The logic of forms in the light of developmental biology and palaeontology.

11 pagesIf you ask palaeontologists, and indeed anyone interested in the theory of evolution, for the key words that encapsulate it, you will obtain the following results: adaptation, natural selection, speciation, but also ontogeny and phylogeny. The first three key words apply to the future of the individual and by extension to the future of the species: we are therefore dealing with adults of a reproductive age. The two other key words concern (i) the evolution of the morphology from the egg to the adult (individual ontogeny: short timescale) and especially what goes on in the black box called embryogenesis, and (ii) the modification of ontogenetic sequences over time, resulting in changes to adult morphologies (phylogeny: long timescale). After quite a long eclipse, coinciding with the advent of genetics at the beginning of the twentieth century and then the modern evolutionary synthesis in the 1940s, the ontogeny/phylogeny pair has recently enjoyed a steady revival of interest. Firstly under the impetus of S.J. Gould at the end of the 1970s [8], and then with the appearance, at the end of the 1980s, of what we now call developmental biology. This revolution in the biological sciences is comparable in importance to that which shook the earth sciences at the end of the 1960s with the emergence and rapid development of plate tectonics