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From NPR News, it's ALL THINGS CONSIDERED. I'm Michele Norris.

The theory of evolution has always had its doubters. They say it's just not possible that humans are the product of natural processes alone. A higher power must have been involved. The doubters haven't gone away in the 150 years since Darwin published his theory, but they found a new focus - the human brain.

NPR's Jon Hamilton reports.

JON HAMILTON: Darwin skeptics have honed in on something called the mind-brain problem. It goes like this: How can the brain, which is just a bunch of cells, produce things like consciousness, subjective experience and free will? And how can these things be the result of evolution? Most brain scientists say there's plenty of evidence that things like consciousness have evolved along with the brain. Steven Novella is a neurologist at Yale University. He says our minds depend on our brains.

STEVEN NOVELLA: If you change the brain, you change the mind. If you damage the brain, you damage the mind. If you turn off the brain, you turn off the mind. And now, with more sophisticated tools - when we're looking at brain function with functional MRI, for example - we can see that brain activity precedes mental activities and that makes sense, because, you know, causes come before their effects.

HAMILTON: But Novella adds that scientists don't know how the brain causes the mind.

NOVELLA: We know that it does. The evidence that it does is overwhelming, just like we know that life evolved. But we're not sure exactly how and there's real debate going on about how science needs to further explore that question.

HAMILTON: And here's where the Darwin doubters come in. One of them is Michael Egnor from the State University of New York, Stony Brook.

MICHAEL EGNOR: I'm a neurosurgeon. I realize how closely the mind and the brain are related. But the question is, is there something else, in addition to the material properties of the brain, that we need to invoke to have an adequate explanation for the mind? And I think there is.

HAMILTON: Egnor says that something else is an intelligent designer that had a hand in producing not only the brain, but all living things and certain features of the universe. Egnor says without this designer, the brain would be just a meat computer made up of brain cells.

EGNOR: There is nothing about neurons that scientifically would lead you to infer consciousness from them. They're masses of gelatinous carbon, and hydrogen, and nitrogen and oxygen - just like other kinds of flesh. And why would flesh have first-person experience? So, even logically, it doesn't hang together.

HAMILTON: Egnor and Novella have been arguing about the mind-brain problem for months now on dueling blogs.

Egnor writes for a blog called "Evolution News and Views," hosted by the Discovery Institute. It's a think tank that's the hub of the intelligent design movement, which rejects Darwinian evolution. Novella writes for a blog called "Neurologica," hosted by the New England Skeptical Society. Neither has much respect for the other's ideas.

EGNOR: It struck me as being absurd.

NOVELLA: He has a script that he's following.

EGNOR: And of course, that's nonsense.

NOVELLA: Logical fallacies, poor reasoning.

HAMILTON: And so on. Novella, the Darwinist, says he's written several responses to Egnor's contention that brain cells alone can't cause the mind.

NOVELLA: The brain uses energy. It can hold information. It can communicate. It can receive sensory input. It could even activate itself and create a loop of ongoing activity. It could do things that can plausibly cause consciousness and self-awareness. So, the argument really just falls on its face.

HAMILTON: Novella also says Egnor is really a creationist who's recycling the religious arguments once used to attack evolution and the idea that natural selection could have produced our genetic code. Egnor agrees that some of the same arguments apply.

EGNOR: Whether it's the DNA code or whether it's the mind that understands the DNA code, both require an explanation that transcends what we know of matter.

HAMILTON: But he says he's not a creationist.

EGNOR: My personal view is that we have souls and that they're created by God, but you don't have to hold that view to recognize, what I think, is the evidence - that the mind is not entirely material.

HAMILTON: Not surprisingly, Egnor and Novella have very different views on the Terri Schiavo case. She's the woman in Florida who had severe brain damage and was taken off life support after a legal battle that lasted seven years. Novella says the court was right to assume that Schiavo's mind was determined by her physical brain.

NOVELLA: She had significant enough brain damage that it was incompatible with somebody being conscious in any significant way, and it's reasonable to base medical decisions on that scientific evidence. If you also want to bring moral or ethical things into the picture, that's slightly different. You know, science doesn't make moral decisions for us, it just informs our moral decisions.

HAMILTON: Egnor says the court was wrong because there's no scientific test that can detect the presence of a mind. And he says anecdotal evidence suggests that even when the brain stops working, the mind can persist. These anecdotes usually involve a person who has nearly died.

EGNOR: The person was able to have mental processes during a time when they were in cardiac arrest, in cardiac standstill and sometimes even with absent EEG waves. So, I think that there is very real scientific evidence that the mind, in some circumstances, can exist without a functioning brain.

HAMILTON: Darwinist brain scientists say in these cases the brain is still functioning, even if its electrical signals are hard to detect. For the record, Egnor and Novella do agree about one thing. The outcome of the mind-brain debate will have a profound impact on everything from what students learn in high school to how decisions are made at the end of life.

Jon Hamilton, NPR News.

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