Friday, March 27, 2009

Why Evolution is True

The following argument is one that I imagine biologists must be very tired of making. I truly hope that I might see a day when it will no longer be necessary to say the following:

How difficult is it to convincingly present the evidence for biological evolution, and to display the failure of the "intelligent design" case in comparison? Piece of cake. Evidence exists from fossils, biogeography, and embryology. We have seen new species formed by natural selection both in the fossil record and in real time. We can see vestigial structures such as the human appendix, poor organization, and dead genes. If there were a designer, this might be considered evidence for gross incompetence.

Evolutionary theory makes testable predictions. For example, biologists can predict where, in place and period, fossils will be found. Or they can confidently make very specific claims such as: if an animal species has brightly coloured males and drab females, it will have a polygonous mating system.

Furthermore, DNA sequencing supports the evolutionary relationships of species originally deduced from EVERY fossil that we have found. Every DNA molecule that we sequence, every organ system that we dissect supports the idea that species evolved from common ancestors. And what we don’t find also provides support. We don't find mammals in Precambrian rocks, humans in the same layers as dinosaurs, or any other fossils out of evolutionary order.

We can show that the mechanism of adaptation is indeed sufficient for the emergence of complexity from simpler elements. For example, in the case of eyes, starting with the light-sensitive pigments seen in flatworms and going through the increasingly more sophisticated versions of precursor eyes respectively in limpets, the chambered nautilus, ragworms, abalones, and so upward - we can show show how every stage of the process confers some evolutionary advantage in the way of finding food, avoiding predators, and/or reproduction. The process required huge lengths of time and the billions of failures, but it did happen.

Religious efforts to derail biological enquiry waste time and energy. How credible are religious claims? How much influence should religious viewpoints have in the public square? What should be the relation between religion and science? These are all issues on which we just can't seem to agree.

Can religion and science not speak different kinds of truth? Creationists (as "intelligent design" theorists) squarely treat religion and science as direct competitors for the truth. They claim that "irreducibly complex" natural phenomena can only be explained by invoking a designer. “We don't understand this so let's say God did it.” If one cannot see how some complex thing came to be, it is not better to keep looking for the explanation, or even to accept the one does not know the answer, than to take the quick-fix of claiming that God did it?

Science starts with no prejudices, but is open and self-critical. It is the enterprise that seeks to understand and is always stands ready to revise itself in the face of contrary evidence. It is a good process. And it does not try to prove that there is no God. Science and atheism are not mutually inclusive.

Understanding technical science, especially the mathematics of it, is difficult. But can any responsible person claim complete ignorance about what many consider humanity's greatest achievement? Are there any good excuses for a lack of fundamental understanding physics, cosmology or biology with countless good books on the shelves? Nope. And might I suggest: "Why Evolution is True" by Jerry Coyne.

(I must give credit for this post to A.C. Grayling at Barnes and Noble dot com who reviewed Jerry Coyne's book. I have rearranged and simplified Mr. Grayling's words at my discretion but most of them are still very much his.)

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