The macaques constitute a genus of Old World monkeys of the subfamily Cercopithecinae. The 23 species of macaques are widespread over the Old World, especially Asia. Macaques are principally frugivorous, although their diet also includes seeds, leaves, flowers, and tree bark, and some, such as the crab-eating macaque, subsist on a diet of invertebrates and occasionally small vertebrates. All macaque social groups are arranged around dominant, matriarchal females. The Assam macaque has a yellowish-grey to dark brown pelage. The facial skin is dark brownish to purplish. The head has a dark fringe of hair on the cheeks directed backwards to the ears. The hair on the crown is parted in the middle. The shoulders, head and arms tend to be paler than the hindquarters, which are greyish. The tail is well-haired and short. It is classified as Near Threatened by IUCN.