18 JUL 2011 by ideonexus
Ontogeny Recapitulates Phylogeny
The similarity between different vertebrate embryos is indeed remarkable. Since the early 1800s, embryologists have been struck by the parallel between early development in various animal species and their evolutionary relationship, a resemblance conveniently abbreviated by the saying "ontogeny recapitulates phylogeny." Of course, each of us does not really pass through a "lizard" stage on our way to a fully developed human form. But it is true that animals who are more closely related in ter...
1 
Living things go through the forms of their ancestors, not specifically but generally, because it is easier for evolution to add a mutation to the end of a complex sequence of developments than to re-engineer earlier in the process.
