Explanation

The theory of recapitulation is often known as ontogeny recapitulates phylogeny. It was an idea of Etienne Serres in 1824-26. In 1886 Ernst Haeckel proposed that the embryonic development of an individual organism (its ontogeny) followed the same path as the evolutionary history of its species (its phylogeny). It is also called the biogenetic law or embryological parallelism. It was a theory (idea) that tied evolution (the change organisms over time) with embryology (the way organisms develop before they are born). The theory basically stated that before they were born, organisms passed through the developmental stages that look like adult animals of other species, in roughly the same order that these other species split off during evolution