Quote:
Originally Posted by damian1727
''the odds for assembling a single gene are between 4/-160 and 4/-360
there has not been enough time since the formation of the earth to try a number of nucleotide base combinations even remotely comparable with these numbers.the numbers of bacteria on earth is about 10/27 assuming reproductive time of 1 hour there have been at most 10/40 bacteria in entire past history.....with the order of nucleotide bases per bacterium at 10/7 it has only been possible to try out 10/47 nucleotide combinations...which is 52 orders of magnitude to small(for what ? sorry)
|
Speaking purely as a layperson with no special training in either evolutionary biology or probability theory, I think such probabilistic calculations fail to take into account the constrained randomness that characterizes evolutionary processes, and the emergence of complexity from relatively simple initial conditions and rules.
The limited number of molecules sufficiently small, abundant, and chemically flexible enough to rapidly produce zillions (the technical term, I believe) of combinations in the primeval liquid water soup already imposes a broad but definite constraint on the range of possibilities.
Combinations that can replicate reliably into similar but not necessarily identical versions of themselves further constrain the range of possibilities, restricting the extent of random variability to perhaps mere millions rather than gazillions (approximately the square of a zillion) of options.
As life continues to develop, each organism reproduces within a constrained range of possible random mutation, and each mutation is further constrained by intrinsic and extrinsic factors that allow only a small fraction to survive and reproduce again.
Counting up the mathematically possible number of nucleotide combinations is not terribly relevant except to demonstrate the severe winnowing of that theoretical total by the constraints placed upon the randomness of evolutionary development by environmental conditions and past mutational history.
Life is not the product of pure unconstrained randomness, as the probabilistic statistics cited by damian1727 might suggest. Life is rather a dialectical process emerging from the dynamic interplay of determinism and randomness, two principles which on their own are sterile and static.
This illustrates a paradoxical aspect of the concept of infinity: life is infinitely variable, but within limits. Which I suppose is no more mysterious (and no less) than the infinity of fractional numbers found between zero and one.
None of which detracts from damian1727's excellent point about the value of such speculation in bringing home the miraculousness of life on Earth, regardless of its cosmic rarity or commonness, and the reciprocal obligation owed by giant-brained conscious beings to the biological matrix from which consciousness, and even better things like hoppy beer, jazz, and snuggling, emerged.