Dollo’s law, the symmetry of time, and the 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 titled “An epistatic ratchet constrains the direction of glucocorticoid receptor evolution”. 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. This is the last of three posts discussing it. (see here and here) 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 20th century paleobiologist, was interested in discerning phylogenies. He maintained that one could always Read More ›

Nature Paper Reaches “Edge of Evolution” and Finds Darwinian Processes Lacking

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 titled, “An epistatic ratchet constrains the direction of glucocorticoid receptor evolution.” 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. 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 Read More ›

Nature Publishes Paper on the Edge of Evolution

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 titled “An epistatic ratchet constrains the direction of glucocorticoid receptor evolution.” 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 Read More ›

Bloggingheads Explains

In a new segment, Bloggingheads chief Robert Wright and Bloggingheads correspondent George Johnson go on for 75 minutes about the trauma of a pair of heretics (me and Paul Nelson, on separate segments) appearing on their site. I would urge everyone who doesn’t have pressing matters to attend to, such as the need to wash your hair, to tune in for the full time. It’s really fascinating in its way to see two grown men in such a hand-wringing lather. It’s also fascinating to see that neither of them in 75 minutes offers a reason for the correctness of their own views, or the wrongness of ours. The closest they come is when George Johnson invokes the hoary “methodological naturalism.”

Reducible Versus Irreducible Systems and Darwinian Versus Non-Darwinian Processes

Recently a paper appeared online in the journal Proceedings of the National Academy of Sciences, entitled “The reducible complexity of a mitochondrial molecular machine.” As you might expect, I was very interested in reading what the authors had to say. Unfortunately, as is all too common on this topic, the claims made in the paper far surpassed the data, and distinctions between such basic ideas as “reducible” versus “irreducible” and “Darwinian” versus “non-Darwinian” were pretty much ignored. Since PNAS publishes letters to the editor on its website, I wrote in. Alas, it seems that polite comments by a person whose work is the clear target of the paper are not as welcome as one might suppose from reading the journal’s Read More ›