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Dubious science in an excellent good show - Synchronicity swirls and other foolishness

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November 14th, 2009

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11:27 pm - Dubious science in an excellent good show
I've very much enjoyed the first two part's of Nova's 3 part exploration of human evolution, Becoming Human. So far, they have not only kept up with all the recent data that I've heard of, but they have also mentioned several things that I hadn't known, such as the fact that australopithecines had more ape-like arms and shoulders and so almost certainly climbed a lot as well as walking, and that one very likely reason for these creatures experiencing a significant growth in brain size was adapting to exceedingly rapid periods of drastic climate change in East Africa, which seems to have gone from arid scrub to deep lakes or back again in a thousand years, followed by a stable period and then another rapid climate change. I was also interested to hear more about the discovery of hominids (whether you call them late australopithecines or early homo erectus is merely a matter of terminology) in Dmanisi in Georgia.

So, an excellent show, but with one annoying flaw. Genetics is a vital part of all modern paleontology, we can use it to tell how closely two modern species are related, and if we have ancient DNA we can look at how closely that extinct species was to modern species. We can even use to to form a relative timeline of whether two species diverged before or after one of them diverged from another species. However, what it cannot reliably be used for is absolute dating. I've seen a number of cases that when it's been compared to the fossil record, the molecular clock hypothesis is wrong, because the rate of genetic change varies not just from one species to another (often drastically), but within a single species over time. Researchers are naturally fascinated with what genetics can do - the current work on reading Neanderthal DNA is fascinating, but the rate of radioactive decay is a stable dating tool, the rate of changes in DNA is not. Once again, it's a case of the new shiny tool being used for well more than it's good for.
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Date:November 15th, 2009 10:56 am (UTC)

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