Re: left versus right: did life begin in only one place?




<efffemm@xxxxxx> wrote in message news:e4idtq$15u0$1@xxxxxxxxxxxxxxxxxxxxxx
I read somewhere that living creatures could have long-chain molecules
with the helix either left or right handed, but all on this planet are
twisted the same way. And this suggested that life began from a single
starting point. If life began, say in ten different places, then the
probablity that all helices were the same is 1/512.
But what if for example, we got 3 left-handed and 7 right-handed?
All is fine until they spread around the world and mix.
The left-handed eat other organisms, but can't assimilate 70% of
their food, so their species starves to extinction sooner or later.
Whereas the dominant right-handers could eat the left-handers
without as much trouble.

Two points:

One is that there is no way today of distinguishing the hypothesis
that life arose once (and all modern organisms are descended from
that ancestor) from the hypothesis that life began several times
(but all modern organisms are descended from only one of those
ancestors). So, so far, your suggestion is reasonable.

But second, I strongly doubt that competition between early organisms
consisted of them eating each other. If everyone is eating everyone
else, everyone is destined for extinction. You can't run an ecosystem
that way any more than you can run a modern economy in which everyone
hires everyone else to clean their house. You need to have most
organisms engaged in 'primary production' - that is, eating nothing
but water, air, minerals, and sunlight. And it is the primary producers
that will determine which direction the helices twist.

The primary producers compete indirectly - for water, minerals, and sunlight.
They don't kill and eat each other. But the competition is relentless
nonetheless, and we would expect that, over time, the descendents of one
would drive the descendents of another into extinction (because they were
more efficient, for example.)


.



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