Gibbon
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Gibbons () are
ape Apes (collectively Hominoidea ) are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and as well as Europe in prehistory), which together with its sister g ...
s in the
family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Hylobatidae (). The family historically contained one
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
, but now is split into four extant genera and 20
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
. Gibbons live in subtropical and
tropical rainforest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equatori ...
from eastern
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
to
Northeast India , native_name_lang = mni , settlement_type = , image_skyline = , image_alt = , image_caption = , motto = , image_map = Northeast india.png , ...
to
southern China South China () is a geographical and cultural region that covers the southernmost part of China. Its precise meaning varies with context. A notable feature of South China in comparison to the rest of China is that most of its citizens are not n ...
and
Indonesia Indonesia, officially the Republic of Indonesia, is a country in Southeast Asia and Oceania between the Indian and Pacific oceans. It consists of over 17,000 islands, including Sumatra, Java, Sulawesi, and parts of Borneo and New Guine ...
(including the islands of
Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
,
Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...
and
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...
). Also called the lesser apes, gibbons differ from
great ape The Hominidae (), whose members are known as the great apes or hominids (), are a taxonomic family of primates that includes eight extant species in four genera: '' Pongo'' (the Bornean, Sumatran and Tapanuli orangutan); ''Gorilla'' (the ...
s ( bonobos, chimpanzees,
gorilla Gorillas are herbivorous, predominantly ground-dwelling great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or fi ...
s,
orangutan Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genu ...
s and
human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, culture, ...
s) in being smaller, exhibiting low
sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...
, and not making nests. Like all apes, gibbons are
tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammal ...
less. Unlike most of the great apes, gibbons frequently form long-term
pair bond In biology, a pair bond is the strong affinity that develops in some species between a mating pair, often leading to the production and rearing of offspring and potentially a lifelong bond. Pair-bonding is a term coined in the 1940s that is freque ...
s. Their primary mode of locomotion, brachiation, involves swinging from branch to branch for distances up to , at speeds as fast as . They can also make leaps up to , and walk bipedally with their arms raised for balance. They are the fastest of all tree-dwelling, nonflying mammals. Depending on the species and sex, gibbons' fur coloration varies from dark- to light-brown shades, and any shade between black and white, though a completely "white" gibbon is rare.


Etymology

The English word "gibbon" is a reborrowing from French and may originally derive from an
Orang Asli Orang Asli (''lit''. "first people", "native people", "original people", "aborigines people" or "aboriginal people" in Malay) are a heterogeneous indigenous population forming a national minority in Malaysia. They are the oldest inhabitants of ...
word.


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
Old World monkey Old World monkey is the common English name for a family of primates known taxonomically as the Cercopithecidae (). Twenty-four genera and 138 species are recognized, making it the largest primate family. Old World monkey genera include baboons ...
s). Adaptive divergence associated with chromosomal rearrangements led to rapid radiation of the four genera 5–7 Mya. Each genus comprises a distinct, well-delineated lineage, but the sequence and timing of divergences among these genera has been hard to resolve, even with whole genome data, due to radiative speciations and extensive
incomplete lineage sorting Incomplete lineage sorting, also termed hemiplasy, deep coalescence, retention of ancestral polymorphism, or trans-species polymorphism, describes a phenomenon in population genetics when ancestral gene copies fail to coalesce (looking backwards i ...
. An analysis based on
morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
suggests that the four genera are ordered as (''Symphalangus'', (''Nomascus'', (''Hoolock'', ''Hylobates''))). A coalescent-based species tree analysis of genome-scale datasets suggests a phylogeny for the four genera ordered as (''Hylobates'', (''Nomascus'', (''Hoolock'', ''Symphalangus''))). 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 ''H. pileatus'' from ''H. moloch'' 1.5–3.0 Mya. The extinct ''
Bunopithecus sericus ''Bunopithecus'' is an extinct genus of primate represented by one species, ''Bunopithecus sericus'', a gibbon or gibbon-like ape. Its remains were first discovered in Sichuan, China, in strata from the Middle Pleistocene. Although the three hoo ...
'' is a gibbon or gibbon-like ape, which until recently, was thought to be closely related to the hoolock gibbons.


