Monogamy and duetting in an Old World monkey

THE first monogamous mating system among Old World monkeys has been discovered in the Mentawai langur, Presbytis potenziani. The only known monogamous anthropoid primates were the Old World gibbons (Hylobates spp.)¹ and a few New World monkeys^2-4. Reproductive groups of all known Old World monkeys, represented by approximately 85 species, are either polygamous or promiscuous⁵.