Molecular Machines

An intriguing ‘hypothesis’ paper entitled “How a neutral evolutionary ratchet can build cellular complexity” (1), where the authors speculate about a possible solution to a possible problem, recently appeared in the journal IUBMB Life. It is an expanded version of a short essay called “Irremediable Complexity?” (2) published last year in Science. The authors of the manuscripts include the prominent evolutionary biologist W. Ford Doolittle. The gist of the paper is this. The authors think that over evolutionary time, neutral processes would tend to “complexify” the cell. They call that theoretical process “constructive neutral evolution” (CNE). In an amusing analogy they liken cells in this respect to human institutions: Organisms, like human institutions, will become ever more ”bureaucratic,” in the sense Read More ›

Dear Readers, An interesting paper has just appeared in the Proceedings of the National Academy of Sciences, “Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli.” (1) It is the “inaugural article” of Richard Lenski, who was recently elected to the National Academy. Lenski, of course, is well known for conducting the longest, most detailed “lab evolution” experiment in history, growing the bacterium E. coli continuously for about twenty years in his Michigan State lab. For the fast-growing bug, that’s over 40,000 generations! I discuss Lenski’s fascinating work in Chapter 7 of The Edge of Evolution, pointing out that all of the beneficial mutations identified from the studies so far seem to have been degradative ones, where functioning genes are knocked out or Read More ›

This is the fifth of five posts in which I reply to Dr. Ian Musgrave’s “Open Letter to Dr. Michael Behe” on the Panda’s Thumb blog. Finally, Dr. Musgrave objects to my placing viral protein – cellular protein interactions in a separate category from cellular protein-cellular protein interactions. In Chapter 8 of The Edge of Evolution I had written: Another, more important point to note is that I’m considering just cellular proteins binding to other cellular proteins, not to foreign proteins. Foreign proteins injected into a cell by an invading virus or bacterium make up a different category. The foreign proteins of pathogens almost always are intended to cripple a cell in any way possible. Since there are so many more ways Read More ›