Bully for Brontosaurus (22 page)

La Rosa was also gracious enough to add: “And yes, though time does distort the memory, I wouldn’t be surprised if I was flat the day he, Mr. Wilhousky, singled me out. I was terrified—and probably didn’t take a good deep breath!!” (Actually, I don’t doubt for a moment that both La Rosa’s version and what I heard ten years later from Wilhousky are entirely accurate. We scarcely need
Rashomon
to teach us that rich events are remembered for different parts and different emphases—so that equally accurate, but partial versions yield almost contradictory impressions.)

And if La Rosa’s reference to Jeanette (
not
Madame) puzzled you, let me close with his ultimate touché from earlier in his letter:

TEDDY ROOSEVELT
borrowed an African proverb to construct his motto: Speak softly, but carry a big stick. In 1912, a critic turned Roosevelt’s phrase against him, castigating the old Roughrider for trying to demolish an opponent by rhetoric alone: “Ridicule is a powerful weapon and the temptation to use it unsparingly is a strong one…. Even if we don’t agree with him [Roosevelt’s opponent], it is not necessary either to cut him into little pieces or to break every bone in his body with the ‘big stick.’”

This criticism appeared in the midst of Roosevelt’s presidential campaign (when he split the Republican party by trying to wrest the nomination from William Howard Taft, then formed his own Progressive, or Bull Moose, party to contest the election, thereby scattering the Republican vote and bringing victory to Democrat Woodrow Wilson). Surely, therefore, the statement must record one of Roosevelt’s innumerable squabbles during a tough political year. It does not. Francis H. Allen published these words in an ornithological journal,
The Auk
. He was writing about flamingos.

When, as a cynical and posturing teenager, I visited Mount Rushmore, I gazed with some approval at the giant busts of Washington, Jefferson, and Lincoln, and then asked as so many others have—what in hell is Teddy Roosevelt doing up there? Never again shall I question his inclusion, for I have just discovered something sufficiently remarkable to warrant a sixty-foot stone likeness all by itself. In 1911, an ex-president of the United States, after seven exhausting years in office, and in the throes of preparing his political comeback, found time to write and publish a technical scientific article, more than one hundred pages long: “Revealing and Concealing Coloration in Birds and Mammals.”

Roosevelt wrote his article to demolish a theory proposed by the artist-naturalist Abbott H. Thayer (and defended by Mr. Allen, who castigated Roosevelt for bringing the rough language of politics into a scientific debate). In 1896 Thayer, as I shall document in a moment, correctly elucidated the important principle of countershading (a common adaptation that confers near invisibility upon predators or prey). But he then followed a common path to perdition by slowly extending his valid theory to a doctrine of exclusivity. By 1909, Thayer was claiming that
all
animal colors, from the peacock’s tail to the baboon’s rump, worked primarily for concealment. As a backbreaking straw that sealed his fate and inspired Roosevelt’s wrath, Thayer actually argued that natural selection made flamingos red, all the better to mimic the sunset. In the book that will stand forever as a monument to folly, to cockeyed genius, and to inspiration gone askew, Thayer stated in 1909 (in
Concealing-Coloration in the Animal Kingdom
, written largely by his son Gerald H. Thayer and published by Macmillan):

Roosevelt responded with characteristic vigor in his 1911 article:

Roosevelt’s critique (and many others equally trenchant) sealed poor Thayer’s fate. In 1896, Thayer had begun his campaign with praise, promise, and panache (his outdoor demonstrations of disappearing decoys became legendary). He faced the dawn of World War I in despair and dejection (though the war itself brought limited vindication as our armies, used his valid ideas in theories of camouflage). He lamented to a friend that his avocation (defending his theory of concealing coloration) had sapped his career:

I must end this preface to my essay with a confession. I have known about Thayer’s “crazy” flamingo theory all my professional life—and for a particular reason. It is the standard example always used by professors in introductory courses to illustrate illogic and unreason, and dismissed in a sentence with the ultimate weapon of intellectual nastiness—ridicule that forecloses understanding. When I began my research for this essay, I thought that I would write about absurdity, another comment on unthinking adaptationism. But my reading unleashed a cascade of discovery, leading me to Roosevelt and, more importantly, to the real Abbott Thayer, shorn of his symbolic burden. The flamingo theory is, of course, absurd—that will not change. But how and why did Thayer get there from an excellent start that the standard dismissive anecdote, Thayer’s unfortunate historical legacy, never acknowledges? The full story, if we try to understand Abbott Thayer aright, contains lessons that will more than compensate for laughter lost.

Who was Abbott Handerson Thayer anyway? I had always assumed, from the name alone, that he was an eccentric Yankee who used wealth and social postion to gain a hearing for his absurd ideas. I could find nothing about him in the several scientific books that cite the flamingo story. I was about to give up when I located his name in the
Encyclopedia Britannica
. I found, to my astonishment, that Abbott Thayer was one of the most famous painters of late nineteenth century America (and an old Yankee to be sure, but not of the wealthy line of Thayers—see the biography by Nelson G. White,
Abbott H. Thayer: Painter and Naturalist
). He specialized in ethereal women, crowned with suggestions of halos and accompanied by quintessentially innocent children. Art and science are both beset by fleeting tastes that wear poorly—far be it for me to judge. I had begun to uncover a human drama under the old pedagogical caricature.

