"Stephen D. Williams" wrote:
> > > Three decades ago, Frank Salisbury of Utah State University described the
> > > odds this way: "Imagine one hundred million trillion planets, each with an
> > > ocean with lots of DNA fragments that reproduce one million times per
> > > second, with a mutation occurring each time. In four billion years, it
> > would
> > > still take trillions of universes to produce a single gene -- if they got
> > > lucky."
> Hogwash. Genes didn't spring fully formed. Or cells (there's a movie
> where the main protagonist decides to believe in God/creation because a
> 'cell' couldn't have sprung into existance), or even DNA/RNA.
And in other news, don't forget about how NASA had to adjust the trajectory of the
moonshots to account for the period of time when the Earth's revolutions were
stopped per Biblical "history"...
So *some* of the problems with Salisbury's analysis... The raw numbers might be
correct *iff* you make the following unreasonable assumptions. First, it's
assuming that these "fragments" are disconnected; it starts from billions of
totally random base pairs and proceeds flipping randomly, a single base pair
mutation at a time. Given this sort of linear, uncorrelated, totally random
process, sure, the time to arrive at a reasonable genome probably exceeds the age
of the universe, much less the age of the planet.
But it doesn't work that way. The process *had to be* nonlinear, self-organizing
/ self-reinforcing, and "interactive" with the environment itself.
Salisbury's analysis misses four important things. First, the length and
complexity of the genome (and its pre-biological organic molecule precursors) have
increased over time. Smaller and simpler molecules incrementally lengthen and
gain complexity over many iterations. Second, there was probably "guidance" in
the form of environmental influence on structure and function. There are two
schools of thought as to how those original nucleotide chains happened: either by
interaction with the surface chemistry and structure of clay beds, or by
interaction among organic molecules in the presence of surfactants, i.e. on the
surfaces of bubbles. Either way, certain structures in the environment may have
dramatically influenced how these molecules got laid out --- in some senses, you
can regard DNA as a "mask" for proteins, etc. that they came into contact with in
the environment. No surprise that cell membranes are a lot like various naturally
occurring organic bubbles...
Third miss is in the fact that some changes are self-reinforcing. DNA doesn't
ONLY interact with the environment, it also interacts with itself and with other
nucleic acids. Finally, all of these things --- plus natural selection --- add up
to a "hill climbing" process that is very much nonlinear, and much more effective
than endless iterations of random bit twiddling.
I think it's MUCH *more* wonderful, awesome, and magnificent to assume that such
things can happen naturally, as a consequence of the laws of physics and nothing
more, than to assume some omnipotent watchmaker manually turning the crank.
Just some lunchtime musings over a Sonic burger...
This archive was generated by hypermail 2b29 : Sun Apr 29 2001 - 20:26:06 PDT