Begin forwarded message:

From: Richard Gillilan <r...@cornell.edu>
Date: June 23, 2009 9:43:20 AM EDT
To: "Nadir T. Mrabet" <nadir.mra...@medecine.uhp-nancy.fr>
Subject: Re: [ccp4bb] structure <-> function

A very interesting question.

Stephan Jay Gould was well known for his argument that evolution is contingent on all kinds of factors (like meteor impacts etc.). He argued that if we replayed geologic history with minor tweaks, life might be totally different or not exist at all. Based on these ideas, I think a lot of people will say evolution has "no direction." It meanders aimlessly. This is in contrast to idea that life is somehow always improving or becoming more complex or more advanced (some kind of "progress").

But I think anyone who's used evolutionary programming to solve numerical problems realizes that it can be an optimization process under some conditions that finds "best" solutions. I think there are certainly situations in which external contingencies are limited and so evolution can be viewed as a process that sorts out "best" solutions to certain physical problems.

If a certain reaction needs to be catalyzed in order for a species to live and reproduce, there may well be only one, or a few good ways to do this ... limitations of fundamental physics. The fold and sequence of the proteins may be different, but they still have to reduce the activation barrier for the reaction, and that involves binding a certain fixed intermediate geometry of a species that has donors and acceptors in fixed locations.

Similarly, there are a fixed number of ways objects can achieve locomotion. Creatures evolved to move efficiently in their element to compete for resources have to solve the same basic physical problems. When those problems are simple and have only a few solutions, you have convergence.

ps, if you haven't seen some of Karl Sims' evolved virtual creatures videos, they are really worth watching. Astounding in fact: www.karlsims.com/evolved-virtual-creatures.html

Richard Gillilan
MacCHESS

On Jun 22, 2009, at 11:16 AM, Nadir T. Mrabet wrote:

Ok, now we can perhaps debate of another problem.
With a multiple choice question that has more than one acceptably good answer,
is it "convergent", or rather "independent", evolution?

This multiple choice question is open for discussion.

Greetings,

Nadir

Pr. Nadir T. Mrabet
   Cellular & Molecular Biochemistry
   INSERM U-954
   Nancy University, School of Medicine
   9, Avenue de la Foret de Haye, BP 184
   54505 Vandoeuvre-les-Nancy Cedex
   France
   Phone: +33 (0)3.83.68.32.73
   Fax:   +33 (0)3.83.68.32.79
   E-mail: nadir.mra...@medecine.uhp-nancy.fr


Reply via email to