» For other uses, see Simian (disambiguation); and distinguish from Simien. The simians (infraorder Simiiformes) are the "higher primates" familiar to most people: the monkeys and the apes, including humans. Simians tend to be larger than the "lower primates" or prosimians. Classification and evolution The simians are split into three groups. The New World monkeys in Platyrrhini parvorder split from the simian line about 40 million years ago (mya), leaving the Catarrhini parvorder occupying the… (More on Simian)