According to Palomar College, monkeys evolved from an extinct species known as prosimians during the transition to the Oligocene Epoch, approximately 33.9 million years ago. Monkeys quickly overcame the prosimians, probably resulting in the extinction of the prosimians, and monkeys became the dominant primate species. During the Miocene Epoch, apes began to evolve from monkeys and displaced them as the dominant primate species.
According to the San Diego Zoo, there are two types of monkeys: Old World and New World. Old World monkeys live in Africa, Central and Southern Asia, India and Japan. New World monkeys call Central and South America and Mexico home. Palomar College notes that during the Oligocene Epoch, the continents began to change shape and move away from each other into their current locations. Palomar College also notes that this shift is how the two types of monkeys ended up on opposite sides of the globe and began to distinguish themselves. The changing of the climate during the Miocene Epoch continued this trend of monkey evolution. It was late during the Miocene Epoch, approximately 14 million years ago, that the first common ancestor of humans and apes appeared in southern Europe. The hominid line, a direct ancestor to humans, appeared approximately 6 million years ago in Africa.