Todd,
there is a good refutal of the mathematics in Crawford and Marsh'
Nutrition
and Evolution. Their theory of substrate driven evolution is
fascinating.
They make life seem inevitable. It is a must read at your level. The
chemical substrates , once determined, become the highway down which
evolution must progress. As for U-turns- they are very difficult- as
you
say, it is easy to lose a gene, but to reproduce it is awesomely
difficult.

For a 30 amino acid protein (takes a 90 DNA sequence) to be randomly
produced - with 4 different DNA codes, this makes 4 to the power of
90= 10
to the 54 = a billion billion billion billion billion billion. Makes
the
odds of being hit by an asteroid look good. Even with 6 billion
people, it
would take far longer than the age of the universe to produce the
protein
randomly. Thus you need another process and they describe it-
otherwise the
extraterrestials would have had to implant every single species every
single time a new species occurred. They make the process look lie a
giant
card game where the major gene componenets are shuffled in large
blocks, it
sounds good.

Further, classical chemical thermodynamics (J W Gibbs) whilst
powerful,
leaves many biological questions unanswered- thus our understanding is
too
incomplete to assert that life had to be implanted, we should merely
assert
that we cannot explain it scientifically.

Ben Balzer

Todd Moody wrote
>This is the reasoning that led Fred Hoyle, and John von Neumann, and others
> (Lee Spetner's book Not By Chance is a good source) to reject the random o
>rigin of life thesis as mathematically too remote to be believable.  Ir
>onically, even Francis Crick accepts this conclusion, for exactly the same
reasons.  This is what drives him to the "directed panspermia" theory
o
f life's origin, according to which life had to have been implanted
here by
 extraterrestrials.