In 1859, Charles Darwin published On the Origin of Species, laying forth exhaustive evidence that all living things are descended from a single common ancestor.
In 1999, the Kansas Board of Education voted to delete most references to evolution from the biology curriculum. But in last August's Republican primary voters replaced three conservative candidates who supported that decision with candidates who pledged to return evolution to the curriculum.
Why all the fuss? Because we can't fight disease, we can't protect our food supply, and we can't understand ourselves without understanding evolution.
Physicians treated tuberculosis with isoniazid and rifampin for years, but some strains of bacteria evolved resistance to them. Doctors now use principles of evolutionary biology to design treatments that prevent the microbes causing tuberculosis, AIDS, malaria, gonorrhea, and bubonic plague from evolving resistance.
Crop breeders mimic the process of natural selection to enhance the quantity and quality of our food. Crop breeding already adds more than $1 billion a year to the value of agricultural production, and it could add much more. But only if genes coding for valuable traits can be found in nature's library.
Evolutionary biology provides the card catalog, pointing to species with characteristics likely to be similar to those already known and to those that with valuable characteristics yet to be tapped.
Evolutionary biology also helps us understand periods of history for which there is no written record. Linguists argue, for example, that the resemblance among French, German, Russian, Greek, Latin, English, and other Indo-European languages is a result of the shared history of the peoples speaking those languages. Patterns of genetic variation suggest that this history dates from 8,000-10,000 years ago, when farmers replaced hunter-gatherers in Europe.
But what about creationism? Isn't it a reasonable alternative to evolution? Shouldn't it be given equal time in school?
Scientific hypotheses are tested and often found wanting. Nineteenth-century scientists studied the shape of the skull in hopes that it would provide a guide to character and intelligence. They were wrong. Scientists rejected creationism for similar reasons.
A creationist cannot explain why a mouse and a giraffe should both have seven vertebrae in their necks. A creationist cannot explain why the embryos of blue whales and anteaters grow teeth only to resorb them before birth.
An evolutionist explains both facts easily. Mice and giraffes have seven vertebrae in their necks because their common ancestor had seven neck vertebrae. The embryos of blue whales and anteaters have teeth because both blue whales and anteaters are descended from ancestors that had teeth.
An evolutionist can also make predictions that a creationist might never consider. An evolutionist can predict that the proteins of mice and giraffes will be more similar to one another than either is to those of a goose—and he would be right. He could even predict that the proteins of fish will be more different still and be right again.
Creationists sometimes claim that evolution violates the Second Law of Thermodynamics, which says that any system not receiving inputs of energy tends to become less ordered. But life and the earth receive energy from the sun, so the Second Law isn't violated. We use the sun's energy to produce order ourselves, in the petroleum that powers our factories and in the food that powers our bodies.
Science uses natural causes to explain natural phenomena. It explains diseases with microbes or physiological disorders, not with evil spirits. The search for natural causes of natural phenomena has allowed us to eradicate smallpox, to treat bacterial diseases, and to increase food production more than four-fold, all in the last seventy-five years.
Evolution is part and parcel of a scientific understanding of the world. Creationism is not.
Note: This piece first appeared in The Hartford Courant on Sunday, 7 January 2001.