Monkey sizes range from the tiny pygmy marmoset, who is about 4.5 inches tall, to the mandrill at well over 3 feet in height. Monkeys are generally arboreal and are excellent climbers, with some notable ground-dwelling exceptions, such as macaques and baboons. Almost all monkeys are diurnal and live in troops of up to many hundreds, with no permanent shelters.

The first discovery of chimpanzee tool use was made by Jane Goodall in October of 1960 as she watched a chimpanzee deliberately take the leaves off a stem and use it to go termite “fishing.” Subsequent research has revealed extensive tool construction and use among chimpanzees, including making spears to hunt small mammals, using leaves for sponges or napkins, using rocks as anvils and hammers to crack open nuts, and employing selected branches to open up beehives. Some keep favorite “tool kits,” and teach tool usage from one generation to the next. Archeological research has uncovered chimpanzee stone tools used over 4,000 years ago.

Chimpanzees communicate with non-verbal and verbal expression, and some have even learned to use computer graphics and American Sign Language. Washoe, a famous chimpanzee, upon first seeing a swan, called it a “water bird.”

Although strictly prohibited in the United States, monkeys are kept as pets in many places around the world, and are sometimes trained to work in civilized settings. Pig-tailed macaques have been used to pick coconuts in Thailand and Malaysia. The Kayabukiya Tavern in Tokyo used a pair of Japanese macaques to serve customers. Surprising to some, monkeys remain a key source of bushmeat in parts of the world. Monkeys may also be killed by the score in “monkey drives” if they are seen as threats to human agriculture.