Recapitulation theory of Haeckel
Definition :
The theory says Embryonic stages of higher animals resemble the adults of ancestors. Thus, during embryonic development, an organism presents successive stages of its ancestors.
Introduction :
Ernst Heckel (1811) stated “Ontogeny recapitulates Phylogeny” i.e development of an individual repeats the evolutionary history of the race Generalised features like brain, axial skeleton, spinal cord, vertebrae etc. which are common to all vertebrae etc. which are common to all vertebrates, appear earlier than the special features like hair ( present only in mammals), feather ( in birds only), etc. which distinguish the various vertebrates that appeared later). But later, his explanation was enlightened as “ Biogenetic Law” by Ernst Haeckel and gave rise to “Ontogeny recapitulates Phylogeny” (Where, ontogeny mans development of an individual and phylogeny means, the ancestral history).
Subtitle 1 : Phylogenetic relationship is well exhibited in the embryology
Few examples :
- Tadpole larva of Frog bears distinct fish characters like the presence of gills, gill slits, lateral line sense organs etc. This shows that amphibians have evolved from fish – like ancestor
- Presence of flagellated sperm and water dependency for fertilization like the pteridophytes in same primitive gymnosperm.
- Some primitive gymnosperms like Cyeas and Ginkgo show water dependency for fertilization and presence of flagellated sperm case in pteridophytes in them shows that they have evolved from pteridophytes.