At that time comparative embryology was the keystone of morphological evolutionary studies, based on Haeckel's recapitulation theory, the idea that an organism during its embryonic development passes through the major stages of the evolutionary past of its species.
Dohrn received his doctorate in 1865 at Breslau under Eduard Grube, and his Habilitation in 1868 at Jena with Rudolf Virchow, Ernst Haeckel and Carl Gegenbaur.