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Gibbons () are apes in the family Hylobatidae . The family historically contained one genus, but now is split into four genera and 17 species. Gibbons occur in tropical and subtropical rainforests from eastern Bangladesh and northeast India to southern China and Indonesia (including the islands of Sumatra, Borneo, and Java). Also called the lesser apes, gibbons differ from great apes (chimpanzees, bonobos, gorillas, orangutans, and humans) in being smaller, exhibiting low sexual dimorphism, in not making nests, and in certain anatomical details in which they superficially more closely resemble monkeys than great apes do, but like all apes, gibbons are tailless. Gibbons also display pair-bonding, maintaining the same mate for life, unlike most of the great apes (this has been disputed by Palombit and others, who have found that gibbons might be socially monogamous, with occasional "divorce", but not sexually monogamous〔Reichard, U. (1995) “Extra-pair copulations in a monogamous gibbon (Hylobates lar).” Ethology, vol. 100, no2, pp. 99–112 〕). Gibbons are masters of their primary mode of locomotion, brachiation, swinging from branch to branch for distances of up to , at speeds as high as . They can also make leaps of up to , and walk bipedally with their arms raised for balance. They are the fastest and most agile of all tree-dwelling, nonflying mammals. Depending on species and sex, gibbons' fur coloration varies from dark to light brown shades, and any shade between black and white. Seeing a completely "white" gibbon is rare. Gibbon species include the siamang, the white-handed or lar gibbon, and the hoolock gibbons. ==Evolutionary history== Whole genome molecular dating analyses indicate that the gibbon lineage diverged from that of great apes around 16.8 million years ago (Mya) (95% confidence interval: 15.9 – 17.6 Mya; given a divergence of 29 Mya from monkeys). Adaptive divergence associated with chromosomal rearrangements led to rapid radiation of the four genera 5-7 million years ago. Each genus comprises a distinct, well-delineated lineage, but the timing and sequence of divergence among these genera remains unresolved, even with whole genome data, due to extensive incomplete lineage sorting.〔〔Matsudaira K, Ishida T (2010) Phylogenetic relationships and divergence dates of the whole mitochondrial genome sequences among three gibbon genera. Mol. Phylogenet. Evol.〕 At the species level, estimates from mitochondrial DNA genome analyses suggest that ''Hylobates pileatus'' diverged from ''H. lar'' and ''H. agilis'' around 3.9 Mya, and ''H. lar'' and ''H. agilis'' separated around 3.3 Mya.〔 Whole genome analysis suggests divergence of ''Hylobates pileatus'' from ''Hylobates moloch'' 1.5-3.0 Mya.〔 The extinct ''Bunopithecus sericus'' is a gibbon or gibbon-like ape which, until recently, was thought to be closely related to the hoolock gibbons.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「gibbon」の詳細全文を読む スポンサード リンク
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