The theory of division of labor was presented by Henry Miline Edward. In multicellular organisms, cells join together to form different types of tissues, organs and organ systems which carry out various body functions with great success. That is, functional division of labor is of higher order in animals with limbs. In other words, it can be said that for the successful functioning of body functions in animals, functional division of labor is necessary and to make this functional division of labor more and more successful in animals, the evolution of cells from tissues and from tissues to organs and organ systems must have taken place from the following levels. It has happened in higher class animals.
Functional division of labor leads to 'conservation of energy' in multicellular animals.