But let us begin, as they say, at the beginning. Standard accounts of the adaptive value of animal colors use three categories to classify nature’s useful patterns (no one has substantially improved upon the fine classic by Hugh B. Cott,
Adaptive Coloration in Animals
, 1940). According to Cott, adaptive colors and patterns may serve as (1) concealment (to shield an animal from predators or to hide the predator in nature’s never-ending game); (2) advertisement, to scare potential predators (as in the prominent false eyespots of so many insects), to maintain territory or social position, or to announce sexual receptivity (as in baboon rump patches); and (3) disguise, as animals mimic unpalatable creatures to gain protection, or resemble an inanimate (and inedible) object (numerous leaf and stick insects, or a bittern, motionless and gazing skyward, lost amidst the reeds). Since disguise lies closer to advertisement than to concealment (a disguised animal does not try to look inconspicuous, but merely like something else), we can immediately appreciate Abbott Thayer’s difficulty. He wanted to reduce all three categories to the single purpose of concealment—but fully two-thirds of all color patterns, in conventional accounts, serve the opposite function of increased visibility.

Abbott Thayer, a native of Boston, began his artistic career in the maelstrom of New York City but eventually retreated to a hermitlike existence in rural New Hampshire, where his old interests in natural history revived and deepened. As a committed Darwinian, he believed that all form and pattern must serve some crucial purpose in the unremitting struggle for existence. He also felt that, as a painter, he could interpret the colors of animals in ways and terms unknown to scientists. In 1896, Thayer published his first, landmark article in
The Auk:
“The Law Which Underlies Protective Coloration.”

Of course, naturalists had recognized for centuries that many animals blend into their background and become virtually invisible—but scientists had not properly recognized how and why. They tended to think, naively (as I confess I did before my research for this essay), that protection emerged from simple matching between animal and background. But Thayer correctly identified the primary method of concealment as countershading—a device that makes creatures look flat. Animals must indeed share the right color and pattern with their background, but their ghostly disappearance records a loss of dimensionality, not just a matching of color.

In countershading, an animal’s colors are precisely graded to counteract the effects of sunlight and shadow. Countershaded animals are darkest on top, where most sunlight falls, and lightest on the bottom (Thayer thereby identified the adaptive significance of light bellies—perhaps the most universal feature of animal coloration). The precise reversal between intensity of coloration and intensity of illumination neatly cancels out all shadow and produces a uniform color from top to bottom. As a result, the animal becomes flat, perfectly two-dimensional, and cannot be seen by observers who have, all their lives, perceived the substantiality of objects by shadow and shading. Artists have struggled for centuries to produce the illusion of depth and roundness on a flat canvas; nature has simply done the opposite—she shades in reverse in order to produce an illusion of flatness in a three-dimensional world.

Contrasting his novel principle of countershading with older ideas about mimicry, Thayer wrote in his original statement of 1896: “Mimicry makes an animal appear to be some other thing, whereas the newly discovered law makes him cease to appear to exist at all.”

Thayer, intoxicated with the joy of discovery, attributed his success to his chosen profession and advanced a strong argument about the dangers of specialization and the particular value of “outsiders” to any field of study. He wrote in 1903: “Nature has evolved actual art on the bodies of animals, and only an artist can read it.” And later, in his 1909 book, but now with the defensiveness and pugnacity that marked his retreat:

So far, so good. Thayer’s first articles and outdoor demonstrations won praise from scientists. He began with relatively modest claims, arguing that he had, elucidated the basis for a major principle of concealment but not denying that other patterns of color displayed quite different selective value. Initially, he accepted the other two traditional categories—revealing coloration and mimicry—though he always argued that concealment would gain a far bigger scope than previously admitted. In his most technical paper, published in the
Transactions of the Entomological Society of London
(1903), and introduced favorably by the great English Darwinian E. B. Poulton, Thayer wrote:

Indeed, Thayer sought ways to combine ideas of concealment with other categories that he would later deny. He supported, for example, the ingenious speculation of C. Hart Merriam that white rump patches are normally revealing, but that their true value lies in a deer’s ability to “erase” the color at moments of danger—a deer “closes down” the patch by lowering its tail over the white blotch and then disappears, invisible, into the forest. In his 1909 book, however, Thayer explicitly repudiated this earlier interpretation and argued for pure concealment—the white patch as “sky mimicking” when seen from below.

Thayer’s pathway from insight to ridicule followed a distressingly common route among intellectuals. Countershading for concealment, amidst a host of alternatives, was not enough. Thayer had to have it all. Little by little, plausibly at first, but grading slowly to red wings in the sunset, Thayer laid his battle plans (not an inappropriate metaphor for a father of camouflage). As article succeeded article, Thayer progressively invaded the categories of mimicry and revealing coloration to gain, or so he thought, more cases for concealment. Finally, nothing else remained:
All
patterns of color served to conceal. He wrote in his book: “All patterns and colors whatsoever of all animals that ever prey or are preyed upon are under certain normal circumstances obliterative.”

Thayer made his first fateful step in his technical article of 1903. Here, he claimed a second major category of concealing coloration—what he called “ruptive” (we now call them “disruptive”) bars, stripes, splotches, and other assorted markings. Disruptive markings make an animal “disappear” by a route different from countershading. They break an animal’s coherent outline and produce an insubstantial array of curious and unrelated patches (this principle, more than countershading, became important in military camouflage). A zebra, Thayer argues, does not mimic the reeds in which it hides; rather, the stripes break the animal’s outline into bars of light and darkness—and predators see no coherent prey at all.