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Wednesday, March 14, 2007

Molecular clocks: Right twice a day?

Jeffrey H. Schwartz of the University of Pittsburgh's Departments of Anthropology and History and Philosophy of science and Bruno Maresca of the Department of Pharmaceutical sciences at the University of Salerno, Italy, have state that "there is no basis" for the view that a "molecular clock" (a presumed calculable rate of evolution) can determine the evolutionary history of a species. In an interesting and mostly quite readable paper published in Biological Theory (1(4) 2006, 357-371, and available online, Schwartz and Maresca show how fossil findings and molecular clocks have simply not matched.*

For example, in reviewing an attempt to make sense of human-ape differences, they write,
First among the inconsistencies is the admission that the accepted model of molecular change and its phylogenetic interpretation were assumptions, and then the declaration that, since these assumptions were widely accepted, one could embrace them as truths. But they are assumptions and testable.


They end up questioning whether the molecular clock theory is even tenable. It appears to have been held because it provides information, but as the information comes from untested assumptions, it is of unknown worth.

(*To see what this means, suppose you tried to construct a timeline for family events based on the assumption that your grandmother was born in 1924 - because her birth certificate say so. But when her age is given in other dated official documents, she seems to have been born in 1926. And everyone who could help you straighten out the problem is dead. Your choice of birth date will affect the timeline, especially when you are dealing with events for which your source recalls only, "That happens when your grandma was 47 ....")

This paper is must reading for people who think that we know much for certain about human evolution. As the Eurekalert press release notes,
..., it is not only the current molecular theory that intrigues Schwartz, but the failure of the scientific community to question an idea that is more than 40 years old: "The history of organ life is undemonstrable; we cannot prove a whole lot in evolutionary biology, and our findings will always be hypothesis. There is one true evolutionary history of life, and whether we will actually ever know it is not likely. Most importantly, we have to think about questioning underlying assumptions, whether we are dealing with molecules or anything else," says Schwartz.


(Note:Jeffrey H. Schwartz should not be confused with non-materialist psychiatrist Jeffrey A. Schwartz, lead author of The Mind and the Brain. )
Check out my book on the intelligent design controversy, By Design or by Chance?.

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