The Origin of Species

Darwin was not the first to notice that biological systems show exquisite adaptation to their circumstances, in contrast to the random and chaotic nature of the inanimate world. Moreover, they appear to be designed with an exquisite precision that the best craftsmen then or now cannot emulate. Man, the designer and builder, made the natural assumption that a more subtle mind and hand was behind what Richard Dawkins has called “the almost perfect illusion of design” in the biological world.

Living systems presented another conundrum as well. There are strong analogies between different life forms, and those analogies form an organized hierarchy. It proved possible to organize living things in rather strictly hierarchical categories – dogs, wolves, coyotes and foxes were all clearly more like each other than any of them were like cats, say. Dogs, cats, and even bats and whales were more like each other than any of them was like a fish or a bird.

Intelligent design offered little insight into this, unless the Designer was a bit compulsive, but the notion of evolution seemed to offer some possibilities. An early try in this direction was Lamarck’s idea of descent with modification. Unfortunately for it, it didn’t fit the facts very well.

Darwin’s genius was to see that both these puzzles and much else could be understood through natural selection. I don’t think it is an accident that Darwin’s book was not called The Theory of Evolution or even The Theory of Natural Selection. The supreme advantage of Darwin’s theory over Intelligent Design was that it had explanatory power where ID had none.

Natural selection explains the hierarchy of life. Darwin saw that, and that, I think, is why he called his book The Origin of Species. One key element of Darwin’s story was the finches of the Galapagos islands. These birds were clearly related to mainland finches but had just as clearly differentiated to fill various ecological niches in the Galapagos that other birds filled on the mainland. Darwin knew the islands were relatively young geologically and distant enough from the mainland to make it difficult for birds to reach the islands from it. Here was clear evidence of selective pressures leading toward differentiation into various species. There is no simple way to fit this part of the story into intelligent design.

There are many other things that can’t be accounted for by intelligent design. Aside from cancer and other diseases which show either reckless or malevolent design, there are all the evolutionary kludges that we see. Why are our eyes wired backwards (like having a TV with the cable and power cord emerging from the middle of the screen)? Why are our heads screwed on backwards? There are a million other similar kludges that show the accumulation of consecutive undirected changes rather than intelligent design.

The replacement of the idea of intelligent design by natural selection is probably the greatest example of a paradigm shift in our understanding of the universe. That’s one reason I see no particular reason for not teaching ID, provided that the arguments against it are clearly and cogently presented. It’s only by considering such case studies that one can understand the power and breadth of Darwin’s Dangerous Idea, as Daniel Dennett has styled it.

Darwin’s greatest triumph is that this idea, published one hundred years before molecular biology was invented, can only be seen in its full power through the mechanisms of molecular biology. The world has now seen 150 years of discoveries that might have invalidated Darwin since, but instead they all reinforce his insights.