyon killed many of the local wolves and coyotes. Without these predators, more deer survived. After several years, there were so many deer that food became scarce and thousands of deer starved to death.
The entire passage is founded on natural theology, a corpus of religious doctrine propounded some 200 years ago by the English churchman William Paley. [See "When the Shark Bites with His Teeth, Dear, Remember That It's All for the Best," in TTL for November-December 1991.] Paley and his followers promoted a view of nature that remains popular today but has no scientific basis at all -- a view in which predators and prey are allies, graciously helping each other to prosper and to preserve a mystical, divinely ordained condition that usually is called "the balance of nature." In Middle School Life Science, as we see, it is called "the balance of an ecosystem."
Honoring a sacred tradition of natural theology, the writers neglect to say what "the balance of an ecosystem" is or how it may be recognized. They merely cite a case involving canids and deer, then leave the reader to imagine that this illustrates or confirms the unexplained notion of a "balance."
That is nonsense. The cited case shows an apparent link between the size of a predator population and the size of a of a prey population, but it does not answer our questions: Why do the writers obviously think a proper "balance" prevailed when the deer population was limited by predation, but not when the deer population (later) was limited by its food supply? Is predation more proper than starvation as a population-limiting agent? Who says so -- and why? When things were in "balance," before ranchers intervened, what factors limited the canid population? Might those factors have included the canids' supply of food (i.e., the supply of deer)? If so, please tell: Why was there a proper "balance" when a canid population was being limited by its food supply, but not when a deer population (later) was being limited in the same way?
In their second paragraph, the writers soar farther into fantasy: "Predators usually capture the old, crippled, sick, or very young animals." That is a favorite of the natural-theology crowd; maybe they think it sounds like something that a supernatural creator might ordain if he wanted to make nature look benign, or at least rational. But think of a baleen whale as it plows along and engulfs all the krill in its path, old and young alike, sick and healthy together. Think of other filter-feeders. Think of a bluefish killing its way through a school of herring. Think of a beetle feeding on aphids. Think of a man netting salmon. And ask this: Where can we observe the prey populations that the writers describe -- populations so loaded with old, crippled, sick or very young animals that predators "very rarely" need to take healthy adults?
Having described a mystical protocol for predation, the writers now tell its imaginary result: "In this way, only the strongest and smartest animals are left to reproduce." What is the evidence for that? Can anybody even identify the strongest krill or the smartest aphids, let alone showing that their strength and smartness enables them to escape predation? I doubt it. I think that the writers are simply embellishing natural theology with Bambi stuff. Their strange preoccupation with the "strongest and smartest" gives them away. Why should survival and reproductive success require only that an animal be strongest and smartest? Why not best-camouflaged, loudest, most heavily armored, most buoyant, most richly endowed with scent glands, or most resistant to desiccation? The evident answer is that the writers are mired in anthropomorphism: Because strength and smartness seem to be important in the life of a human, the anthropomorphist imagines that those traits rule the life of every other organism too. That was fine in Bambi, but in a "science" book it is intolerable.
To end their religious tale, the writers say: "Over long periods of time, predation actually improves the health of the prey population." I don't know what that means, but I do know that over long (or even short) periods of time, predation can drive a prey population to extinction. That's health?
William J. Bennetta is a professional editor, a fellow of the California Academy of Sciences, the president of The Textbook League, and the editor of The Textbook Letter. He writes frequently about the propagation of quackery, false "science" and false "history" in schoolbooks.
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