I have found your discussion of my recent articles with Bruno Maresca - "Sudden origins..." and "Do molecular clocks run at all?" - interesting. Since comments seem to derive primarily from press releases and secondary citations thereof, I shall try to clarify a few things. First, I am an evolutionary biologist who happens to teach in an anthropology dept. My courses are often cross-listed with Biology and Geology as well as History and Philosophy of Science. My first published volume was Models and Methodologies in Evolutionary Theory (1979), co-edited with H. Rollins (who did his PhD in geology with Eldredge and Gould). Maresca is a leader in the field of cell membrane physiology and stress proteins, who happens to teach in the school of pharmacy at the University of Salerno.
Cells' molecular (DNA etc) are not constantly changing in any significant way. Mutation rate (a combination of UV-induced change and transcription error) is extremely low, c. 10 (superscript -8 to -9) - and mutation can affect any cell, not just gamets. We point out that in order to provide the potential for change - e.g. by allowing different signalling pathways - there has to be a mechanism for increasing the effective mutation rate. We suggest that spikes in stress that exceed an organism's capacity to produce sufficient stress proteins to maintain DNA homeostasis represent a possible mechanism. However, as has been known since the early 1900s (see Bateson) and was fundamental to the statistical formulations of the mathematical population genetics (Haldane, Wright, Fisher), most "mutations" (however defined) emerge in the recessive or unexpressed state. As such they spread silently through a population until heterozygotic saturation is achieved, when homozygotes for the "mutation" will begin to emerge. Of course, different individuals will have different stress responses. But while the "environment" may provide the provocation for potential change (unless, as if most likely the case, the result is cell/organism death), the expressed novelty will have nothing to do with the "environment" in which its bearers find themselves. This is not the model of punctuated equilibria, as either first formulated by Eldredge or later co-opted by Gould, since the original model was strictly selectionist. Our model is not (or was it when I began formulating it in Sudden Origins). As for criticizing Darwinian emphases on constant and gradual change, while the quote from Darwin indicates that he recognized that there could be stasis, it is obvious from the total corpus of his writing that he believed this to be a minor case. If one reads the fundamental monographs underlying the evolutionary synthesis by Fisher, Morgan, and then Dobzhansky (2nd ed) and Mayr, gradualism is the major tempo, with accumulated small change the scenario. It is this version of neo-Darwinism informed the hardcore sociobiologists and their scions the evolutionary psychologists. The history of evolutionary biology gives the needed perspective here, as it also does to appreciating that the extrapolation from bacterial genetics/genomics of the 1960s to multicellular organisms, while seemingly valid at the time, is now known to be totally inappropriate, even though it continues to inform the use of molecular clocks. With regard to those of you who are interested in the increasingly influential field of evolutionary developmental biology (perhaps some of you may know it as "evo-devo"), I direct you to publications by Gerd Mller (director of the KLI), Stuart Newman, Massimo Pigluicci, Gnter Wagner et al, who are among the leaders in what is clearly an intellectual shift from Darwinism - which we know is not a viable model for the origin/emergence of novelty.
™ Version 4.2
