Review: The Greatest Show On Earth: The Evidence for Evolution byRichard Dawkins (New York: Free Press, 2009)
Some years ago an anonymous well-wisher sent Richard Dawkins a T-shirt bearing the slogan “Evolution: The Greatest Show on Earth.” The T-shirt inspired Dawkins with the title for his latest book, which he describes as his “personal summary of the evidence that the ‘theory’ of evolution is actually a fact—as incontrovertible a fact as any in science” (p. vii).
Dawkins is a good writer, and his book is quite entertaining, so it is appropriate that he named it after the famous Ringling Brothers and Barnum and Bailey circus. Let’s imagine The Greatest Show on Earth as a three-ring circus being performed before an audience of farm families somewhere in the Midwest.
The first ring holds the menagerie. In the center, a towering Great Dane peers down at a tiny Chihuahua. Ringmaster Dawkins announces to the audience that these dogs prove beyond any conceivable doubt that all living things are descended from a common ancestor, modified by the amazing, death-defying power of natural selection. “Anybody can understand the principle of evolution by artificial selection,” he explains (p. 28). And “artificial selection is not just an analogy for natural selection. Artificial selection constitutes a true experimental—as opposed to observational—test of the hypothesis that natural selection causes evolutionary change” (p. 66).
The kids in the audience stare wide-eyed at the two dogs. The grown-ups, however, shake their heads in disbelief. As farmers, they know that dogs remain dogs no matter how long you breed them. Evolution, indeed!
The first ring also has a cage full of birds, bees, and moths that are marvelously adapted to extract nectar from nearby flowers—and in the process spread their pollen. Another cage holds flightless birds and flying mammals, and a large tank holds brightly colored guppies and marine iguanas. The ringmaster explains how these also prove that “our common ancestry with porcupines and pomegranates” is a fact “beyond serious doubt, beyond sane, informed, intelligent doubt” (pp. 8, 16).
Some in the crowd start to boo, but an African antelope suddenly charges out, pursued by a lioness that drags it down and makes a meal of it. The ringmaster announces that the “arms race between the gene pools of the two species is run in evolutionary time” (color pp. 30-31) and this explains how they evolved from a common ancestor. The audience is too startled to react.
The second ring contains the magicians and jugglers. In the center is Michigan State University biologist Richard Lenski, wearing a white lab coat and holding some liquid-filled flasks. The ringmaster announces that Lenski’s experiments “are distressing to creationists, and for a very good reason. They are a beautiful demonstration of evolution in action, something it is hard to laugh off even when your motivation to do so is very strong” (p. 117). Lenski’s experiments show that artificial selection over tens of thousands of generations can cause E. coli bacteria to change their metabolism slightly. The grownups in the audience wonder what this proves, since the bacteria in Lenski’s flasks are still E. coli.
Though the ringmaster uses “creationist” repeatedly, he never defines it. Usually he seems to mean people who believe the Earth was created just a few thousand years ago. In the Lenski act, however, the unnamed and unseen “creationist” is not a young-Earther, but Lehigh University biochemist Michael J. Behe. Behe has published scientific critiques of Lenski’s work, and the ringmaster defends Lenski against them, but he never acknowledges Behe’s existence. Even the kids in the audience groan at this cheap disappearing act; they know that a good magician would at least show them the victim before making him vanish.
Off to one side is Norwegian paleontologist Jørn Hurum, whose act was added to the program at the last minute. Hurum holds up a hat, out of which he pulls a cat-sized fossil named Darwinius masillae,nicknamed “Ida.” Ida looks like a lemur, but Hurum calls it the oldest link to human beings, the scientific equivalent of the Holy Grail, the long-awaited confirmation of Darwin’s theory of evolution. The ringmaster hastens to point out that Darwin’s theory was “confirmed long ago,” though he says that the fossil “will certainly shed some light on our ancestry” (color p. 9).
The announcement of Ida in a scientific journal in May 2009 (just before Dawkins’s circus hit the road) was accompanied by a huge fanfare that included a press conference and a TV special. By October 2009, however, Ida had been discredited. Scientists realized it was not part of the human lineage; in fact, it may have left no descendants at all. Adding Hurum’s act to The Greatest Show on Earth was an embarrassing mistake.
Also in the second ring stands a juggler tossing three sets of bones in the air: a human hand, a bat’s wing, and a small horse’s foreleg. The ringmaster explains, “The human hand and the bat hand are obviously—no sane person could deny it—two versions of the same thing” (p. 288). Although the horse’s leg is not as similar as those two, it also retains “unmistakable traces of the original” (p. 291). This “pattern of resemblances among the skeletons of modern animals is exactly the pattern we should expect if they are all descended from a common ancestor” (p. 295).
