No one can truly pinpoint when people began to study animal anatomy. Many scientists believe it came from all the religious sacrifices of animals and how these structures compared to humans. Early Egyptians, and other cultures, also had to have some crude internal (for example, organs and veins) knowledge of certain animals, especially those creatures that were embalmed and buried with the human dead. One of the first people who probably knew about anatomy of animals was Greek philosopher Aristotle (c. 330 B.C.E.), who dissected animals and described many of their physical attributes. One positive outcome of such dissections, though, was that they eventually led to more knowledge about human anatomy.