Taxonomy

The family is divided into four
genera Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomenclat ...
based on their
diploid Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively ...
chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
number: '' Hylobates'' (44), ''
Hoolock The hoolock gibbons are three primate species of genus ''Hoolock'' in the gibbon family, Hylobatidae, native to eastern Bangladesh, Northeast India, Myanmar, and Southwest China. Description Hoolocks are the second-largest of the gibbons, after ...
'' (38), ''
Nomascus ''Nomascus'' is the second-most speciose genus of gibbons (family Hylobatidae). Originally, this genus was a subgenus of ''Hylobates'', and all individuals were considered one species, ''Hylobates concolor''. Species within ''Nomascus'' are cha ...
'' (52), and ''
Symphalangus The siamang (, ; ''Symphalangus syndactylus'') is an arboreal, black-furred gibbon native to the forests of Indonesia, Malaysia, and Thailand. The largest of the gibbons, the siamang can be twice the size of other gibbons, reaching in height, a ...
'' (50). Also, three extinct genera currently are recognised: ''
Bunopithecus ''Bunopithecus'' is an extinct genus of primate represented by one species, ''Bunopithecus sericus'', a gibbon or gibbon-like ape. Its remains were first discovered in Sichuan, China, in strata from the Middle Pleistocene. Although the three hoo ...
'', ''
Junzi A junzi ( or "Son of the Monarch") is a Chinese philosophical term often translated as "gentleman," "superior person",Sometimes "exemplary person". Paul R. Goldin translates it "noble man" in an attempt to capture both its early political and la ...
'', and '' Yuanmoupithecus''. Family Hylobatidae: gibbons * Genus ''
Hoolock The hoolock gibbons are three primate species of genus ''Hoolock'' in the gibbon family, Hylobatidae, native to eastern Bangladesh, Northeast India, Myanmar, and Southwest China. Description Hoolocks are the second-largest of the gibbons, after ...
'' **
Western hoolock gibbon The western hoolock gibbon (''Hoolock hoolock'') is a primate from the gibbon family, Hylobatidae. The species is found in Assam, Mizoram, and Meghalaya in India, Bangladesh, and Myanmar west of the Chindwin River. Classification Mootnick an ...
, ''H. hoolock'' **
Eastern hoolock gibbon The eastern hoolock gibbon (''Hoolock leuconedys'') is a primate from the gibbon family, Hylobatidae. It is one of three species of hoolock gibbon. This species is found in east of the Chindwin River, such as the Mahamyaing Wildlife Sanctuary, a ...
, ''H. leuconedys'' **
Skywalker hoolock gibbon The Skywalker hoolock gibbon or Gaoligong hoolock gibbon (''Hoolock tianxing'') is an arboreal primate in the gibbon family, Hylobatidae. It is one of three species of hoolock gibbon and was first described in January 2017 in the ''American Jour ...
, ''H. tianxing'' * Genus '' Hylobates'': dwarf gibbons **
Lar gibbon The lar gibbon (''Hylobates lar''), also known as the white-handed gibbon, is an endangered primate in the gibbon family, Hylobatidae. It is one of the better-known gibbons and is often kept in captivity. Taxonomy There are five subspecies of ...
or white-handed gibbon, ''H. lar'' **
Bornean white-bearded gibbon The Bornean white-bearded gibbon (''Hylobates albibarbis''), also known as the Bornean agile gibbon or southern gibbon, is a species of gibbon endemic to southern Borneo. It is an endangered species, due to the undergoing logging of the tropical ...
, ''H. albibarbis'' ** Agile gibbon or black-handed gibbon, ''H. agilis'' **
Western grey gibbon The western grey gibbon (''Hylobates abbotti''), also known as Abbot's grey gibbon, is a primate in the gibbon family, Hylobatidae. It was named after zoologist William Louis Abbott. Taxonomy Formerly, the western grey gibbon and northern grey ...
or Abbott's grey gibbon, ''H. abbotti'' **
