Fins and Limbs

Abstract

This chapter focuses on the evolutionary processes underlying fins and limbs. Some of the most momentous periods in the history of the human lineage involved evolutionary changes to the paired appendages. Modifications of the hind limb and foot were key during the evolution of bipedal locomotion and the erect posture that is characteristic of humans. Evolutionary biologists have devoted a lot of time and effort in studying both the origin of paired fins and the transformation of fins to tetrapod limbs. The chapter first considers fossil evidence and recent developmental evidence on the origin of paired fins before discussing the fin–limb transition. It also reflects on the nature of character identity and suggests that the origin and evolution of fins and limbs reveal an intriguing pattern of serial homology, identity, and innovation that contradicts the notion of hierarchical homology.