On 14/08/2012 6:12 PM, dlzc wrote:
Dear Yousuf Khan:

On Tuesday, August 14, 2012 1:47:20 PM UTC-7, Yousuf Khan wrote:
On 11/08/2012 12:06 PM, dlzc wrote:
On Friday, August 10, 2012 6:56:22 PM UTC-7, Yousuf Khan wrote:

...

The first 3 billion years was wasted in
single-cell form. Complex life only started
about 600 million years ago, probably after
the last Snowball Earth. If other planets
undergo quicker transitions from single-cell
to complex life, then they could save upto
3 billion years.

That is probably when the first DNA "virus"
infected an RNA host cell. Corresponds
reasonably well with the formation of free
oxygen (at 500 million years).

The fact that complex life arose almost
simultaneously with the end of the Snowball
Earth period, I would say that the
environment had more to do with the evolution
of complex life than viruses changing DNA code.

What if you produced a virus, or collection of viruses, to do your terraforming for you? If RNA organisms are the target...

Well, now we're getting into science fiction. So what intelligence were
terraforming us? And who terraformed them? Actually sounds a bit like
the god debate: who created god?

Viruses must've been changing lots of DNA
code prior to that, but Snowball Earth happened
only once (so far as we know).

We have tidal rhythmites dating back to 2.2 Gy, not that that helps, but there were a few periods of glaciation indicated there, when lunar recession was nearly stagnant (no tides = "Snowball Earth").

How do these indicate periods of glaciation?

If such is drifting on the stellar wind,
being in a void as we are, could slow how
long it took to get here. Cooler stars
might be easier to let this stuff in...

What exactly are you referring to when you
say, "let this stuff in"? Are you talking
about cosmic rays, interstellar dust, etc.?

Panspermia. Something like "The Chase",
http://en.wikipedia.org/wiki/The_Cha..._Generation%29
... only instead of implanting on a planet, simply pumped into intrastellar flows, like dandelion seeds.

That's assuming that panspermia is just allowed to drift in randomly. If
we were terraformed, then it was probably aimed at us pretty precisely,
rifle-style, rather than shotgun-style. If rifled at us, I doubt a puny
little solar wind is going to stop the stuff from coming in.

Yousuf Khan