Monkey business: Why intelligent design is weird science
Francisco J. Ayala, a professor of evolutionary biology and philosophy at the University of California-Irvine, is both an expert in the field of evolution and its ardent defender.
From serving as an expert witness in court battles over the teaching of evolution in public schools to writing a letter defending evolution to Pope Benedict XVI just last year, Ayala has been a tireless advocate of what he calls the "fact" of evolution, arguing strongly against the theory of intelligent design, whose advocates claim that evolution leaves no room for God.
But evolution and religion need not be adversaries, says Ayala. "Science can neither endorse nor reject religious beliefs," he writes in his book Darwin and Intelligent Design (Fortress), arguing that "we may accept [evolution] without denying the existence of God or God's presence in the universe." Ayala, winner of a 2001 National Medal of Science, has his work cut out for him: A June USA Today/Gallup survey of 1,003 adults found that two thirds of those polled believe that humans were created by God about 10,000 years ago, while only 52 percent say that humans evolved over millions of years.
When scientists talk about the theory of evolution, what do they mean?
Evolution is the history of living things, the origin and development of life. We used to study it by means of morphology, paleontology, and fossils, but now we also use DNA because it has much more information. With DNA we can now ascertain the evolutionary history of an organism. We can now trace the history of living organisms all the way back to a single universal common ancestor.
Evolutionary theory also includes the mechanisms by which evolution operates. The key process is natural selection, which accounts for adaptation. Natural selection is one of the greatest discoveries in the history of science. It is the process that explains why we have eyes for seeing, hands for grasping, legs for walking.
The evidence for evolution is so strong that we often speak of it as the "fact" of evolution. It is no longer an issue that occupies scientists nowadays, because the fact that evolution has occurred and accounts for the history of organisms is certain, just as science is certain that the Earth revolves around the sun.
When scientists refer to evolution as a theory, does that mean it might not be true?
Theory in science does not mean unsupported opinion but rather a well-established body of knowledge, which includes concepts and explanations that have been tested by scientific method. When scientists refer to what is called a theory in common language, they call it a hypothesis, an assumption or guess that has yet to be fully tested. But the word theory is never used in science to suggest something like a hunch.
How can scientists be so certain about the "fact" of evolution?
As you may have read in the papers or seen on television, we can use DNA to find out the identity of the father of Anna Nicole Smith's daughter. Most people know about convicted prisoners whom DNA has proved innocent.
By looking at DNA we can also reconstruct the history of evolution because DNA carries all the genetic information of living organisms. DNA changes gradually over time through mutations, which are fairly rare. Natural selection determines which of those mutations are beneficial and become established, and which ones are eliminated.
DNA has an enormous amount of information. We inherit 3 billion nucleotides (bits of DNA each signified by one letter) from each one of our parents, what we call one genome. The letters that make up one human genome alone would fill about a thousand volumes the size of a Bible. So there's a lot of information to compare organisms with each other, which allows us to reconstruct their evolutionary history. We can keep studying more DNA until we get greater and greater precision. That is, by comparing the DNA of species we find out how species are related. For example, we now know that chimpanzees are more closely related to humans than chimpanzees are related to gorillas or orangutans. We know that just by looking at the number of differences in the DNA for each of the species.
How is the theory of intelligent design different from evolution?
Proponents of intelligent design say that organisms are so complicated, so complex, that, first, they give evidence of having been designed by an "intelligent designer," a sort of engineer, and, second, they could not have come about by chance.
Now the first part about the engineer is wrong; the second part is actually right. Organisms could not have come about by chance. The components that make up an eye could not have been put together by chance.
Natural selection is not chance. It's a process that selects what is useful to the organism and thus preserves the changes that "make sense" for its survival.
Where does intelligent design come from?
The argument "from design" was the fifth way that Thomas Aquinas used as proof for the existence of God: that there is clearly purpose and direction, a harmonious design all through the universe, that reflects a knowledge and intelligence, which we call God. The argument was developed by the Greeks well before the Christian era. And it was certainly used by some in the early church.
In the context of biology, the argument was articulated by William Paley, a distinguished theologian and clergyman in the second part of the 18th century in England. In an important book called Natural Theology, he develops the argument in great detail. The argument has two parts: first, there is design in nature; and second, only God could have been the designer.
Paley looks at the eye for example, pointing out that it has the only black tissue in the body, the retina, which is placed in the exact position where rays of light can converge and an image can be formed. Paley sees the whole series of precise relationships between the parts of the eye as proof of design.
