Ontogeny is the scientific belief pertaining to the development of embryos. The idea behind it is that scientists can trace the evolutionary history of organisms through its ancestral characteristics. The belief is that ancestral characters of organisms will more likely than not, be preserved in an organisms development. The idea is better visualized in the following manner.
“both chick and human embryos go through a stage where they have slits and arches in their necks that are identical to the gill slits and gill arches of fish. This observation supports the idea that chicks and humans share a common ancestor with fish. Thus, developmental characters, along with other lines of evidence, can be used for constructing phylogenies.” (“Ontology and Phylogeny”, n.d.)
On the other hand, Phylogeny is defined by scientists as “the history of the evolution of a species or group, especially in reference to lines of descent and relationships among broad groups of organisms. “ (“phylogeny”, n.d.) Phylogeny is basically reliant on the theory that plants or animals all descend from common ancestors. However, due to the lack of scientific basis for this theory to be proven as true, since most of the ancestors of life on the planet are already extinct and the fossils on record are few and far between, this theory is based solely on direct evidence.
Having now defined what Ontogeny and Phylogeny are in relation to the evolution of man, we may now coherently discuss as to whether Ontogeny recapitulates Phylogeny. Most scientists do not agree with the ORP theory and reject the thought based upon the embryological evidence for evolution. Basically, if we look at a man and a chick, we will see that both fetuses have gills and slits in the neck. Therefore, both species stemmed from a fish-like existence. However, the animal and the man never turned into fishes before turning into men and chicks.