Tuesday, March 3, 2009

March 09 update

Trying to stick to the theme with these. First a couple of articles on Luca, the Last Universal Common Ancestor. I think this a great concept, after all evol theory predicts such an ancestor so why not try to characterise it via modern genetics?

The Annilas are attempting to explain the origin of life within the context of thermodynamics. Living organisms are extremely complex examples of the tendency for chemical reactions to occur which redistribute energy to achieve maximum entropy. I think this is right although I am inclined to think that the laws governing the flow of information start playing a part very early on, and influence the outcome. What are these laws? Well natural selection and related principles obviously. Genetic drift.  I'm sure there are others though I have difficulty pinning them down. You need a finite set of symbols that can be combined in infinite ways.  Agents that can exchange these symbols within a framework of common intelligibility. Can this really all develop from chemical reactions that redistribute energy? Well yes, but the network needs to be there from the start. This is why I've thought perhaps a spongelike substrate being the habitat of LUCA. And that LUCA may have been a sort of super organism, like the fungi today that cover vast areas. Anyway, next item:

Turns out RNA can combine to form long chains under certain conditions. 
Evidence found of multicellular organisms that predate the Ediacaran fauna?
Well perhaps more like around the same time, but dating the ediacarans has been problematical.
Horizontal transfer of genes between mammal species. DNA just keeps finding new ways of getting around.

And finally a completely irrelevant one, the roar from outer space."The universe really threw us a curve," Kogut said. "Instead of the faint signal we hoped to find, here was this booming noise six times louder than anyone had predicted."

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