Monkey lovers looking to purchase a marmoset, macaque, tamarin, squirrel monkey, or any other primate species as petsitting is important you do the necessary research to make sure you're ready for this lifelong commitment. The majority of monkeys live for a very long time ranging from 15-25 years for marmosets (or finger monkeys .Pygmy marmoset as some people like to call them) and up to 45 years for capuchins. Unlike in the wild, monkeys kept as pets often live much longer since there are no predators in our homes and we have access to monkey vets.