tomhendricks474{at}cs.com (TomHendricks474) wrote in
news:bqfu5r$jd2$1{at}darwin.ediacara.org: 

> << (and I like your definition of life 
> as that which can "feed and breed"). >>
> 
> 
> But that just isn't enough thinking here. To say life is that which
> 'feeds and breeds' misses the point.
> 
> For anything to feed abreed it first must react to some force that is
> forcing the change. If there were no force the
> Z*n nothing would change from the past conditions. And under
> conditions that never change then there are no variants and no
> selection. 
> 
> So let's ask the question that follows. What forces any chemicals to
> shift to feeding and breeding to survive and prosper in their
> environment? 
 

But that is a different question. And I disagree with your 
characterization of something "forcing" chemicals to create life. What 
happens instead is that those chemical combinations that do "feed and 
breed" increase in number, while those that don't but are otherwise 
stable (e.g. gold) in fact do not change. If your question is what 
conditions are necessary in order for life to arise, the answer is that 
there must be an energy gradient,  and an energy source which can impart 
sufficient energy to the molecules present to overcome the activation 
energies required to create more complex molecular assemblages. Note that 
the activation energy can be lowered by catalysts, which is why Tim Tyler 
among others believes that clays may be significant in the origin of 
life. Also note that simple thermal cycling, while it provides an energy 
gradient, may not be able to overcome activation energies, which is why 
lightning, UV, or high temperature thermal vents are generally thought 
necessary to start life.


Yours,

Bill Morse
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