In the 17th century, scientists began to see how the organic body worked and came to understand the mechanics of life. At the same time, philosophers were developing the idea that the soul existed separately from the body. While Descartes had argued against the existence of an immortal soul, his ideas about mind and matter remained influential. Animals were still considered mindless, however, because they could not think rationally as humans did. This led many scientists to assume that animals lacked minds altogether.
In the Cartesian view, animals are thought to simply be a part of the physical world and are subject to physical laws as machines. Philosophers derived that animals are similar to ingenious automata that exhibit similar behaviors as animals with patently no mind or consciousness.