He goes on to look at all the organs, at the differentiation between the sexes, and so on, giving evidence that everything is designed very precisely.
Paley does admit in one chapter that there are defects in the design of organisms. He says that even if we find defects and imperfections, we should ignore them because of the abundance of perfection and design. But if God has to account for everything, you cannot get away by just saying that the defects are insignificant. Paley was at least honest enough to bring up the point.
How did intelligent design work its way into our public debate?
In terms of recent history, in 1967 the U.S. Supreme Court declared unconstitutional laws that prohibited the teaching of evolution in public schools, at which point something called "creation science" was invented. Some laws then demanded that biology teachers give equal time to creation science and evolutionary theory, even though the six principles of creation science were taken out of Genesis. If teachers didn't want to teach creation science, then by law they could not teach the theory of evolution either. In 1986 the Supreme Court said that creation science is not science but religion, and therefore could not be taught in the schools.
So in the 1990s some began reviving Paley's arguments as "intelligent design," which in terms of modern biology really does not make any sense. There is only one biologist, a professor at Lehigh University named Michael Behe, who has tried to develop this argument by pointing out complex designs like the flagellum of some bacteria, which allows them to swim, or the blood-clotting mechanism in mammals.
But even Behe himself points out that the clotting mechanism is so unnecessarily complicated that it could have been designed better by a human. God is evidently so clumsy that he created something complicated to accomplish something simple.
That's the way evolution works many times, but not God. A human engineer would have done better.
How does Behe account for the inefficiency?
Behe admits that organisms evolve but argues that from time to time God has to intervene to create the parts that are too complex. So God has to fix something from time to time to perfect it. But there is no scientific validity to that.
In science we articulate a hypothesis and develop experiments to test it. How can you test intelligent design? There is nothing that can be tested. There are no experiments, no scientific explanations; nothing has been done to support this theory. Its proponents just assume that the complexity of evolution cannot be explained by natural processes.
Are the problems with intelligent design just scientific?
From my point of view intelligent design is blasphemy. There are not only imperfections, as Paley noticed, there are outright dysfunctions and an enormous amount of cruelty and sadism in evolution. You wouldn't want to attribute that to the Creator. Almost nothing is well designed.
Take the human jaw: It is not big enough for our teeth, so we have to pull out the wisdom teeth and then straighten the others. An engineer who designed a jaw not big enough for all the teeth would be fired.
The human eye has a huge defect because the way the eye evolved in mammals left a blind spot where the optic nerve crosses the retina on the way to the brain. Octopus and squid, on the other hand, have eyes as complex as ours, but without a blind spot. What a mistake to attribute to the Lord!
We have known for some time that 20 percent of all pregnancies end in spontaneous abortion within the first two months, about 20 million miscarriages a year. If God explicitly designed the human reproductive system, is God the biggest abortionist of them all? Even the human birth canal isn't big enough for the babies. Roughly 530,000 women die each year as a consequence of pregnancy and childbirth. There's something very wrong there.
Does evolution do any better in accounting for these problems?
The natural sciences explain why we have day and night and why there are storms and tsunamis. We understand these as natural phenomena, so we don't have to assume that God wanted to kill 200,000 people somewhere in Indonesia.
In the same way, Darwin, by discovering natural selection, helps us understand why there are deficiencies and defects caused by evolution, so we don't have to see them as a result of the action of God.
Granting that evolution is part of the created world, how do you square the cruelty of the process with the idea of a benevolent God?
One way is to ask: Who are we to tell God what kind of world should have been created? Think of moral evil, the kind created by human action, and the tradition of explaining it in Christian theology. Why does God allow moral evil in the world? We say, well, it's free will, and we have to pay a price for that. You cannot be virtuous unless you have freedom, which leaves open the possibility of evil and sin.
The same with life. It's a dynamic world that is changing, and some bad things can happen. We can judge by our moral standards the cruelty of the lion or of parasites, whose only purpose is to destroy their host. But God created a world where evil could appear, both moral evil and physical evil, and biological evil as well, if you want to call these evolutionary deficiencies evil.
Why didn't God create the world in a different way so that evil does not exist? How do you read the mind of God?
What is the position of the Catholic Church on evolution?