Eastern grey gibbon The eastern grey gibbon or northern grey gibbon (''Hylobates funereus'') is a primate in the gibbon family, Hylobatidae. Taxonomy Formerly, the eastern grey gibbon and western grey gibbon (''H. abbotti'') were considered conspecific with the ...
or northern grey gibbon, ''H. funereus'' ** Müller's gibbon or southern grey gibbon, ''H. muelleri'' **
Silvery gibbon The silvery gibbon (''Hylobates moloch''), also known as the Javan gibbon, is a primate in the gibbon family Hylobatidae. It is endemic to the Indonesian island of Java, where it inhabits undisturbed rainforests up to an altitude of . It is liste ...
, ''H. moloch'' **
Pileated gibbon The pileated gibbon (''Hylobates pileatus'') is a primate in the gibbon family, Hylobatidae. The pileated gibbon has sexual dimorphism in fur coloration: males have a purely black fur, while the females have a white-grey colored fur with only th ...
or capped gibbon, ''H. pileatus'' **
Kloss's gibbon Kloss's gibbon (''Hylobates klossii''), also known as the Mentawai gibbon, the bilou or dwarf siamang, is an endangered primate in the gibbon family, Hylobatidae. It is identifiable in that it is all black, resembling the siamang with its black ...
, Mentawai gibbon or bilou, ''H. klossii'' * Genus ''
Symphalangus The siamang (, ; ''Symphalangus syndactylus'') is an arboreal, black-furred gibbon native to the forests of Indonesia, Malaysia, and Thailand. The largest of the gibbons, the siamang can be twice the size of other gibbons, reaching in height, a ...
'' **
Siamang The siamang (, ; ''Symphalangus syndactylus'') is an arboreal, black-furred gibbon native to the forests of Indonesia, Malaysia, and Thailand. The largest of the gibbons, the siamang can be twice the size of other gibbons, reaching in height, a ...
, ''S. syndactylus'' * Genus ''
Nomascus ''Nomascus'' is the second-most speciose genus of gibbons (family Hylobatidae). Originally, this genus was a subgenus of ''Hylobates'', and all individuals were considered one species, ''Hylobates concolor''. Species within ''Nomascus'' are cha ...
'': crested gibbons ** Northern buffed-cheeked gibbon, ''N. annamensis'' ** Concolor or
black crested gibbon The black crested gibbon (''Nomascus concolor'') is a Critically Endangered species of gibbon found in China, Laos, and northern Vietnam, with four subspecies. Taxonomy The taxonomy of the species is confused. Previously grouped in the gen ...
, ''N. concolor'' **
Eastern black crested gibbon The eastern black-crested gibbon (''Nomascus nasutus''), also known as the Cao-vit black crested gibbon or the Cao-vit crested gibbon, is a species of gibbon from southeast China and northern Vietnam. The term "Cao-vit" originated from the sounds ...
or Cao Vit black crested gibbon, ''N. nasutus'' **
Hainan black crested gibbon The Hainan black-crested gibbon or Hainan gibbon (''Nomascus hainanus''), is a Critically Endangered species of gibbon found only on Hainan Island, China. It was formerly considered a subspecies of the eastern black crested gibbon (''Nomascus n ...
, ''N. hainanus'' **
Northern white-cheeked gibbon The northern white-cheeked gibbon (''Nomascus leucogenys'') is a Critically Endangered species of gibbon native to South East Asia. It is closely related to the southern white-cheeked gibbon (''Nomascus siki''), with which it was previously con ...
, ''N. leucogenys'' **
Southern white-cheeked gibbon The southern white-cheeked gibbon (''Nomascus siki'') is a species of gibbon native to Vietnam and Laos. It is closely related to the northern white-cheeked gibbon (''Nomascus leucogenys'') and the yellow-cheeked gibbon (''Nomascus gabriellae'') ...
, ''N. siki'' **
Yellow-cheeked gibbon The yellow-cheeked gibbon (''Nomascus gabriellae''), also called the golden-cheeked gibbon, the yellow-cheeked crested gibbon, the golden-cheeked crested gibbon, the red-cheeked gibbon, or the buffed-cheeked gibbon, is a species of gibbon native ...
, ''N. gabriellae''


