press releas writes:
Jeffrey H. Schwartz, University of Pittsburgh professor of anthropology in the School of Arts and Sciences, is working to debunk a major tenet of Darwinian evolution. Schwartz believes that evolutionary changes occur suddenly as opposed to the Darwinian model of evolution, which is characterized by gradual and constant change.
I don't understand why such a big deal is made out of this notion of constant gradual change. Does anybody even believe it any more? Did anybody ever insist that the rate of evolution should be constant? Surely it is plain from a cursory examination of the fossil record that the rate of morphological change is not constant. Some species change a lot in a short amount of time, others change a little over a long time. This is exactly what is predicted by population genetics, where population size, generation time, selection strength etc. will all cause the rate of evolution (measured in terms of morphological or genetic divergence) to vary.
It is perfectly normal practice when fitting a model of evolution to genetic data to incorporate variables representing variation in evolutionary rate across branches and even across codons within a gene. The punctuationist model can be and is fitted to the data in a large number of studies of comparative morphology - specifically, the model is simply a phylogenetic tree with branches of equal length. It's not that brain-taxing to see if such a model fits the data better than alternatives.
The idea that "gradual and constant change" is a "major tenet" of the modern synthesis is simply not true. But it is a press release after all. It would hardly say that Professor X is proudly conducting normal science in support of an established paradigm, now is it?
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