One of the ex cathedra assertions of Vincent Fleury, in a general public forum where his book and theory where discussed, early 20071, was:
Je suis désolé de devoir insister : ouvrez vos yeux, ça n’a AUCUN sens d’invoquer la fonction d’un organe, si l’ensemble des modifications possibles d’un animal ne sont pas quelconques. L’influence de l’environnement sur le développement de UN animal est égal à ZERO, et l’influence sur les mutations est égale à ZERO. ZERO fois ZERO= ZERO.
I’s sorry, I have to insist: open your eyes, there is no SENSE to invoque the function of an organ, if the set of possible modifications of an animal are not random2. The influence of the environment on the development of ONE animal is equal to ZERO, and the influence on the mutations is equal to ZERO. ZERO times ZERO = ZERO.
I was astonished by such an insistence with the ornamental capitalization for emphasis and my first reaction was to laugh at it.
It’s quite easy to explain to somebody how false this position is mentioning one or the other of the chemicals prohibited during pregnancy as examples, some of them being teratogenic, but Fleury don’t like chemicals in general. So I struggled to find examples where physical factors influence the development and act differentially in different alleles. I was at the time so much in the mechanical stuff, trying to understand Fleury’s model, that I completely forgotten thermosensible mutations, temperature being a fairly physical factor, influencing the development of individuals according to their genotype.
The idea stroke me much latter and I posted a few papers presenting such examples.
I was expecting that somehow Fleury would follow his advice to open the eyes, understand that his statement, is bloody false and step down. Misplaced optimism.
While it was still the period where he was trolling in the comments of my blog he didn’t commented on that point.
All I harvested was the remarks of a science blogger, friendly to Fleury but critic to his theory, that my examples didn’t showed major changes, they concerned details and some approximations are legitimate. Well I wouldn’t ever talk about lethal thermosensible mutations as a detail. And even slight modifications don’t fit with this vehement “ZERO times ZERO = ZERO“
In his equation describing the morphogenetic field he fails to take in account interactions with the environment which shape the spectrum of phenotypes a particular genotype may adopt, be it macroscopic, concerning the shape, or molecular, concerning the regulation of genes expression.
One could transpose this misunderstanding to his incredulity when he is facing integration of positional information at the cellular level during development. The only external influences he acknowledge are mechanical.
2. I’m translating “quelconque” as “random”, and don’t ask me what he means there.