But archetypal claims for homology across distantly related phyla raise far more serious theoretical problems. No shockwaves attended the discovery of common genetic and developmental pathways for the serial array of arthropod appendages, despite their functional differentiation as antennae, mouth parts, legs, genital claspers, etc. But the discovery that homological pathways also persist among animal phyla that have evolved independently since the Cambrian explosion has reversed previous certainties and brought Geoffroy’s despised archetypal theories into renewed respectability.
