Edge of Evolution

Nature has recently published an interesting paper which places severe limits on Darwinian evolution. The manuscript, from the laboratory of Joseph Thornton at the University of Oregon, is entitled “An epistatic ratchet constrains the direction of glucocorticoid receptor evolution”. ( http://tinyurl.com/yeq2cy8 ) The work is interpreted by its authors within a standard Darwinian framework, but the results line up very well with arguments I made in The Edge of Evolution. ( http://tinyurl.com/yba6vba ) This is the last of three posts discussing it. Bridgham et al (2009) are interested in the reversibility of evolution, and discuss their results in terms of something called “Dollo’s law.” Louis Dollo, an early 20thcentury paleobiologist, was interested in discerning phylogenies. He maintained that one could always distinguish ancestral forms from descendant Read More ›

Nature has recently published an interesting paper which places severe limits on Darwinian evolution. The manuscript, from the laboratory of Joseph Thornton at the University of Oregon, is entitled “An epistatic ratchet constrains the direction of glucocorticoid receptor evolution”. ( http://tinyurl.com/yeq2cy8 ) The work is interpreted by its authors within a standard Darwinian framework, but the results line up very well with arguments I made in The Edge of Evolution. ( http://tinyurl.com/yba6vba )This is the second of several posts discussing it. Using clever synthetic and analytical techniques, Bridgham et al (2009) show that the more recent hormone receptor protein that they synthesized, a GR-like protein, can’t easily revert to the ancestral structure and activity of an MR-like protein because its structure has been adjusted by selection Read More ›

Nature has published an interesting paper recently which places severe limits on Darwinian evolution. This is the first of several posts discussing it. The manuscript, from the laboratory of Joseph Thornton at the University of Oregon, is entitled “An epistatic ratchet constrains the direction of glucocorticoid receptor evolution”. ( http://tinyurl.com/yeq2cy8 ) The work is interpreted by its authors within a standard Darwinian framework. Nonetheless, like the important work over the years of Michigan State’s Richard Lenski on laboratory evolution of E. coli, which has shown trillions of bacteria evolving under selection for tens of thousands of generations yielding just broken genes and minor changes, the new work demonstrates the looming brick wall which confronts unguided evolution in at least one system. And it points Read More ›

Dear Readers, Here I respond to the unfavorable review of The Edge of Evolution by Kenneth R. Miller inNature. Like Sean Carroll, whose review in Science I discussed earlier, he employs much bluster. But Miller goes well beyond simple bluster. I overlooked Carroll’s rhetoric and dealt only with his substantial arguments. This time I’ll do things differently. Today I’ll respond to Miller’s substantive points. Tomorrow we’ll take a closer look at his style of argumentation. After mentioning that de novo resistance to chloroquine is found roughly once in every 1020 malaria parasites, and quoting several sentences from The Edge of Evolution where I note “On average, for humans to achieve a mutation like this by chance, we would need to wait a hundred million times ten Read More ›