From an early age German physiologist Jacques Loeb (1859-1924) was interested in the question of whether or not free will existed. Rather than pursue his interests via a philosophical approach, Loeb used science to address his question. Using biological experiments on a wide range of specimens, including dogs, caterpillars, and marine animals, Loeb concluded that there was not free will. He believed that all animals, including people, operated mechanistically, as a result of physical and chemical reactions to stimuli. He took this position a step further by arguing that, once scientists understood the mechanics of biology, they could ultimately control development.