Original: In 1866 , the German zoologist Ernst Haeckel proposed that the embryonic development of an individual organism ( its ontogeny ) followed the same path as the evolutionary history of its species ( its phylogeny ) .
Simplified: In 1886 Ernst Haekel proposed that the embryonic development of an individual organism ( its ontogeny ) followed the same path as the evolutionary history of its species ( its phylogeny ) .