A macaque is definitively a monkey belonging to the genus Macaca. This group of primates represents one of the most geographically widespread and successful groups of non-human primates across the globe. Their specific traits and remarkable adaptability have allowed them to thrive in diverse environments, from tropical forests to snowy mountains.
How Macaques Fit into the Primate Family Tree
Macaques are classified within the Order Primates, the same taxonomic group that includes humans, lemurs, and all other monkeys and apes. Within this order, macaques belong to the family Cercopithecidae, commonly known as the Old World Monkeys. These monkeys are phylogenetically more closely related to apes than they are to New World Monkeys, with the lineage separating from a common ancestor with apes between 25 and 30 million years ago.
A fundamental distinction that defines Old World Monkeys is their physical structure, particularly their non-prehensile tails, meaning they cannot use their tails to grasp or hold objects. Their nostrils are also narrowly spaced and point downward, a characteristic known as catarrhine. Furthermore, Old World Monkeys possess ischial callosities, which are hardened, thickened patches of skin on their buttocks that allow them to sit comfortably on tree branches or the ground for extended periods.
The family Cercopithecidae is further divided into two subfamilies. Macaques fall into the Cercopithecinae subfamily, alongside baboons and mandrills. This classification differentiates macaques from the tailless, larger-brained apes of the family Hominidae.
Distinctive Physical Traits of the Macaca Genus
Macaques are generally robust primates with a stocky build, possessing forelimbs and hindlimbs that are approximately the same length. This limb proportion makes them equally adept at moving on all fours on the ground, a behavior termed semi-terrestrial, and climbing in trees. Their fur color typically ranges through various shades of brown or black, though facial features and color can differ significantly between species.
A highly specific anatomical feature of the macaque genus is the presence of large cheek pouches, which are elastic pockets inside their mouths. These pouches function as temporary storage containers, allowing the macaque to quickly gather and secure a large quantity of food, like fruit and seeds, before retreating to a safer location to eat. This foraging strategy is an important adaptation for survival in environments where competition is high.
Tail length is perhaps the most visually variable trait across the twenty-plus species of macaques. Some species, such as the Long-tailed macaque (Macaca fascicularis), have a lengthy tail that aids in balance, while others possess a very short, vestigial tail. The Barbary macaque (Macaca sylvanus) is notable for being completely tailless, despite remaining a true monkey.
Dentally, macaques, like all Old World Monkeys, have bilophodont molars. These molars feature two transverse ridges on the grinding surface, adapted for their omnivorous diet.
Global Distribution and Species Diversity
The genus Macaca boasts the greatest geographic distribution of any non-human primate, demonstrating remarkable ecological flexibility. Their natural range spans across nearly all of Asia, extending from Japan and the Indian subcontinent to Southeast Asia. A few species also inhabit areas outside of Asia, notably the Barbary macaque, which is native to North Africa and has a single European population in Gibraltar.
Currently, there are over 20 recognized species within the Macaca genus, each adapted to a unique habitat. This diversity allows them to inhabit a wide range of environments, including tropical rainforests, arid mountains, and even snowy temperate zones. The Japanese macaque (Macaca fuscata), often called the Snow Monkey, is a prime example, capable of surviving in areas where temperatures regularly drop below freezing.
Other well-known species include the Rhesus macaque (Macaca mulatta), which has the largest native range of all non-human primates, found across 11 Asian countries. The adaptability of the genus is evident in their ability to coexist with humans, often thriving in urban or semi-urban environments where they forage for food.