Hox genes, homology and axis formation-The application of morphological concepts to evolutionary developmental biology

Furthermore, it is demonstrated, that spatial and temporal similar gene expression patterns, indicating similar molecular genetic mechanisms, were interpreted as an analytical criterion of homology, offering the possibility to identify similar structures. In contrast to this, the evolutionary developmental biolgists have not developed a causal-analytically extended concept of shape, from which a causal-analytical concept of homology could be deduced. Instead, the homology concept from evolutionary morphology is used.