Last autumn, the U.S. bishops had a workshop on the theory of evolution. Since the theory of evolution touches on the subject of man's origins, the Church has a deep interest in the matter. Pope John Paul II, in fact, has urged Catholics to avoid a fortress mentality when dealing with scientific evidence for the theory.

But the Pope also cautions about materialist philosophy disguised as science: “ The Church … distrusts only preconceived opinions that claim to be based on science, but which in reality surreptitiously cause science to depart from its domain.” There is no question that the writings of many Darwinists flunk this test. People like Stephen Jay Gould, Richard Dawkins, and Richard Lewontin will not do science without first putting on their philosophical blinders. Lewontin, who teaches genetics at Harvard, has said as much: “ We take the side of science … in spite of the tolerance of the scientific community for unsubstantiated just-so stories, because we have a prior commitment, a commitment to materialism.”

Unfortunately, the keynote speaker at the bishops' conference was just this sort of Darwinist. To compound the problem, his Darwinism is badly dated. In the keynote address, Francisco Ayala, who teaches biology at the University of California, presented to his audience a brand of neo-Darwinism which Stephen Jay Gould of Harvard long ago declared “dead, despite its persistence as textbook orthodoxy.” Ayala misrepresented the fossil record and gave the false impression that the genetic mechanism that turns one species into another is perfectly transparent to science. His presentation of Darwinism was full of the sort of philosophical additives about which the Pope was speaking.

Ayala used a favorite rhetorical device of Darwinists when addressing an audience of scientific laymen. He made no distinction between “Darwinism” and “evolution.” The idea of evolution, of the common descent of species, has been around since the ancient Greeks. St. Augustine was a kind of evolutionist, although hardly a Darwinist. What Darwin did was suggest a simple mechanism—natural selection—to explain how evolution had occurred.

Although you would never know it from reading Ayala's paper, it has long been clear that Darwin's mechanism is due for retirement. Neither the fossil record, nor breeding experiments, nor mathematical probability support the idea that small DNA copying errors “guided” by natural selection created everything from bacteria to human consciousness. Leaving aside the vexed question of how DNA assembled itself in the first place, a growing number of scientists think that Darwinian selection is a grossly inadequate mechanism for the creation of complex life forms.

In fact, natural selection doesn't create anything. It simply eliminates what doesn't work. As one biologist puts it, to say that natural selection does anything is a bit like answering the question, “Why are there leaves on the tree?” with, “Because the gardener did not cut them away.”

Ayala states that the absence of transitional forms in the fossil record has been “discredited.” But all he offers are “micro-evolutionary” examples. The fact is, there are systematic gaps between all major animal groups. A man from Mars looking at the fossil record of the last half billion years would say that species are replaced by other species, rather than evolve into them. Steven Stanley, a pale-ontologist who teaches at Johns Hopkins, writes in The New Evolutionary Time Table that, “the fossil record does not convincingly document a single transition from one species to another.”

Ayala's basic argument is that you can simply extrapolate major evolutionary changes from the small shifts that occur all the time within species. But scientists like Gould, Niles Eldredge, and the late Pierre Grasse argue that such extrapolation is inadmissible. All species appear to be “hard-edged.” They have enough genetic variability to cope with changes in their environment, but never go beyond certain barriers. Dogs remain dogs, fruit flies remain fruit flies.

Several years ago I had drinks with an evolutionary biologist who works at the Museum of Natural History in New York. I waited until he had had a couple of beers, and then said: “You say that Darwinism is dead, and you are obviously not a creationist. So, what do you believe?” His reply was honest: “Look, we know that species reproduce and that there are different species now than there were a hundred-million years ago. Everything else is propaganda.”

The origin of species remains a scientific mystery. The idea of the common descent of all species is perfectly plausible, but we have no idea how a batch of inorganic material morphed itself over billions of years into giraffes and chimpanzees. Man is a separate mystery altogether. The explanatory glibness of Ayala's paper glosses over many serious problems.

George Sim Johnston is a writer based in New York.