HETEROCHRONY
| Collection | International Encyclopedia of Systems and Cybernetics |
|---|---|
| Year | 2004 |
| Vol. (num.) | 2(1) |
| ID | ◀ 1519 ▶ |
| Object type | General information, Methodology or model |
A differential rate of growth and/or developement in a living organism .
Heterochrony can be understood in two different meanings :
1) The differential growth rate of different organs in a living being. For example, in the human species, the head grows more than the rest of the body at the embryonic and fetal stages, but this trend is reversed after the birth.
2) The different rate of embryonic development in different species. The German biologist Ernest HAECKEL (1834-1919), comparing embryos of different species during their development, came to the conclusion that, at least in vertebrates, different growth rates produced very different animals from quite similar embryos. His idea that “ontogeny recapitulates philogeny ” proved later on to be a too simple evolutive principle. (Ken McNAMARA, 1999, p.1-4)
In fact, neoteny , i.e. the conservation in adults of embryonic or juvenile biological structures , appears to be a truer evolutive process . It is also of course related with heterochrony.