The encyclical Humani Generis by Pope Pius XII in 1950 was the first positive Catholic statement on evolution (see sidebar), but more recently Pope John Paul II produced a very articulate statement, which he addressed to the Pontifical Academy of Sciences in 1996. In it he said that evolution is no longer just a hypothesis but is well proven, with evidence coming from many different disciplines. We are not looking for more evidence to prove evolution because additional proof is not necessary, and John Paul is very explicit about it.
Of course he asserts, as did Humani Generis, that the human soul could not have come about by evolution. Anything that is spiritual could not have come by evolution from material things, so you have to come up with other explanations to explain the soul.
But didn't Cardinal Christoph Schönborn of Vienna publish an article in The New York Times questioning evolution a few years ago?
He did, but I think he was taken advantage of. It turns out the vice president of the Discovery Institute in Seattle, an intelligent design think tank, is a friend of Schönborn. He persuaded the cardinal to write about intelligent design, and the institute's public relations firm sent the article to The New York Times.
Within a month after it broke, three of us wrote a letter to the pope: a Catholic biologist named Kenneth Miller, who had written a wonderful book on the subject; a physicist named Lawrence M. Krauss; and me. We suggested there would be severe consequences for the Catholic Church in relation to science if Schönborn's piece were allowed to stand.
Within a month Schönborn essentially retracted the article in a speech at one of the Catholic universities in Vienna. He put his talk, in German, on his website. Of course not too many people here are likely to read long speeches in German. Then he issued a statement to the press saying that he was misunderstood and what he meant is not what he actually said.
Pope Benedict has an annual seminar for his former students; in the summer of 2006 they discussed evolution and design. The report that I have of it is from one of the attendees, the current president of the Academy of Sciences in Vienna, whom I've known for years. He gave a lecture on certain questions concerning evolution, and there were no objections raised.
Are there those on the scientific side who are just as hostile to religion as some believers are to science?
Richard Dawkins is one example; I have known him well for many years, and I consider him a friend. He's a great popularizer of evolutionary theory, and I have endorsed his works. But he also, as reflected in his last book, The God Delusion (Houghton Mifflin), has a strong animus against religion.
He often talks as if religion is the source of all evil. There's no question that bad things have been done in the name of religion, but bad things have been done in the name of science as well, like sterilizing people or using people as guinea pigs for experiments.
Dawkins and others hope and expect that in a few decades religion will vanish from the world, though it's utterly inconceivable to me that something like that could happen.
Could science fill the vacuum that would be left if religion vanished?
Science has nothing to say by itself about values. We cannot derive our values from science. Science could not have produced the Ten Commandants or any of the other moral texts of the great religious traditions.
Science cannot give meaning to life. Even if the 6 billion people in the world universally accepted the principles and concepts of science, they would have to find values, meaning, and purpose somewhere else.
Is there anything else evolution can't account for?
There has been controversy about morality. One school of thought says morality is driven by genes. It's obvious in the case of what is called kin selection, the way relatives behave with each other. Since my brother has 50 percent of his genes in common with me, if I fight for my brother, I'm defending my genes. Most philosophers of ethics, however, say that morality is a cultural construct, not an evolutionary, biological one.
My own view is that we are moral beings because of our biology, but our moral systems are cultural constructs. Because of our big brains, we cannot help but anticipate the consequences of our actions with respect to other people, which is where morality is involved.
But there are obviously cultural and historical differences in moral systems. Some systems, like those of the great religions in general, have been very successful. But our moral systems have to be consistent with our biology, or we will not survive.
Is the conflict or dialogue between science and religion something that's new, or is there a longer history?
The best place for me to start is about the year 400, when St. Augustine published his commentary on the Book of Genesis. There, and later in his Confessions and City of God, he says that there is human knowledge and there is faith, science, and revelation to use modern terms. Augustine says that when scripture contradicts well-established human knowledge, then scripture is being misinterpreted.
Thomas Aquinas in one of his major works, the Summa Contra Gentiles, also identifies two sources of truth. One is revelation and the other is reason, and they deal with different kinds of truths.
At the time Aquinas was teaching, the prevailing thought was that revelation and reason could say contradictory things. But Aquinas said that truth cannot war with truth. The Trinity and the Incarnation come from revelation, and knowledge of the natural world comes through reason. There is no conflict between the two.
Do you think that science and religion have wisdom that they can share with one another?
The process that has produced human beings and butterflies can certainly be an immense source of religious inspiration. Theologians like John Haught, who is Catholic, and the late Arthur Peacocke, who was Anglican, have drawn on scientific knowledge and evolution in particular to develop their own theology. I think we could use another Thomas Aquinas now.