Monkeys are incredibly smart animals and can get into a lot of trouble both in captivity and in their natural habitat. They are also very vocal animals that use different pitches to communicate with other monkeys. They have forward facing eyes and flat noses that help them climb and move on the ground as well as in the trees. They have opposable thumbs that they can use to grab things and are diurnal which means they are active during the day.
Almost all monkey species live in groups called troops, which can contain just a few individuals or thousands. They are highly social animals that form close bonds within their troops and can even show emotions such as love, anger, and sadness. They can be aggressive to other monkeys but also protect the young and old members of their troop. They often have a strict social hierarchy with dominant males having greater access to females and food. They mate seasonally, with the season varying between species. For example, Guianan squirrel monkeys in South America mate between September and November and give birth in February and April after a gestation period of 160 to 170 days.
Their resemblance to humans has cost monkeys dearly, with a number of species being captured and held in zoos and labs for research and as pets. While defenders of animal testing say that it has helped us cure diseases, most monkey rights advocates would argue that they should be kept in the wild where they can be safe from poachers and other threats.