Developmental Homology

Abstract

Homology is the fundamental determinant of the sameness of biological charac- ters or traits. When two characters stand in a relation ofhomology, they belong to the same character kind. For example, the eyes of humans and birds are homologous as vertebrate eyes – that is, they are the same kind of character: vertebrate eyes. Although the concept of homology originated in pre-Darwinian comparative anatomy, it was subsequently revealed to be an evolutionary phenomenon caused by common descent. Contemporary investigators work roughly within the following generic evolutionary conception of homology: Homology: Two characters in distinct organisms or taxa are homologous if they are genealogically connected by continuous descent from a common ancestor that had the same character.