Re: [asa] Finding Your Inner Fish

From: Randy Isaac <>
Date: Sat Apr 18 2009 - 10:21:31 EDT

Thanks, Mike. Very interesting. Are you saying that ideas of homology in the embryonic stage waxed and waned in the last 150 years? Didn't Darwin put some emphasis on it while Haeckel over emphasized it. Then are you suggesting it was discounted and is now becoming more plausible at the protein level?

  ----- Original Message -----
  From: Nucacids
  To: Randy Isaac ;
  Sent: Friday, April 17, 2009 10:07 PM
  Subject: Re: [asa] Finding Your Inner Fish

  Hi Randy,


  "The title of his book reflects his perspective that humans contain the essence of 3.5 billion years worth of life. Our genetic structure reflects elements of all the other organic structures. He noted that in the past 15-17 years, many of the Nobel prizes in medicine and related biological fields have been for studies on worms and parasites and other small species. He inferred that many of the critical processes in our own bodies were reflected in the "lower" life forms and could be more easily studied there. He also spoke of the comparison of human and shark embryos and he showed the early similarities of analogous structures in these embryos. As a fish paleontologist, he has been teaching a first-year anatomy course to the U of Chicago medical school. He tells them that all the major human structures were all first seen in fish."


  Yes, this is all very cool. But it's better than this. If anyone would like to see single-celled amoeba form a multicellular life form before your very eyes, check out this:


  The amoeba coalesce into a multicellular life as a response to stress. What's makes this so super cool is that they use the same circuitry the human body uses to respond to extreme stress: G protein receptor, G proteins, adenylyl cyclase, cAMP, and protein kinases. Humans use this circuit as part of their "fight and flight" response, where it is triggered by the hormone epinephrine (adrenalin). I don't know if these amoeba make or use epinephrine, but others do:


  Someday I may write a book entitled, "Our Inner Amoeba" as these continual findings of deep homology enhance the plausibility of my particular front-loading hypothesis.


  BTW, I should also mention that such deep homology was not predicted to exist by the Modern Synthesis. On the contrary, it was predicted to not exist. Again, from Koonin's paper, "Darwinian evolution in the light of genomics":


  "Moreover, the adaptationist paradigm of evolutionary biology seemed to imply that genes, whatever their molecular nature, would not be well conserved between distant organisms, given the major phenotypic differences between them, as emphasized in particular by Mayr, one of the chief architects of the Modern Synthesis (21)."


  Or, as Mike Levine explained:


  "And so to see that genes that are doing such profound things in the fruit fly - making head from tail, stomach from back, thorax from abdomen - are conserved, related in other animals . this was just not predicted by anybody. At least nobody that I ever read. So this was very profound. It meant that there could be a common blueprint for all animal life on this planet.


  In the case of the discovery of common homeotic genes among all animals, there was a strong sense in the '70s and the '80s that embryonic development among different animals involved completely different molecules, completely unrelated. This was such a strongly held view. And so, yes, it came as a huge surprise not only to people like my mother who says, "My God, an earthworm and a mouse? An earthworm and me, sharing things in common?" But it came as a surprise to other scientists that there was this profound conservation of mechanism of building embryos among all these different kinds of animals."


  - Mike

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Received on Sat Apr 18 10:22:06 2009

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