Henri Lecoq (1802-1871)
Henri Lecoq, who trained and practiced as a pharmacist was, in 1827, appointed the chair of natural history for the French municipality of Clermont-Ferrand. Throughout his life, he maintained strong interests in botany, geology and mineralogy. His studies of the paleontological record and plant biogeographical patterns, as well as insights from domestication history, led him to advance species transmutation as the most logical explanation for the distribution of biodiversity both in space and in time.
In the Historical Sketch of On the Origin of Species, Darwin remarked briefly on Henri Lecoq’s 1854 eight volume biogeographical work, Études de la Geographie Botanique de l’Europe. Noting the homage paid to Geoffroy Saint-Hilaire and Goethe in Lecoq’s work, and thus implying the author’s likely affinity for theories of transmutation and metamorphosis, Darwin (who complained that this work had “a great dearth of precise facts”) ended his acknowledgement with: “some other passages scattered throughout M. Lecoq’s large work, make it a little doubtful how far he extends his views on the modification of species”.
Darwin’s apparent indifference (and perhaps too casual a reading of Lecoq) notwithstanding, chapter 11 of volume I (“General considerations on species”) of Lecoq’s treatise on plant biogeography is a full-on defense of descent with modification. Lecoq presents three possible explanations of past and current biodiversity: successive (miraculous) creations, descent with modification (“filiation”), and “translation,” in which some members of already created species are preserved from extinction in the face of environmental catastrophe and are later transported to different parts of the globe to repopulate. Lecoq proceeds to argue for descent with modification as the best possible hypothesis for past and present distributions of species in the fossil record and around the globe.
Arguing that the forces acting in the course of deep geologic time provide “the key to the many phenomena and long transmutations that the brevity of our existence hardly allows us to suspect,” Lecoq suggested that species transmutation constituted a more plausible explanation for the trend in increasing species richness and diversity over time than did the theory of successive special creations in each new geologic era. Drawing on Lamarck and Saint-Hilaire, he wrote that the newer organisms were modified forms of ancestral organisms; and that the changes were wrought, not by mass destruction and new creations, but by evolutionary modification in response to changing environmental conditions.
Invoking a somewhat phylogenetic perspective, Lecoq stated that the “divergent or rather convergent and subordinate classifications, which are the only natural ones, already indicate a tendency for the successive disarticulation of the branches of a common stock, whereas it should not be so if the creations had been simultaneous.” Lecoq’s most compelling argument, however, is based on his and other’s biogeographical work. He wrote that the view of species as being evolutionary derived from one another received “new force from the geographical distribution of animate beings.” Noting that species belonging to the same genera tend to be confined to a particular region, Lecoq reasoned:
“If the creations had been all individual, and if each species had come out as it is now in the hands of the creator, there would be no reason why similar types should not be scattered in all the localities where they might find their conditions of existence. Instead, we see the same dominant forms in this or that region, and the organizational analogies lead us so far, that very distinct and separate localities retain some very particular types.”
Lecoq, like so many of his evolutionist contemporaries did not propose a mechanism by which speciation could occur, invoking instead the nebulous action of “external agents” and “geological and climatic changes.” Nevertheless, his Études de la Geographie Botanique de l’Europe contains a clear caution to readers not to underestimate the effects of deep geological time in producing change in the natural world. Pointing to artificial selection and domestication history, as Darwin himself would do in Origin, Lecoq wrote “When we see the possible alterations in present-day forms, when we reflect upon the profound modifications we have made in the two kingdoms of our domestic races, we cannot really assign any limits to the power of geological causes, to the action of the climate, to the external acting forces, and especially to the different convulsions to which we attribute the mineral waters, the emanations of gas, the volcanoes, the earthquakes, and the upheavals of the mountain ranges.”
All in all, it is not particularly “doubtful how far [Lecoq] extends his views on the modification of species.” He seems to have clearly been an evolutionist.