The
theory of recapitulation, also called the
biogenetic law or
embryological parallelism— often expressed in
Ernst Haeckel's phrase "
ontogeny recapitulates phylogeny"—is a largely discredited biological hypothesis that in developing from embryo to adult, animals go through stages resembling or representing successive stages in the
evolution of their remote ancestors. Since embryos also evolve in different ways, within the field of developmental biology the theory of recapitulation is seen as a historical side-note rather than as dogma.