[extropy-chat] ET is a Bacterium was Dark Matter and ET.

[The Avantguardian]

--- BillK <pharos at gmail.com> wrote:

> Why switch to talking about bacteria and kudzu? I
> doubt if they have
> the capability to colonise the galaxy. 

Well the kudzu are screwed. But bacteria on the other
hand may be the only form of life that HAS colonized
the galaxy so far. There are many biologists (Francis
Crick and myself for example) that believe that life
did not originate on Earth, instead it originated
elsewhere and colonized the then recently cooled
Earth. This theory is called pan-spermia. Aside from
the fact that there is no real evidence, fossil or
otherwise, of an "RNA world" on ancient earth, there
are reasons that it is a valid origin theory. It seems
very likely that all life on earth came from a single
progenitor ancestor. If life just kind of happened
here, then I think you would expect to see different
clades of life starting concurrently but instead it
radiated out from a single form. Other lines of
evidence include, nearly uniform genetic code, same
fundamental metabolic pathways, same 20 amino acids,
and same chirality.
     That bacteria could survive long enough in space
to colonize other worlds is pretty well documented.
Any of the rod shaped bacilli of the type that contain
Anthrax as a representative species can form
super-resistant endospores. These spores can survive
in a near inanimate state without food or water for
indeterminately long periods of time in very harsh
conditions including hard vacuum, ionizing radiation,
and extremes of heat and cold. It seems that such
spores could be easily disseminated by asteroid and
comet strikes or possibly even by supernovae. They
could hitch a ride on planetary debris thrown out as
ejecta from such cataclysms to captured by the gravity
of a passing star.
     These endospores could potentially survive for
thousands of years in the interstellar void and all
they need to "wake up" is exposure to water and
nutrients.

http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=99004

Excerpts from article:

Reliable reports exist of the recovery and revival of
spores from environmental samples as old as 105 years
(54, 81, 154), and there recently appeared a somewhat
more controversial report that viable Bacillus
sphaericus spores were recovered from the gut of a bee
fossilized in Dominican amber for an estimated 25 to
40 million years (20)!

With the LDEF mission, for the first time B. subtilis
spores were exposed to the full environment of space
for an extended period of time (nearly 6 years), and
their survival was determined after retrieval. The
samples were separated from space by a perforated
aluminum dome only, which allowed access of space
vacuum, solar UV radiation, and most of the components
of cosmic radiation (72). Figure 12 shows that even in
the unprotected samples, thousands of spores survived
the space journey (from an initial sample size of 108
spores). All spores were exposed in multilayers and
predried in the presence of glucose. The spore samples
had turned from white to yellow during the mission, a
phenomenon which is probably due to photochemical
processes. It was suggested that all spores in the
upper layers were completely inactivated by the high
flux of solar UV radiation. With time, they formed a
protective crust which considerably attenuated the
solar UV radiation for the spores located beneath
them. Therefore, the survivors probably originated
from the innermost part of the sample

The Avantguardian 
is 
Stuart LaForge
alt email: stuart"AT"ucla.edu

"The surest sign of intelligent life in the universe is that they haven't attempted to contact us." 
-Bill Watterson

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