Gibbon

Gibbons[1][2]
Temporal range: Miocene–Recent
Lar Gibbons (Hylobates lar)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Superfamily: Hominoidea
Family: Hylobatidae
Gray, 1870
Genera

Hylobates
Hoolock
Nomascus
Symphalangus
Distribution in Southeast Asia

Gibbons are apes in the family Hylobatidae ( /ˌhaɪlɵˈbeɪtɨdiː/). The family is divided into four genera based on their diploid chromosome number: Hylobates (44), Hoolock (38), Nomascus (52), and Symphalangus (50).[2][3] The extinct Bunopithecus sericus is a gibbon or gibbon-like ape which, until recently, was thought to be closely related to the hoolock gibbons.[2] Gibbons occur in tropical and subtropical rainforests from northeast India to Indonesia and north to southern China, 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. Gibbons also display pair-bonding, unlike most of the great apes. Gibbons are masters of their primary mode of locomotion, brachiation, swinging from branch to branch for distances of up to 15 m (50 ft), at speeds as high as 56 km/h (35 mph). They can also make leaps of up to 8 m (26 ft), and walk bipedally with their arms raised for balance. They are the fastest and most agile of all tree-dwelling, non-flying mammals.[4]

Depending on species and gender, gibbons' fur coloration varies from dark to light brown shades, and anywhere in between black and white. It is rare to see a completely white gibbon.

Gibbon species include the siamang, the white-handed or lar gibbon, and the hoolock gibbons. The siamang, which is the largest of the sixteen species, is distinguished by having two fingers on each foot stuck together, hence the generic and species names Symphalangus and syndactylus.[5]

Contents

Anatomy

One unique aspect of gibbon physiology is that the wrist is composed of a ball and socket joint, allowing for biaxial movement. This greatly reduces the amount of energy needed in the upper arm and torso, while also reducing stress on the shoulder joint. Sometimes when a gibbon is swinging, their wrist will naturally dislocate until the gibbon finishes its swing. Gibbons also have long hands and feet, with a deep cleft between the first and second digits of their hands. Their fur is usually black, gray, or brownish, often with white markings on hands, feet, and face. The male gibbon will sometimes end up with some dark patches in the white to show it is a suitable choice for mating. Some species have an enlarged throat sac, which inflates and serves as a resonating chamber when the animals call. This structure is enormous in a few species, equaling the size of the animal's head.

Gibbon skulls and teeth resemble those of the great apes, and their noses are similar to those of all catarrhine primates. The dental formula is Upper: 2.1.2.3, lower: 2.1.2.3 [6]

Behavior

Gibbons are social animals. They are strongly territorial, and defend their boundaries with vigorous visual and vocal displays. The vocal element, which can often be heard for distances of up to 1 km, consists of a duet between a mated pair, their young sometimes joining in. In most species males, and in some also females, sing solos that attract mates as well as advertise their territory.[7] If a male and female like one another's song they will find the other gibbon and do a short mating dance followed by a vigorous mating ritual that lasts three days and they will mate about five hundred times in this time period. The songs can make them an easy find for poachers who engage in the illegal wildlife trade and in sales of body parts for use in traditional medicine. The song can be used to identify not only which species of gibbon is singing but the area it is from.[8]

The gibbons' ball-and-socket joints allow them unmatched speed and accuracy when swinging through trees. Nonetheless, their mode of transportation can lead to hazards when a branch breaks or a hand slips, and researchers estimate that the majority of gibbons suffer bone fractures one or more times during their lifetimes.[4]

Status

Most species are threatened or most endangered, most importantly from degradation or loss of their forest habitat.

Classification


Evolution

The dating of the evolution of these genera has been difficult.[10] The best current estimates place Nomascus diverging from the other genera at ~8 million years ago (Mya); Symphalangus and Hylobates diverging at 7 Mya. At the species level Hylobates pileatus diverged from Hylobates lar and Hylobates agilis at 3.9 Mya; and Hylobates lar and Hylobates agilis separated at 3.3 Mya.

