} >My sources are pretty authoritive (see paper cites), and
} >clearly say that Eukaryotic cells appeared about 1.8-2.0 bya
} >(billion years ago), when the atmosphere became oxygen
} >-dominated after all the ocean's iron was finally oxidized.
} I agree with your timeline about the appearance of oxygen in the atmosphere,
} but I see no reason why only Eukaryotes could have caused it.
Especially since eukaryotes are largely emborged prokaryotes --
chloroplasts are cyanobacteria in a cushy position. But Robin's point
might have been the other way around -- eukaryotes need oxygen, and if
they appear as soon as there's enough O2 in the atmosphere, well, there
goes another part of the filter. The data's overall reliability is
still shaky though, I think, authoritative papers or no. We argued
about stuff like this in geology classes a bit.
I forgot to mention my favorite solution to the Fermi Paradox when
talking with Robin, though. They _are_ out there. They're being very,
very quiet. So as not to disturb us? No. Because they've all evolved
into Sagan's passive non-expansionists? No.
Because they're scared silly (or rather, silent) of the berserkers.
Even a NASA commission, I've heard, suggested that perhaps being too
loud wasn't such a good idea. I can imagine every other society
reaching our stage, having the idea of Darwinism on hand, being on the
brink of passing into a world state anyway (assumption, but plausible if
needed), seeing the great silence and deciding that for the Safety of
the Race We Will be Very Unobtrusive. No Gain is Worth a Risk to the
Species. If they ever get bored with this stage they might have turned
into advanced versions of Imperial China, which didn't care to explore
the world anymore, thank you very much. That stage does require
exploration to be expensive; the first stage just requires a good police
state. So the universe is filled with pessimistic versions of Niven's
State, Chinas, and Vinge's World State from "The Peddler" (although I
suppose something like the Peace Authority could work.) Paranoia is
probably far more reliably universal than altruism.
Now, even if you take this seriously it probably can't explain more than
1 or 2 orders of magnitude. (Especially since I'd hope for us to be the
exception.) But I love the idea. The berserkers aren't everywhere.
The berkserkers don't even exist. The idea, though...
Merry part,
-xx- Damien R. Sullivan X-) <*> http://www.ugcs.caltech.edu/~phoenix
Humans humans pay your dues
As never before you get to choose;
Become like us or fight and lose,
Great Ones evermore.
Powers evermore.