Reproduction, Metabolism, and homeostasis are all the result of multiple organs communicating and organizing in a manner that allows for the specification of certain cells to do certain things. Because we have so many organs to do different things, the cells can focus on doing one function as opposed to one cell having to do all of the functions we can do today. We evolved from single cell organisms into what we are today through millions of years of adaptation and the passing on of genes that are the best fit for the environment.