Hybrids

Many gibbons are hard to identify based on fur coloration and are identified either by song or genetics.[11] These morphological ambiguities have led to hybrids in zoos. Zoos often receive gibbons of unknown origin and therefore rely on morphological variation or labels that are impossible to verify to assign species and subspecies names, so it is common for separate species of gibbons to be misidentified and housed together. Interspecific hybrids, hybrids within a genus, also occur in wild gibbons where the ranges overlap.[12]

In traditional Chinese culture

The sinologist Robert van Gulik concluded that gibbons were widespread in Central and Southern China until at least the Song Dynasty, and furthermore, based on an analysis of references to primates in Chinese literature and their portrayal in Chinese paintings, that the Chinese word yuán (猿) referred specifically to gibbons until they were extirpated throughout most of the country due to habitat destruction (circa 14th century). In modern usage, however, yuán is a generic word for ape. Early Chinese writers viewed the "noble" gibbons, gracefully moving high in the treetops, as the "gentlemen" (jūnzǐ, 君子) of the forests, in contrast to the greedy macaques, attracted by human food. The Taoists ascribed occult properties to gibbons, believing them to be able to live a several hundred years and to turn into humans.[13]

Gibbon figurines as old as from the 3-4th century BCE (the Zhou Dynasty) have been found in China. Later on, gibbons became a popular object for Chinese painters, especially during the Song Dynasty and early Yuan Dynasty, when Yì Yuánjí and Mùqī Fǎcháng excelled in painting these apes. From Chinese cultural influence, the Zen motif of the "gibbon grasping at the reflection of the moon in the water" became popular in Japanese art as well, even though gibbons have never occurred naturally in Japan.[14]

References

Notes
  1. ^ a b Groves, C. (2005). Wilson, D. E., & Reeder, D. M, eds. ed. Mammal Species of the World (3rd ed.). Baltimore: Johns Hopkins University Press. pp. 178–181. OCLC 62265494. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=12100752. 
  2. ^ a b c Mootnick, A.; Groves, C. P. (2005). "A new generic name for the hoolock gibbon (Hylobatidae)". International Journal of Primatology 26 (26): 971–976. doi:10.1007/s10764-005-5332-4. 
  3. ^ a b Geissmann, Thomas (December 1995). "Gibbon systematics and species identification" (PDF). International Zoo News 42: 467–501. http://gibbons.de/main/papers/pdf_files/1995gibbon_systematics_big.pdf. Retrieved 2008-08-15. 
  4. ^ a b David Attenborough, Life of Mammals, Episode 8: Life in the Trees. BBC Warner, 2003.
  5. ^ Geissmann, T. (2011). "Typical Characteristics". Gibbon Research Lab. http://gibbons.de/main/index.html. Retrieved 17 August 2011. 
  6. ^ Myers, P. 2000. Family Hylobatidae, Animal Diversity Web. Accessed April 05, 2011-04-05.
  7. ^ Clarke E, Reichard UH, Zuberbühler K (2006). Emery, Nathan. ed. "The Syntax and Meaning of Wild Gibbon Songs". PLoS ONE 1 (1): e73. doi:10.1371/journal.pone.0000073. PMC 1762393. PMID 17183705. http://dx.plos.org/10.1371/journal.pone.0000073. 
  8. ^ [1] Recognizing gibbons from their regional accents
  9. ^ Thomas Geissmann. "Gibbon Systematics and Species Identification" (web version). Ch.3: "Adopting a Systematic Framework" Retrieved: 2011-04-05.
  10. ^ Matsudaira K, Ishida T (2010) Phylogenetic relationships and divergence dates of the whole mitochondrial genome sequences among three gibbon genera. Mol. Phylogenet. Evol.
  11. ^ Tenaza, R. (1984). "Songs of hybrid gibbons (Hylobates lar × H. muelleri)". American Journal of Primatology 8 (3): 249–253. doi:10.1002/ajp.1350080307. 
  12. ^ Sugawara, K. (1979). "Sociological study of a wild group of hybrid baboons between Papio anubis and P. hamadryas in the Awash Valley, Ethiopia". Primates 20 (1): 21–56. doi:10.1007/BF02373827. 
  13. ^ Robert van Gulik, The gibbon in China. An essay in Chinese animal lore. E.J.Brill, Leiden, Holland. (1967). There is a brief summary at [2]
  14. ^ Thomas Geissmann, Gibbon paintings in China, Japan, and Korea: Historical distribution, production rate and context". Gibbon Journal, No. 4, May 2008. (This article includes color reproductions of a large number of gibbon paintings by many artists.)

External links

Extant primate families by suborder
Kingdom Animalia · Phylum Chordata · Class Mammalia · Infraclass Eutheria · Superorder Euarchontoglires
Strepsirrhini
Haplorhini