Lucien Cuénot: a new review of the evolutionary thought by a pioneer of modern genetics

Lucien Cuénot is regarded as one of the fathers of modern genetics.
Lucien Cuénot is regarded as one of the fathers of modern genetics.
Research
(16/05/2017)

In 1915, the French zoologist Lucien Cuénot introduced the term “preadaptation” -a concept explaining phenomena of the evolutionary process- which focuses a scientific and philosophical debate during the entire 20th century. Cuénotʼs idea, had been related to a teleological idea of evolution, but it seems that it did not involve a definite conception of the evolutionary process in living beings, according to a study published in the journal Biological Journal of Linnean Society, by Professor Adrià Casinos, from the Faculty of Biology of the University of Barcelona.

Lucien Cuénot is regarded as one of the fathers of modern genetics.
Lucien Cuénot is regarded as one of the fathers of modern genetics.
Research
16/05/2017

In 1915, the French zoologist Lucien Cuénot introduced the term “preadaptation” -a concept explaining phenomena of the evolutionary process- which focuses a scientific and philosophical debate during the entire 20th century. Cuénotʼs idea, had been related to a teleological idea of evolution, but it seems that it did not involve a definite conception of the evolutionary process in living beings, according to a study published in the journal Biological Journal of Linnean Society, by Professor Adrià Casinos, from the Faculty of Biology of the University of Barcelona.

 

The evolutionary finalism and natureʼs complexity


Lucien Cuénot (1866-1951), regarded as one of the fathers of modern genetics, was a renowned figure in the field of science in his time. After the rediscovery of Mendelʼs law in 1900 -work by the scientists Carl Correns, Hugo de Vries and Eric V. Tschermak- Cuénot carried out his first Mendelian studies in mammals until his laboratory in Nancy (France) was occupied during World War I. Author of an extensive work on evolution -in particular, on the problem of adaption- Cuénot created the concept of preadaptation, an idea with a high evolutionary value.

In contrast, in 1982, paleontologists Stephen J. Could Gould and Elisabeth Vrba studied this idea of preadaptation, apparently related to teleological finalism, until reformulating and introducing another concept -the term “exaptation”- into the evolutionary debate. According to the study by Casinos, Cuénotʼs there was no finalism in Cuénotʼs idea and it did not respond to a teleological vision of the evolutionary mechanisms.

Preadaptation: a new evolutionary meaning

According to Adrià Casinos, who analyzes the scientific thought of the French geneticist in the framework of evolutionary studies, “Cuénot is an extraordinarily rich figure, who is now being rediscovered in some way. He was always against finalism but other authors used his ideas differently, they were in favor of finalism. R. A. Fisher and C. S. Stock were the first ones to bring up the accusation of teleologism. And if that was not teleology, the concept of preadaptation was not necessary for these authors because it meant it was the same as adaptation”.

However, these two concepts would not be equivalent in the framework of evolution, since “preadaptation involves a change of function without any structural change, while adaptation involves a structural transformation as a response to a certain selective agent. Since I refuse the possibility of a character being ex nihilo, that is, not derived from another, structural transformation is not necessary” says Casinos, professor from the Department of Evolutionary Biology, Ecology and Environmental Sciences, and expert on biomechanics, functional morphology and history and philosophy of biology.

For Casinos, the revision by Gould and Vrba ignores Cuénotʼs pioneering task in the evolutionary speech. “These authors prefer the term “preaptation” to “preadaptation” so that the concept of “exaptation” would equal the old preadaptation, while “preaptation” would be the corresponding situation to the first function. That is, the feather was a “preaptation” for dinosaurs, with a function of thermal insulation, but it is an “exaptation” in birds because it gained a new function, related to flying. In my opinion, this nuance was unnecessary”.

Nonetheless, not all are ideological differences and it would be possible to find some points in common within the conceptual debate. “The coincidence between Cuénot and Gould and Vrba would lie in accepting that a structure can start developing a new function without important changes” said Casinos.

“In addition, the terms “preadaptation” and “exaptation” coexist in the current scientific literature. There is bibliography that shows how the use of the term “preadaption” is still active. Its equivalence, in particular, could be synthetized comparing it to the fact that preadaptation (Cuénotʼs concept) is the sum of the concepts of preaptation and exaptation”, concluded Casinos.