Involution of Organs

the reduction in the number of homologous organs over the course of animal evolution. The Soviet scientist V. A. Dogel’ conducted research between 1930 and 1950 that established the involution of organs as an important morphophysiological principle in the evolution of multicellular animals. In the evolution of a species, new organs usually originate in groups and are spatially disordered. As phylogeny continues, the number of organs decreases, and the remaining organs become progressively differentiated.