Re: Is there any reason for the evolution to be one way

On Mar 24, 7:15 pm, Bob Kolker <nowh...@xxxxxxxxxxx> wrote:
Shaktyai wrote:

know of !!!).

Apparently evolution never crosses twice its steps. My explanation is
that when a mutation occurs in a gene the free energy is lowered and
the gene reachs a more stable state. External conditions just filters

Please produce the Lagrangian Density Function of a gene and shows that
it is going to its variational extreme.

As far as I can tell, genetic variation is random and selection is a
function of the ambient environment. We are the latest step in a random
walk across a dance floor. The dance we dance is determined by natural
selection.

Bob Kolker

Random walk with p=q=0.5 have a zero mean deviation: ie no evolution.
That goes for a model where a mutation of a gene is modeled in a 1D
space. One step on the right or one step for each mutation from state
A to B, from B to C, etc...
Such a model can not reproduce the experimental facts: evolution =
there is a non zero mean deviation = there is a drift in the random
walk. I have in mind the 1D model (and I may be wrong there !), so the
only solution is to assume that in general: p(A->B) is different from
p(B->A).
To justify this I was thinking about the thermodynamics of a mutation.
In my point of view, the two probability can be equal if E(A)=E(B).
If the free energy of the initial and final state are different then
the system will always spontaneously evolve toward the lower energy
state and the two probability should be different. Of course there is
always the possibity to bridge the energy gap with either a chemical
catalyst, a photoabsortion, or an electronic colisionnal excitation
(electron beam).
I might be all wrong but is there a systematic study of the energy
required for a mutation to spontaneously happen ?

There is a lot of talk about Hamiltonian of Darwin's systems. To write
down a satisfactory theory, one must have a density probability whose
integral is always one. In kinetics, this very fundamental point is
induced by the hamiltonian structure that induces Liouville's theorem.
In information theory, the probility space is constant and well
defined. But in biology it is far from obvious.


.

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