Why Evolution Is Misunderstood - Evolution News & Views

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Why Evolution Is Misunderstood

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Recently, University of Chicago biologist Jerry Coyne embarked on a "BBQ, Evolution, and Atheism" speaking tour of the Southeast. At one of his stops along the way, a friend and I attended the event, a talk on "Why Evolution Is True (But Not Many People Accept it)." We found Coyne in a lecture hall packed with biologists, "brothers and sisters," to whom he imparted pastorly assurance as he recited the evolutionary creed. Coyne appeared to assume that all present shared his dismay at the shameful state of the unbelievers, blinded by faith in God instead of in Darwin, unyielding to the forces of change and the latest scientific discoveries.

If he understood the meeting as a gathering of the faithful, however, then he might have been upset to learn that among the biologists in the room there was, in fact, no firm consensus on Darwinian theory. His vehement intensity was also confusing. In Coyne's view there is evidently a dire need for the world to accept the predominance of Darwinian evolution as fact, but it was unclear why this is so urgently important. If unbelievers fail to shed their ungodly faith in God right away, what imminent disaster awaits? By the end of the presentation, my friend and I were still unsure.

There are many aspects of evolutionary theory. Darwin was responsible for one major hypothesis: that most evolutionary change is due to natural selection. The idea is that the differences between organisms are the result of mutations that have conferred reproductive benefits to their carriers, thereby spreading through populations, one after another. Coyne's strategy is to seize on this one contention, but then try to support it by gathering evidence for all the other aspects of evolution -- including genetic change over time, common ancestry, and speciation. He equates the entire theory with the Darwinian component, which was devised before genetics. While this may reflect a popular understanding of evolution, it is profoundly in error.

Consider the evolution of humans and chimps from a common ancestor, to which Coyne in his talk referred several times. Rather than offering evidence for such common ancestry, Coyne simply took it as a fact and then used it to support Darwinian selection. Yet the ubiquity of selection in creating these species makes little sense at the level of DNA -- the very level at which heritable change (evolution) occurs. By current estimates, the genomes of these two species differ by at least 300 million nucleotides. Given the premise that humans and chimps shared a common ancestor 6 million years ago, such a degree of divergence can only be accounted for by an average of 25 nucleotide changes per year in each line of descent.

For Coyne's gradual version of the Darwinian mechanism to account for these differences, 25 new mutations would have to appear, conferring a reproductive advantage, and spread through each population every year. Yet even 25 advantageous substitutions per generation is unfathomable. A similar problem prompted Motoo Kimura in 1968 to propose the neutral theory of molecular evolution. By assuming the selective neutrality of most mutations, the neutral theory seeks to explain how the number of evolutionary substitutions per generation may be as high as the mutation rate. Much evolutionary change is not Darwinian; it cannot be. Instead, the vast majority of this change more realistically involves selectively neutral mutations that drift randomly until they saturate a population's genome.

But Coyne's error runs even deeper. Natural selection, he claimed, is the only evolutionary process producing adaptation. But this is demonstrably false. In his 2007 book The Origins of Genome Architecture, Michael Lynch shows that many adaptive features of the human genome could not have arisen unless natural selection was first relaxed. The "myth that all of evolution can be explained by adaptation continues to be perpetuated by our continued homage to Darwin's treatise in the popular literature," he writes in PNAS.

However, Lynch continues, "It is difficult to reject the hypothesis that incremental expansions of eukaryotic gene complexity were largely driven by nonadaptive [i.e., non-Darwinian] processes." In other words, many features that are now advantageous were brought about by random processes. Stephen Jay Gould's exaptations, referring to organisms being pre-adapted to environments not yet encountered, are another example. The plasticity-relaxation-mutation model proposed by Austin L. Hughes is yet another. Coyne's talk even ignored the work of several scientists from his own university, including James Shapiro and Wen-Hsiung Li.

As Lynch writes, the "agenda to spread the word on the awesome power of natural selection has been quite successful, but it has come at the expense of reference to any other mechanisms, a view that is in some ways profoundly misleading." It's surprising to find that someone like Coyne who is so passionate about teaching evolution is also so unfamiliar with the current state of the discipline -- or else unwilling to accurately represent it.

Instead of adhering to the scientific evidence, and clearly delineating the different components of evolution, Coyne displayed an ignorance that brings shame to the scientific community and its pursuit of truth. His credibility is completely undermined by this, no less than by his theological rhetoric, as he strenuously promulgates the good news about Darwin. With his goal of converting the world to his evolutionary faith, this pontificating scientist is, in the end, hardly different from religious fundamentalists.

Before Coyne's dogmatism discredits those who undertake a sober study of evolution, we may hope that others who have a rigorous understanding of the theory will speak out and answer him. All would do well to heed James B. Stenson's counsel that "dogmatic fundamentalists do not reflect [religious] tradition, and dogmatic evolutionists do not fairly represent science." Coyne should spend his time reviewing the latest scientific literature, and perhaps get a more mature grasp on theology as well, before he returns to admonishing his scientific brethren to speak with one voice.


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