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Thanks colorado tanker.University of Chicago paleontologist David Jablonski fielded a hostile question: Why bother classifying organisms according to their physical appearance, let alone analyze their evolutionary dynamics, when molecular techniques had already invalidated that approach? ...The question launched him on a rigorous study that has culminated in a new approach to reconciling the conflict between fossil and molecular data in evolutionary studies... Until now, attention has focused on the dramatically different evolutionary history of certain lineages as determined by fossils or by genetics... No matter how they looked at it, the lineages defined by their fossil forms "showed an imperfect but very good fit to the molecular data," Jablonski said. The fits were generally far better than random. The few exceptions included freshwater clams, "a complete disaster," he said... They looked at the fits again, but this time focused on geographic range and body size. The result: a "spectacularly robust" match between the fossil and molecular data... The work backs up a huge range of analyses among living and fossil animals, from trends in increasing body size in mammal lineages, to the dramatic ups and downs of diversity reported in the fossil record of evolutionary bursts and mass extinctions.The main problems with the genetic approach are psychological -- overreliance on modeling and computer simulations, overgeneralization (mutation rates, stabilities), and inability to see the limits of using surviving DNA to tell anything about either its geographic origin or its antiquity. Obviously, areas with high infant mortality and fairly low birth rates (such as much of Africa) and/or tribal affiliation will show a skew toward supposed antiquity, simply because areas with agricultural surpluses of great antiquity (typically the riverine societies) will greatly expand the number of descendants of any one mating pair.To all -- please ping me to other topics which are appropriate for the GGG list.The Neandertal Enigma"Allan Wilson had always been described to me in superlatives, such as 'one of the real geniuses in science,' or 'the most arrogant guy I know...' [H]e apologized for putting me off so long and bluntly explained that the reason he had done so was that he did not trust me... 'The anthropological perspective on evolution is no longer valid; it has been overthrown. And yet the science writers who insist on talking to me come drenched in an anthropological perspective, and there is really no point in talking to them... It is paralytic. It prevents you from asking certain questions, and it forces you to ask others. The whole discipline invites you not to investigate.' |
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