dvunkannon
Posts: 1377
Joined: June 2008
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| Quote (OgreMkV @ Mar. 01 2011,00:21) | David, one point about the vent stuff.
(Again, this is my limited study of the subject, so take with salt and read more than just me)
The photosynthetic compounds have analogues in chemosynthetic organisms. Some of them seem to be more primitive versions in the CS organisms. If that is correct, then the equipment needed to take advantage of the sun, developed first in the CS organisms, then was coopted for photosynthesis.
Did I say this already?
Man, isn't cough syrup with codeine awesome? |
Never argue with a man drinking cough syrup.
That said, I don't think your point on chemo-synthesis preceding photosynthesis is dispositive for vent vs. surface OOL. No one is arguing that surface OOL relied on anything like the photosynthetic pathways to get energy into the system. It relied on photons directly exciting molecules, on phosphate compounds floating by in abundance.
Look at the first graph in that paper Alan linked to. The Archaean Expansion enriched the use of iron, iron-sulfur, etc, while the genes for exploiting phosphate compounds significantly predated the AE. To me that says solar powered phosphate chemistry was earlier than vent exploiting metallo-chemistry.
Not that there needs to be a great dichotomy in our thinking. As I've said previously, the guys behind the Zinc World hypothesis point out that processes which we now associate with deep sea vents were occuring at the surface 3.5 billion years ago. Volcanoes spewing megatons of zinc sulfide and iron sulfide, forming the deposits we are still mining today. These surface deposits getting hit by UV, storing energy that can later be transferred to other molecules.
There were plenty of undersea vents back then, life was incipient in every place simultaneously. Where it first blossomed may be very hard to untangle.
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I’m referring to evolution, not changes in allele frequencies. - Cornelius Hunter
I’m not an evolutionist, I’m a change in allele frequentist! - Nakashima
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