The monkeys of Africa and Asia form the family Cercopithecidae, one of the main divisions of the anthropoid primates. Unlike their prosimian relatives, the anthropoids are almost universally adapted to life in the daytime, which brings fundamental changes in their morphology, ecology and behavior.
Generally larger than their Neotropical cousins, Old World monkeys have nostrils that are closer together and directed downward, a condition reflected in an alternate name for the group, the catarrhines. They have longer hind limbs than front limbs, flattened nails on their fingers and toes (much like human fingernails), long tails and ischial callosities – or toughened pads of flesh on their rump that support them while sitting.
They also have acute vision, crucial to daily life. Their ability to focus very closely on nearby objects helps these monkeys identify food and move high in the forest canopy.
Cheek-Pouches & Leaf-Eating
Within the family Cercopithecidae, there is another major division, this time into two subfamilies: the Cercopithecinae, the cheek-pouched monkeys, and the Colobinae, the leaf-eating monkeys.
The first of these subfamilies, the Cercopithecinae, includes a tremendous variety of color and form: the guenons, the patas monkeys, the macaques, the mangabeys, and the baboons, drills and mandrills.
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The monkeys in the Colobinae, including the African colobus monkeys and the Asian langurs, specialize on leaves and other plant materials for their diet – a plentiful resource in the tropical forest, but low in energy and requiring a heavy, multi-part stomach to ferment them.
Where They Live
As a group the Old World monkeys are both arboreal and terrestrial. Different species can inhabit a wide variety of ecosystems, exploit an array of food sources and live in often intricate social situations.
Some species – in particular the baboons, langurs and macaques – are comfortable living near humans and will often raid crops, frequently leading to unfortunate encounters between monkeys and farmers. The availability of food has an enormous impact on when certain species will reproduce. Vervet monkeys in captivity (well and predictably fed) tend to produce offspring every two to three years, while those in the wild (surviving on an uncertain diet) may conceive only once every five years.
How They Live
Among Old World monkeys, group life is the norm; they have a keen social intelligence and an ability to assess their peers and rivals. They are capable of nuanced communication between individuals with an expanded repertoire of sounds and facial displays.
Group living has its drawbacks: there is competition for food, a greater chance of contracting disease or parasites, and groups are more obvious to predators. But these negatives are balanced by new positives: more eyes and ears on the alert for danger and more allies to defend a territory and nurture the young.
Threats to Old World Monkeys
Increases in human population in both Africa and Asia have heightened the threats to Old World Monkeys. Resources have become more scarce – for both human and primate communities.
Heavy logging is accelerating the destruction of natural habitat. Forestry concessions are granted within once-pristine expanses of forest, exposing the wildlife to unprecedented levels of hunting, from both local people and outside laborers. Primates are a major component of the bushmeat trade, and they are hunted with intensity in West and Central Africa. This commercialized industry supplies the loggers with sustenance and the markets with high-priced delicacies. The unsustainable hunting of many larger-bodied primates, such as guenons and colobus monkeys, is reaching disastrous proportions.
LEARN MORE: Discover the many threats primates are facing, including habitat loss and hunting.
The urgent warnings have long since been sounded, and many species have not been seen for years or decades. Only intensive, on-the-ground conservation action, combined with far-reaching campaigns for public awareness, will help stem the tide of impending extinctions that threatens many African and Asian primates.