The Greatest Show On Earth: The Evidence for Evolution by Richard Dawkins

The Greatest Show On Earth: The Evidence for Evolution by Richard Dawkins
The Greatest Show on Earth: The Evidence for Evolution
by Richard Dawkins
Free Press, 480 pp.
CLR [rating:5]

A Defender of Science

Comments abound on Richard Dawkins latest book, The Greatest Show on Earth: The Evidence for Evolution. Most are laudatory. Dawkins is a public intellectual and a master of evolutionary biology and has been a best selling author for years. For example, The God Deluson, (2006) still remains on best seller lists. Then there is a vocal core of detractors who seem to fervently wish that he and his book would burst into flames. This would prove once and for all God’s wisdom and providence as well as the unerring literal truth of the creation stories of Genesis.

“What,” Dawkins queries, “…if you are a teacher…and your lessons on twentieth–century Europe are boycotted, heckled, or otherwise disrupted by well-organized, well financed and politically muscular groups of Holocaust deniers. …They are vocal, superficially plausible, and adept at seeming learned. …. Imagine that you, as a teacher of European history, are continually faced with belligerent demands to ’teach the controversy’, and to give ‘equal time’ to the ‘alternative theory’ that the Holocaust was fabricated by a bunch of Zionist fabricators….”

Dawkins asserts that the plight of beleagured science teachers is similar to that of this history teacher. This is particularly true in the U.S. and increasingly so in Europe. There, new wave Muslim immigrants, very much like their evangelical Christian cousins, aggressively inveigh againt evolution. Dawkins’ The Greatest Show on Earth aims toward correcting the errors of evolution deniers.

To understand fully the painstaking, richly exemplified, cooly analytical methodology by which Dawkins reaches his conclusions necessitates reading the book. A brief, much condensed sampling follows.

In defining and illustrating artificial selection that is the basis of evolutionary theory, Dawkins notes the following.

Human Selection: human selection is seen in the remarkable variety of, for instance, dogs. From the jittery Chihuahua to the staid Saint Bernard and a hundred varieties in between, all of them are descended, with human selection, from the wolf, Canis Lupis.

It is important to realize that these changes were accomplished in a relatively short period of time—centuries or millennia—no more than the blinking of an eye compared with the thousands millennia of geologic time. The times involved are important because of a notion, beloved by many evangelical Christians, that the earth is a mere 6,000 years old.

Natural Selection: Darwin’s great insight was that there need be no external agent for selective breeding to occur. Nature plays the role of breeder. Tiny fish choose to approach enticing angler fish—and are eaten. This helps select for the survival and reproduction of the attractive predator with its built in fishing pole.

This concept exemplifies Darwin’s great discovery. There is no external choosing agent needed. In this natural process those individiuals are selected simply by the fact that they happen to possess superior equipment to survive. “They are the most likely to reproduce, and therefore pass on genes for possessing superior equipment for survival and reproduction.”

Nature has provided many “clocks” that serve to date fossils, rock strata, and the earth itself to a high degree of accuracy. Examples of the many dating methods Dawkins explains include:

Radioactive clocks: they are based on a knowledge of atomic theory. A central core of protons and neutrons of the same mass form the nucleus of, say, a carbon atom, the “sun” in this Lilliputian solar system. Electrons of negligible mass buzz around the nucleus like planets. Carbon comes in a number of varieties. The number of protons in the center of the atom is constant, the number of neutrons is not. Carbon 12, for instance, has 6 protons and 6 neutrons. There also exists a Carbon 14; a radioactive isotope with 6 neutrons and 8 protons. Because of the energy of cosmic radiation, some ordinary nitrogen, nitrogen 14, gains an electron and a neutrino and is thus changed to carbon 14 in the upper atmosphere. Carbon 14 is a radioactive form, or isotope, of the much more common carbon-12. Living creatures incorporate either carbon equally well. After a plant or animal dies, there is no replenishment of the isotope.

Carbon 14, like a house of cards, is unstable. It decays, “falls apart,” at a known rate, losing that extra neutrino and electron and becoming ordinary nitrogen 14 again. Half of the carbon 14 present disappears in this manner every 5,739 years. Careful measurement tells how much is left of the carbon 14 that was there when the creature or plant died, thus dating the remains.

Living creatures use carbon 12 and carbon 14 equally well. Plants incorporate it with water, making sugars. Carbon 14 in the atmosphere is constantly replenished. But when a plant or animal dies, the clock is ”zeroed,” because no further Carbon 14 is added to the system. The half life of carbon-14 is brief enough that it can be correlated well with, for instance, the “clock” of living and fossilized tree rings studied by the dendrochronologist. The accuracy of carbon 14 dating is plus or minus one century. Thus in the case of, “…the Shroud of Turin, three tiny samples (of the flax from which the cloth was woven) were dated independently by three different labs, with the resulting conclusions: Oxford AD 1200. Arizona 1304 and Zurich 1274. There dates are all within normal margins of error and compatable with each other as well as with the date in the 1350s at which the shroud is first mentioned in history.” Many other clocks based on atomic theory are also available, some of billions of years.

The molecular clock: the double strands of DNA that carry our genetic makeup are 95 per cent inactive. Changes occur at a known rate in this part of our DNA at the molecular level—changes that make no difference to external apearance, but which are measaurable. The unit of measure is a “Darwin,” so named by famed geneticist J. B. S. Haldane. One of the architects of modern Darwinism, he served with great courage in the Scottish Blackwatch Regiment during World War I, then continued his research. At that time, there were some 350,000 known species of beetles. When Haldane was asked by a theologian what he learned of the nature of God from his study of science, he replied, “That He has an inordinate fondness for beetles.”

It was also Haldane who was challenged by an evolution skeptics who stated, ”Even given the billions of years that you say were available for evolution, I simply cannot believe it is possible to go from a single cell to a complicated human body with its trillions of cells organized into bones and muscle and nerves, a heart that pumps without ceasing for decades, miles and miles of blood vessels and kidney tubules, and a brain capable of thinking and feeling.”

“But Madam,” he replied, “you did it yourself. And it only took nine months.”

Dawkins notes parenthetically that, “The popular canard about Hitler being inspired by Darwin comes partly from the fact that both Hitler and Darwin were impressed by something that everybody had known for centuries: you can breed animals for desired qualitites. Hitler aspired to turn this common knowledge to the human species. Darwin didn’t.”

Dawkins deals meticulously, step by step, with common objections to evolutionary theory. E. g., “It is only a theory,” thus by implication not a fact. Scientists use, “theory,” as in the first definition in the venerable Oxford English Dictionary: “A hypothesis that has been confirmed or established by observation or experiment, and thus is propounded or accepted as accounting for the known facts….” In short, it is factual to the point of being beyond a reasonable doubt. The secondary definition of “theory” in the OED is, esssentially, “A speculation…an individual view or notion.” Creationists like this secondary defintion, though it is inappropriate in this usage.

This volume is enriched by pertinent line drawings, half tones, and color photos of fossils, of people, of flowers (e.g., that cunningly disguised spider orchid) and more. I was unable to read about the dancing sifaka, a lemur, without pausing to locate online videos of this charming creature dancing its way across a clearing in its native Madagascar. A well organized index and end notes add to the utility of this work. It is an entertaining and informative volume, well written and a good refresher course for the scientist as well as for the public at large.


Sifaka Lemurs

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