The whole question of the jump from non-life to the simplest known
bacteria has left me wondering about what would constitute life
_simpler_ than that of a bacteria, or more basically, what would the
"primordial soup" out of which bacteria or first life would have
spawned.
A bacteria has a membrane that separates itself from its environment.
It is also capable of replicating itself.
A compost pile, in contrast has no clear boundary separating its
environment, but it can grow over time. Could it be useful
conceptionally to "dumb down" the definition of life or protolife to
basically a self-perpetuating process?
Granted, _today_ a compost pile (or soil) contains all kinds of
bacteria within it, but perhaps the "primordial soup" have been
basically a bacteria-less "compost pile" that even without bacteria
grew in size and complexity over time.
Even simpler examples of self-perpetuating phenomena include fires and
storms.
A fire will continue to grow until it consumes its available fuel,
acting in a very similar manner to a bacteria colony in a petri dish
that will continue to grow until it runs out of its biochemical food.
Further, a fire provided with a steady source of fuel will continue
indefinetely.
A thunderstorm or hurricane is even simpler. It does not need any
organic matter at all but simply water and temperature differentials.
Once "born" it continues and feeds itself (again based on temperature
differentials) until it "dies", having again runout of fuel (and
dissipating) or having been torn apart by competing atmospheric
conditions. On Jupiter, the hurricane-like "great red spot" has
continued to exist for 300 years.
Lightning from primordial thunderstorms occuring across a methane-rich
early Earth atmosphere has been proposed as the means to initiate the
chemical reactions that eventually produced more complex organic
compounds. The growth _of the amount and complexity_ of these organic
compounds in the Earth's primordial seas itself could be imagined as
"protolife" (as basicaly a gigantic "compost pile" or again that soup)
and within this soup some self-perpetuating reactions could have begun
occuring.
Obviously, the above scenario is nothing new. What could be fruitful
is if a non-DNA based self-replicating system could be pulled out of
such a soup similulated in the lab.
Dennis
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