Does Intelligent Design Have Merit?

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Before Darwin, most of the educated world thought that the intricacies of biology pointed to a designer of life. And, as the medieval philosopher Thomas Aquinas would say, “by this we mean God.” In the early 1800s an Anglican clergyman by the name of William Paley wrote a widely read book which probably made the strongest case to date for design in nature. Darwin himself is said to have been deeply influenced by Paley’s work. However, after thinking about what he saw on his trip on the H.M.S. Beagle, Darwin proposed his theory of evolution by random variation (mutation) and natural selection. Briefly, Darwin saw that variation exists in species, and that not all animals that are born live to reproduce. So he reasoned that the organisms whose chance variation gave them an edge in the struggle to survive would leave more offspring who survived. If this process were repeated through many generations, Darwin thought, the species might change into something altogether different. Darwin and many scientists who followed him thought that his mechanism might mimic the appearance of design.

Well, that was the theory. But only recently has science been able to test that idea, as scientific progress revealed in the 20th century that life is based on complex cellular and molecular machinery unknown to Darwin and his contemporaries. Does random mutation plus natural selection build the sophisticated nanotechnology of the cell? In the early 1990s University of Michigan microbiologist Richard Lenski began the biggest in vitro evolution experiment in history, one that could potentially answer that question. With much effort over the course of two decades, Lenski and collaborators showed that when the bacterium E. coli was grown in his lab for tens of thousand of generations, with a population size of trillions of bacteria, many beneficial mutations were selected because they improved the ability of a microorganism to outcompete its siblings. Yet, when Lenski tracked down the mutations, they tended to be degradative changes, ones which destroyed genes or made them less efficient. That is not the sort of process one needs to build complex molecular systems.

Lenski’s results echo data from other organisms. For example, humans have acquired a number of helpful genetic changes in our battle with the malarial parasite over the past ten thousand years. The most well-known of these is the sickle cell mutation, which unfortunately can also lead to the lethal side effect of sickle cell disease. Other mutations that are helpful in the fight with malaria also degrade or destroy genes, such as globin genes and the genes for glucose-6-phosphate dehydrogenase, pyruvate kinase, Duffy antigen, and Band 3 protein.

Our best evidence shows that Darwin’s mechanism of random mutation and natural selection does not mimic design. Rather, like a bull in a china shop, random mutation tends to destroy delicate systems which, serendipitously, can occasionally help an organism survive in desperate circumstances.