Human embryo have gills. This shows ontogeny repeats phylogeny. Ontogeny is the life history of an organism while phylogeny is the evolutionary history of the race of that organism. Modern theory of origin of life was propounded by Oparin and Haldane which is based on chemical evolution. Chemical evolution, also called chemogeny, involves the synthesis of simple organic molecules. Miller and Urey experimentally supported Oparin and Haldane theory with the help of stimulation experiment. Analogous organs are those organs which are similar in shape and function but their origin, basic plan and development are dissimilar. Example, wings of butterfly, bird and bat. Such similarities are because of convergent evolution for adaptation to a common condition.