Macaques

The macaques are successful Old World monkeys (family Cercopithecidae)that are members of the genus Macaca, of which there are some 20 species. Macaques are the most wide-ranging primate species except for humans. One species, M.sylvanus or the Barbary macaque, is found in Morocco, Algeria, and Gibraltar. The other species are found from Afghanistan to Beijing and from Sri Lanka through Indonesia to Japan. M.mulatta, or the rhesus macaque, has the widest distribution and is found from eastern Afghanistan through northern India to southern Vietnam and southern China. Other macaques have a more limited distribution, including those of Sulawesi and Indonesia and M. silenus (the lion-tailed macaque), which is found only in the Western Ghats of India.

Macaques are small to medium-sized monkeys, most of which have a brown or grayish pelage, although a few macaques such as M.nigra have black hair. They have naked faces and ears, and their tails vary in length from nearly no tail (e.g., M. arctoides)[Page 1509]to tails that are the length of the body or longer (e.g.,M. fascicularis). Macaques are quadrupedal and basically arboreal, although some species such as M. mulatta spend more than half of their time on the ground. Other traits of macaques include cheek pouches and ischial callosities or sitting pads. Their diet is composed mainly of vegetation (fruit, leaves, flowers, and bark) and insects and other invertebrates.

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The fossil record of the Old World monkeys is known from the early and middle Miocene, with a group of remains recognized as belonging to two African genera: Victoriapithecus and Prohylobates. These two genera preceded the separation of the two extant subfamilies of Old World monkeys: Colobinae and Cercopithecinae. The Old World monkeys shared a common ancestor with the hominoids (i.e., the apes), diverging during the late Oligocene or early Miocene. Overall, monkey fossils from the Miocene are rather scarce compared with the numerous fossil hominoids. Macaques appear in the fossil record during the late Miocene and early Pliocene, first in Africa and subsequently in Europe and Asia. Today only 1 macaque species still inhabits North Africa (M. sylvanus), 19 species live in Asia, and none is found in Europe. After 5 million years of successful evolution, many species of macaques are facing extinction due to human activities. According to the International Union for Conservation of Nature and Natural Resources, 57% of macaque species are either endangered or vulnerable, and if one adds the near threatened and conservation-dependent species, the number increases to nearly 100% of the macaques potentially facing extinction. Human greed, overpopulation, and lack of compassion are the reasons why the number of macaques is declining worldwide.

The basic macaque social system is called the multimale, multifemale troop in which females remain in their natal troop and males move to a non-natal troop or become solitary. The core of the multimale, multifemale troop is the matrafocal units composed of related females. Males and females have dominance hierarchies, but males (being larger than females and possessing larger canine teeth) are dominant to females. Rank among females is often inherited from their mothers. There is, however, some variation in this basic social system. For example, in rhesus and Japanese macaques, the males are consistently forced out of their natal troops when they reach sexual maturity around 5 years of age, but bonnet macaque males have been known to remain in their natal troops. The dominance hierarchy is generally stronger in those troops fed by humans than in those that survive by foraging on natural vegetation.

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