ABSTRACT. In a captive group of Japanese monkeys, a juvenile female spontaneously began standing poles against a concrete wall and climbing up them in 1983. By 1987, 3 juvenile females out of 39 monkeys had acquired the behavior. They stood rather heavy poles, weighing 2.6 kg, against the wall and climbed up them without training. At the top of the poles, they often explored the smooth wall by licking or touching it.