Monkeys are a diverse group of primates, with hundreds of species distributed across the globe. Their natural habitats are largely confined to tropical and subtropical regions, where they thrive in environments offering dense vegetation and consistent warmth. This geographic restriction is a result of their evolutionary history and physiological adaptations.
The Fundamental Geographic Split
The worldwide distribution of monkeys is fundamentally divided into two distinct groups: the Platyrrhines and the Catarrhines. These two lineages evolved independently on different landmasses following a geological separation millions of years ago. Platyrrhines, or “broad-nosed” primates, developed in the Americas, while Catarrhines, or “down-nosed” primates, evolved in Africa and Asia.
The split occurred approximately 35 to 40 million years ago. Ancestors of New World monkeys are thought to have rafted across the Atlantic Ocean from Africa to South America. This geographical isolation led to significant differences in their physical characteristics, such as the shape of their noses, the number of teeth, and the presence of prehensile tails in many American species.
Distribution in Central and South America
Monkeys in the Americas, the Platyrrhines, are found exclusively in the tropical regions stretching from Southern Mexico down through Central and South America. Their range extends through all of the Amazon basin, covering vast territories in countries like Brazil, Peru, Ecuador, and Colombia. They are primarily arboreal, meaning they spend most of their lives in the trees, a lifestyle supported by the dense, three-dimensional structure of their habitat.
The main habitats for American monkeys are the lowland tropical rainforests and the higher-altitude cloud forests. This environment has fostered a wide array of species, many of which possess prehensile tails that function as a powerful fifth limb for grasping branches. Examples of species found only in the Americas include the loud-calling Howler monkeys, the highly acrobatic Spider monkeys, the intelligent Capuchin monkeys, and the smaller, clawed Marmosets and Tamarins.
Distribution Across Africa and Asia
The Catarrhines, which include the monkeys of Africa and Asia, have a far more expansive and varied distribution than their American relatives. In Africa, their range extends across the sub-Saharan continent, from the dense equatorial rainforests to the open savannas and rocky areas. Species like the Mandrill and various Colobus monkeys inhabit the forested regions, while the Baboons are highly successful in the open grasslands and semi-arid environments.
The Asian distribution stretches from the Indian subcontinent and Southeast Asia, reaching as far north as parts of China and Japan. This extensive range includes diverse habitats, such as the tropical jungles of Indonesia and the snowy mountains where the Japanese Macaques use hot springs for warmth. Old World monkeys also exhibit a greater tolerance for human proximity; for example, Rhesus Macaques are commonly found near human settlements across India. One notable population is the Barbary Macaque, the only monkey species found in Europe, residing on the Rock of Gibraltar.