If you're in the market for a monkey butler, look no further than the capuchin. Named for their resemblance to the Catholic friars, in earlier times these monkeys have worked alongside organ grinders and as jockeys in greyhound races. Today, they often serve as domestic assistants to the disabled.
Capuchins are widely regarded as the most intelligent of New World monkeys. The tufted capuchin has been observed using tools and engaging in long-term planning. In 2005, Yale economist M. Keith Chen introduced a group of tufted capuchins to the concept of currency; and watched as the monkeys learned to exchange coins for grapes or Jell-O cubes. The monkeys seemed to respond rationally to price shocks and irrationally to gambling opportunities, prompting Chen to tell the New York Times that the monkeys were "statistically indistinguishable from most stock-market investors."
According to the Times, Chen was forced to alter his currency experiment when he spotted two monkeys engaging in prostitution.
