Homology

'Homology' as a concept became increasingly elusive during the course of the 20th century. The central debates and controversies concern both fundamental definitions and the nature of the criteria by which homology is judged. Attempts to move away from comparative morphology to ideas based on developmental pathways have tended to founder on the fact that developmental pathways evolve and that similar cells or tissues or structures in animals will often have different developmental origins. The use of information about conserved molecules in seemingly conserved developmental processes has also proven controversial. In molecular biology, the use of the term 'homology' has g…