Monkeys are just like the vast majority of human beings when it comes to sex - when they go ape, they want privacy. Among long-tailed mac-aques, the urge for hanky-panky was dampened when they were being watched by other monkeys, according to an experiment reported in the journal Behavioral Ecology and Sociobiology . Scientists from the Biomedical Primate Research Centre in the Netherlands monitored 15 female and seven male macaques in an enclosure for four months. They installed everything for perfect mating - the simian equivalents of Barry White, satin sheets and mirrored ceilings. The monkeys had tyres and ladders for courting rituals and even a swimming pool. But the animals' main requirement was a quiet spot, to avoid interference from other monkeys, especially dominant alpha males. "By concealing sexual behaviour, females and subordinate males try to reduce harassment from group members," scientist Anna Overduin-de Vries said.