“Are there any alternative explanations?” asks the ringmaster. “Well, just barely! The hierarchical pattern of resemblances was spotted by creationists in pre-Darwinian times, and they did have a non-evolutionary explanation—an embarrassingly far-fetched one. Patterns of resemblance, in their view, reflected themes in the mind of the designer” (p. 296). The ringmaster ridicules that explanation, stating that “there is a strong element of special pleading and wishful thinking” (p. 297) in it.
Many people in the audience shake their heads, since the idea that such similarities “reflect themes in the mind of the designer” makes perfect sense to them. A few people also know that the “creationists in pre-Darwinian times” were not young-Earth creationists, but included world-renowned anatomist Richard Owen. Beyond mocking the design alternative, however, the ringmaster offers no justification for his claim that similarities in the juggled bones were inherited from a common ancestor.
The third ring contains the clowns. One with a white face and big, bulging eyes on the back of his head is running around backwards. The ringmaster explains that he is making fun of the vertebrate retina, which is “badly designed” because it is “back to front” in the sense that the light detecting rods and cones face away from the pupil. According to the ringmaster, the vertebrate eye is a “glaring example of imperfection,” a “catastrophic blunder” (pp. 353, 355) that proves our eyes were not designed, but evolved.
The audience howls with laughter. The kids laugh at the clown, while the grownups laugh at the ringmaster. They know that the hawks preying on their chickens have extraordinary eyesight. A few in the audience who are medically trained also know that the rods and cones in our retinas face away from the light because they require a blood-rich tissue to nourish them. If the retina were constructed the way the ringmaster imagined it should be, the blood-rich tissue would be in front of the rods and cones, blocking the light.
Another whiteface clown dances around the ring waving a miniature tree with pictures of various animals at the tips of its branches. The ringmaster explains that this is Darwin’s Tree of Life, which shows how all living things spring from a common ancestor (the trunk). Evolutionary biologists used to rely on anatomical comparisons to construct such trees, but now they compare DNA sequences as well. “What turns this into extremely powerful evidence for evolution,” the ringmaster proclaims, “is that you can construct a tree of genetic resemblances separately for each gene in turn, and the important result is that every gene delivers approximately the same tree of life. Once again, this is exactly what you would expect if you were dealing with a true family tree,” (pp. 321-322) but not what you would expect from a designer.
The kids laugh at the clown. Some grownups laugh, too — at the ringmaster. They have studied enough biology to know that different genes can yield different evolutionary trees; in fact, the same gene can yield different trees when analyzed by different laboratories. As more genes are included, the problem gets worse. A 2005 article in Science reported a study comparing fifty genes in seventeen animal groups and noted that different analyses can produce significantly different trees, each seemingly supported by solid evidence.
Apparently without realizing that many in the audience were laughing at him, the ringmaster introduces one more clown—a hobo like Emmett Kelly, trying to sweep up the light from a spotlight moving across the floor. Projected in the middle of the spot is the word “pseudogene.” The ringmaster explains that pseudogenes “are genes that once did something useful but have now been sidelined and are never transcribed or translated” (p. 332). The ringmaster continues: “What pseudogenes are useful for is embarrassing creationists. It stretches even their creative ingenuity to make up a convincing reason why an intelligent designer should have created a pseudogene… unless he was deliberately trying to fool us” (p. 332).
While the kids laugh at the clown, the biologically literate grownups get their last laugh of the day at the ringmaster. They know that so-called pseudogenes (like virtually all DNA sequences) are transcribed; even though they may not produce proteins, they perform important biological functions. After the show, some people wonder whether the ringmaster knew he was being funny.
Sadly, no. Dawkins expects The Greatest Show on Earth to be taken seriously. A serious reader, however, would note that the book’s arguments rest on equivocation. Dawkins uses “evolution” to mean things as different as changes within existing species, the origin of species, and the common ancestry of all living things; and he uses “creationism” to mean things as different as young-Earth creationism, pre-Darwinian biology, and Intelligent Design. Dawkins also gets much of his biology wrong: Behe’s critiques of Lenski’s work remain valid; Darwinius masillae tells us nothing about human ancestry; vertebrate retinas are not “catastrophic blunders,” but remarkably efficient organs of sight; gene comparisons are not converging on a single tree of life, but are plagued with inconsistencies; and so-called pseudogenes are not useless junk, but biologically functional. In a book that claims to present the “evidence for evolution,” these are serious defects, and they deserve serious criticism.
Maybe it’s kinder just to laugh.