All living organisms have evolved from a common ancestor. On the basis of genetic evidence, we can group living things into one of three domains of life, each with a distinct evolutionary history. While the Bacteria and Archaea both have prokaryotic cells, they have distinct evolutionary histories, with Archaea being genetically more closely related to Eukarya than to Bacteria. The domain Eukarya encompasses protists, plants, fungi, and animals, including humans (see Chapter 19).