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Evolution: It’s all in the definition!

Bob Brustman had an intriguing and thoughtful piece recently in the Harvard University Gazette entitled “Evolving Ideas” which investigates why many people are skeptical of evolution.

He starts off describing a simple but ultimately inadequate argument from Richard Lewontin:

“If you believe in atomic energy, he said, then you believe in rates of decay. If you believe in rates of decay, then you believe in radiation dating. If you believe in radiation dating, then you believe that we can identify strata of rock from different times.

Those strata of rock contain fossil evidence of plants and animals. Different strata of rock contain different types of fossils, yet each fossilized plant or animal had parents. Therefore, at some point, a parent life form must have given birth to progeny that were different from the parent. If you accept all of this, then, voila! You believe in evolution.”

I have no objections to any of that logic. But the question is, what do we mean by “evolution” when we arrive at it as our conclusion?

Typically, “evolution” can have one of three possible meanings:

  • (1) Change over time

  • (2) All organisms share a common ancestor

  • (3) Random mutation coupled with blind natural selection was the primary agent of that change with common descent.

Eugenie Scott seems to concur with this view as she outlines the meanings of evolution in her Declaration in the Hurst v. Newman case:

“Evolution,” broadly defined, is “a cumulative change through time.” It refers to the fact that the universe has had a history — that if we were able to go back in time, we would find different stars, galaxies, and planets, and different forms of life on Earth.


In biology, evolution is the claim that living things share common ancestors and have, in Darwin’s words, “descended with modification” from these ancestors. The main — but not the only — mechanism of biological evolution is natural selection.

(Hurst v. Newman, Declaration of Eugenie C. Scott in Support of Plaintiffs…)

It is the third definition — as Scott puts it “The main — but not the only — mechanism of biological evolution is natural selection” — that educators are aiming for. Brustman quotes Harvard professor Richard Wrangham stating that this should be an easy sell if one’s mind is “open:”

“The case for evolution by natural selection is so strong that if you have people with open minds, it’s easy.”

Apparently the more than 500 scientists who agree with this statement simply don’t have “open minds”:

“We are skeptical of claims for the ability of random mutation and natural selection to account for the complexity of life. Careful examination of the evidence for Darwinian theory should be encouraged.”

And perhaps eminent biologist Lynn Margulis, a deeply committed evolutionist who believes that symbiogenesis drove much evolutionary change and that natural selection does not generate real novelty, also has a closed mind. Margulis and Sagan write:

“We agree that very few potential offspring ever survive to reproduce and that populations do change through time, and that therefore natural selection is of critical importance to the evolutionary process. But this Darwinian claim to explain all of evolution is a popular half-truth whose lack of explicative power is compensated for only by the religious ferocity of its rhetoric. Although random mutations influenced the course of evolution, their influence was mainly by loss, alteration, and refinement. One mutation confers resistance to malaria but also makes happy blood cells into the deficient oxygen carriers of sickle cell anemics. Another converts a gorgeous newborn into a cystic fibrosis patient or a victim of early onset diabetes. One mutation causes a flighty red-eyed fruit fly to fail to take wing. Never, however, did that one mutation make a wing, a fruit, a woody stem, or a claw appear. Mutations, in summary, tend to induce sickness, death, or deficiencies. No evidence in the vast literature of heredity changes shows unambiguous evidence that random mutation itself, even with geographical isolation of populations, leads to speciation. Then how do new species come into being? How do cauliflowers descend from tiny, wild Mediterranean cabbagelike plants, or pigs from wild boars?”

(Lynn Margulis, Dorion Sagan, Acquiring Genomes: A Theory of the Origins of the Species, pg. 29 (Basic Books, 2003))

A final intriguing quote in the article comes from Professor Wrangham on how the successful teaching of evolution is dependent upon showing people how evolution and religion are compatible:

“Wrangham admitted that religion and the teaching of evolution sometimes bumped heads. He said, “The reason so many people do not believe in evolution is surely because they had very strong religious beliefs first … and if we are going to teach evolution successfully, we have to find a way to marry those two things.”

In Wrangham’s analysis, we simply have to open people’s minds to evolution by natural selection by changing their religious beliefs about evolution, and then all the skepticism will disappear. Let’s reiterate: Wrangham said, “if we are going to teach evolution successfully, we have to find a way to marry [evolution and religion].” At least now it is out-in-the-open: these evolutionists have an agenda to “find a way” to change people’s religious beliefs about evolution.

Will they be successful in erasing skepticism? Evolutionists have been trying to modify people’s religious beliefs about evolution for decades, but the public remains skeptical.

Perhaps there’s more in the objections to evolution than mere religion.

Ultimately, it seems that growing scientific skepticism over evolution by natural selection means that Wrangham will have to “find a way to marry” evolution (3rd definition), and the empirical data. Meanwhile, some of us who have been following this debate for a while may feel justified in giving up on waiting for the wedding invitation.