WASHINGTON—At the heart of the argument over teaching evolution in the classroom is the claim that some scientists, not just religious believers, support the concept of "intelligent design."
Advocates of intelligent design argue that living things are too complex to be explained by natural forces alone. Therefore, they say, only a higher power—God or an unnamed "designer"—could create life and empower it to evolve into the myriad species of organisms on Earth today.
The vast majority of working scientists contend that biological evolution is an established fact supported by overwhelming evidence. They say that evolution's mechanism is well explained by the process of random mutation and natural selection that Charles Darwin described 147 years ago. Darwin's theory—updated and confirmed by recent genetic discoveries—eventually will answer all or most questions about the origin and history of life, they say.
Nevertheless, polls repeatedly have found that a majority of Americans accept the concept of intelligent design and want it to be taught in schools along with evolution. President Bush waded into the debate in August, saying that schools should teach both.
Several school districts across the country want design to be taught along with evolution in science classes. A federal judge in Harrisburg, Pa., this past week began hearing a lawsuit against the Dover, Pa., school board, which voted last fall to require students to learn about intelligent design.
The passionate public disputes over teaching design have focused attention on vigorous debates among scientists over specific pieces of evolutionary theory, which until now were largely confined to learned books and journals.
For example, scientists know how atoms and molecules combine to form larger structures and how primitive microbes evolved into fish, flowers, birds and people. But they admit that they don't understand the origin of life itself, the crucial step when a lifeless molecule became a living cell. There are many hypotheses, but no proven natural process.
"The big problem is making life," Edward Peltzer, an oceanographer at the Monterey Bay Aquarium Research Institute in California, told the Kansas Board of Education during a dispute over intelligent design in May.
One argument for intelligent design comes from Robert Kaita, a physicist at the Department of Energy's Princeton Plasma Physics Laboratory in Princeton, N.J. He noted that the world depends on a delicate balance among the precise properties of the universe, such as gravity, electromagnetic radiation and the forces inside the atom. The slightest change in the fine-tuning of these quantities would make life as we know it impossible.
"For me, they provide compelling evidence for a designer," Kaita said.
Mainstream scientists contend that there's no positive scientific evidence for intelligent design. They say the case for a supernatural designer is purely negative—an unjustified leap into theology to explain holes and uncertainties in evolutionary theory.
"The only evidence that intelligent design is able to muster is the observation that science has not yet explained everything, and therefore design must be kept around as a default explanation for what is left," said Kenneth Miller, a biologist at Brown University in Providence, R.I.
"There is exactly zero evidence for intelligent design," agreed Douglas Futuyma, a biologist at the State University of New York in Stony Brook. "Design advocates argue by claiming flaws or gaps in evolutionary knowledge or theory, not by any positive evidence whatever for their theory."
Nevertheless, supporters of intelligent design argue that their position is based on science, not just religious faith.
"We are challenging the philosophy of scientific materialism, not science itself," says a policy statement from the Discovery Institute in Seattle, the headquarters of the design movement.
Carl Koval, a chemist at the University of Colorado in Boulder, called intelligent design "a scientific objection" to the Darwinian theory of evolution. "There is nothing unscientific about saying that a theory doesn't fit with the observations," Koval said.
The design movement asserts that Darwinism is unable to explain not only the origin of life, but also gaps in the fossil record, the vast variety of modern body shapes, the complexity of a cell or the genetic information contained in DNA.
Intelligent design leaders take pains to distinguish their position from "creationism"—the belief, based on the biblical book of Genesis, that God created the Earth and its inhabitants in six days 6,000 years ago. Instead, design backers accept that the Earth is 4.5 billion years old, and that life is at least 3 billion years old.
They admit that evolution works on a small scale, "micro-evolution" within a single species, but assert that it cannot form entirely new species, known as "macro-evolution."
To buttress its case, the Discovery Institute has collected about 400 signatures on a statement labeled "Scientific Dissent from Darwinism." About 80 of the signers are biologists; the rest are mostly philosophers, mathematicians, chemists, computer scientists, historians and lawyers.
The statement of dissent, however, doesn't even mention intelligent design. Instead, it simply raises doubts about the present state of evolutionary theory. In its entirety, the statement reads:
"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."
"That statement is one that most scientists can or should be able to sign," said Martin Poenie, a cell biologist at the University of Texas in Austin, one of the signers.
Some who signed the statement of dissent said that doesn't mean they support intelligent design.
One signer, Stanley Salthe, a zoologist at the State University of New York in Binghamton, replied "absolutely not" when he was asked if he agrees that there must have been a supernatural designer.
David Berlinski, a mathematician and senior fellow of the Discovery Institute's Center for Science and Culture and a sharp critic of neo-Darwinism, also signed the statement of dissent. But in an e-mail message, Berlinski declared, "I have never endorsed intelligent design."
Asked to cite scientific evidence for supernatural design, John Marburger, President Bush's science adviser, replied: "There isn't any. ... Intelligent design is not a scientific concept."
Following are three of the reasons some scientists offer for intelligent design:
A basic text of the intelligent design movement is "Darwin's Black Box," published in 1996 by Michael Behe, a biochemist at Lehigh University in Bethlehem, Pa. Behe argues that living cells are far too complex to be explained by Darwinian evolution.
He calls this the problem of "irreducible complexity" and says it led him to conclude that cells must have been designed by an intelligent agent. He leaves it to his readers to decide whether the designer is God.
"Many systems in the cell show signs of purposeful intelligent design," Behe told the Kansas Board of Education in May. "What science has discovered in the cell in the past 50 years is poorly explained by a gradual theory such as Darwin's."
Besides cells, Behe says many other biological systems are too complex to evolve naturally—for example, the little propellers (flagella) that enable bacteria to swim, the blood-clotting mechanism and the immune system.
"Not all things can occur by tiny, tiny changes ... leading to more complex systems," as neo-Darwinism proposes, he says.
"The notion of irreducible complexity is nonsense," Miller, the Brown University biologist, responded in his 1999 book, "Finding Darwin's God."
"The mechanism of evolution is real, is observable and is more than adequate to the task," Miller said. "Evolution tinkers, improvises and cobbles together new organs out of old parts."
For example, he said, bacterial flagella evolved from simple tubes used by microbes to inject poisons into other cells. Jawless fish had a primitive blood-clotting system that grew more complicated in fish with jaws and still more complicated in advanced land animals.
"An irreducibly complex system can be built gradually by adding parts, which, while initially just advantageous, become essential," said Allen Orr, a biologist at Rochester University in Rochester, N.Y.
_ THE CAMBRIAN EXPLOSION:
A key argument from the intelligent design camp is that Darwinian evolution can't explain the so-called Cambrian Explosion, an astounding blossoming of animal life around 530 million years ago.
The event is sometimes known as "Evolution's Big Bang," when major new groups of animals—including shellfish, insects and creatures with spinal cords, the ancestors of fish, reptiles and mammals—spread rapidly over the Earth.
"The Cambrian explosion occurred within an exceedingly narrow window of geologic time, lasting no more than 5 million years," said Stephen Meyer, a philosopher of science and a senior fellow of the Discovery Institute.
Intelligent design advocates say the sudden appearance of so many new major body types (called phyla), couldn't have arisen by slow, gradual steps, as Darwin's theory assumes. They say the fossil record lacks transitional stages connecting complex Cambrian creatures with older, simpler living forms.
"The Cambrian fossil record contradicts" the Darwinists' expectations, Meyer said.
"To suddenly appear in the Cambrian must remain inexplicable," said Jonathan Wells, another senior fellow at the Discovery Institute who holds doctorates in religion and biology. "Clearly, Darwin's theory of life does not fit the fossil evidence for the origin of the major groups of animals."
Mainstream biologists, however, insist that Darwinian evolution can explain the rise of new phyla and species. They say the Cambrian explosion wasn't as abrupt or as inexplicable as the design movement contends.
New evidence shows that relatively complex animals existed as many as 125 million years before the Cambrian period. Fossil embryos 40 million to 55 million years before the Cambrian have recently been discovered in southern China.
Recent studies of DNA sequences in well-dated fossils "set the divergences of these major groups to a time well before the Cambrian," Andrew Cameron, a biologist at the California Institute of Technology in Pasadena, reported in the journal Science last year.
"As the fossil record becomes more complete, it sometimes provides the very intermediate forms the nonexistence of which the creationists were willing to predict," Miller said. "Even their favorite gaps are filling up, and the historical record of evolution becomes more compelling with each passing season."
_ THE ORIGIN OF LIFE
Scientists associated with the design movement claim support for their theory from the fact that mainstream Darwinists cannot tell how life began. There are many hypotheses, but no consensus, on how lifeless molecules became living cells.
Every laboratory experiment to "produce some of the simplest chemicals of life has completely failed," said William Harris, a biochemist at the University of Missouri in Kansas City. "The information carried in DNA cannot be explained by the laws of physics and chemistry."
In response, Robert Hazen, a geologist at the Carnegie Institution of Washington, said, "We don't have all the answers right now, but there is no evidence that the origin of life is other than a natural process."
In his new book, "Genesis: The Scientific Quest for Life's Origin," Hazen recounted a host of experiments that attempt to show how chemical evolution might have produced a primitive "proto-cell" from complex organic molecules that were readily available on the early Earth. After that beginning, he said, the cells could have gradually evolved into the enormous range of organisms inhabiting the planet.
Although no one has created life in the laboratory yet, Hazen predicted that someone is likely to succeed in the next 10 to 20 years. That may not be the way it actually happened, but such an experiment would show that life could be created without divine intervention.
For more information from the intelligent design camp, go to the Discovery Institute at http://www.discovery.org
For more from critics of intelligent design, go to the National Center for Science Education at http://www.natcenscied.org
(c) 2005, Knight Ridder/Tribune Information Services.
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