Extinct genera

* Genus ''
Bunopithecus ''Bunopithecus'' is an extinct genus of primate represented by one species, ''Bunopithecus sericus'', a gibbon or gibbon-like ape. Its remains were first discovered in Sichuan, China, in strata from the Middle Pleistocene. Although the three hoo ...
'' ** ''
Bunopithecus sericus ''Bunopithecus'' is an extinct genus of primate represented by one species, ''Bunopithecus sericus'', a gibbon or gibbon-like ape. Its remains were first discovered in Sichuan, China, in strata from the Middle Pleistocene. Although the three hoo ...
'' * Genus ''
Junzi A junzi ( or "Son of the Monarch") is a Chinese philosophical term often translated as "gentleman," "superior person",Sometimes "exemplary person". Paul R. Goldin translates it "noble man" in an attempt to capture both its early political and la ...
'' ** '' Junzi imperialis'' *Genus '' Yuanmoupithecus'' ** ''
Yuanmoupithecus xiaoyuan ''Yuanmoupithecus'' is an extinct genus of gibbons that lived 8.2 to 7.1 million years ago during the late Miocene. It is currently the oldest gibbon known. It was discovered in Yuanmou, Yunnan Province, China. The type species is ''Y. xiaoyuan'' ...
''


Hybrids

Many gibbons are hard to identify based on fur coloration, so are identified either by song or genetics. These morphological ambiguities have led to hybrids in zoos. Zoos often receive gibbons of unknown origin, so they rely on morphological variation or labels that are impossible to verify to assign species and subspecies names, so separate species of gibbons commonly are misidentified and housed together. Interspecific hybrids, within a genus, are also suspected to occur in wild gibbons where their ranges overlap. No records exist, however, of fertile hybrids between different gibbon genera, either in the wild or in captivity.


Description

One unique aspect of a gibbon's anatomy is the wrist, which functions something like a
ball-and-socket joint The ball-and-socket joint (or spheroid joint) is a type of synovial joint in which the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. The distal bone is capable of motion around an indefinite number of ...
, 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. 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. Some species such as the
siamang The siamang (, ; ''Symphalangus syndactylus'') is an arboreal, black-furred gibbon native to the forests of Indonesia, Malaysia, and Thailand. The largest of the gibbons, the siamang can be twice the size of other gibbons, reaching in height, a ...
have an enlarged
throat sac Gular skin (throat skin), in ornithology, is an area of featherless skin on birds that joins the lower mandible of the beak (or ''bill'') to the bird's neck. Other vertebrate taxa may have a comparable anatomical structure that is referred to as e ...
, which inflates and serves as a resonating chamber when the animals call. This structure can become quite large in some species, sometimes equaling the size of the animal's head. Their voices are much more powerful than that of any human singer, although they are at best half a human's height. Gibbon skulls and teeth resemble those of the great apes, and their noses are similar to those of all
catarrhine The parvorder Catarrhini , catarrhine monkeys, Old World anthropoids, or Old World monkeys, consisting of the Cercopithecoidea and apes (Hominoidea). In 1812, Geoffroy grouped those two groups together and established the name Catarrhini, "Old ...
primates. The
dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolo ...
is .Myers, P. 2000
Family Hylobatidae
Animal Diversity Web. Accessed April 05, 2011-04-05.
The siamang, which is the largest of the 18 species, is distinguished by having two fingers on each foot stuck together, hence the generic and species names ''Symphalangus'' and ''syndactylus''.


Behavior

Like all primates, 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 up to , consists of a duet between a mated pair, with their young sometimes joining in. In most species, males and some females sing solos to attract mates, as well as advertise their territories. The song can be used to identify not only which species of gibbon is singing, but also the area from which it comes. Gibbons often retain the same mate for life, although they do not always remain sexually monogamous. In addition to
extra-pair copulation Extra-pair copulation (EPC) is a mating behaviour in monogamous species. Monogamy is the practice of having only one sexual partner at any one time, forming a long-term bond and combining efforts to raise offspring together; mating outside this pai ...
s, pair-bonded gibbons occasionally "divorce". Gibbons are among nature's best brachiators. Their ball-and-socket wrist 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. They are the fastest of all tree-dwelling, nonflying mammals. Attenborough, David. ''
Life of Mammals ''The Life of Mammals'' is a nature documentary series written and presented by David Attenborough, first transmitted in the United Kingdom from 20 November 2002. A study of the evolution and habits of the various mammal species, it was the four ...
'', "Episode 8: Life in the Trees", BBC Warner, 2003.
On the ground, gibbons tend to walk bipedally, and their
Achilles tendon The Achilles tendon or heel cord, also known as the calcaneal tendon, is a tendon at the back of the lower leg, and is the thickest in the human body. It serves to attach the plantaris, gastrocnemius (calf) and soleus muscles to the calcaneus ( ...
morphology is more similar to that of humans than that of any other ape.


Diet

Gibbons' diets are about 60% fruit-based,Gibbon - Monkey Worlds
Retrieved Feb-12-2015
but they also consume twigs, leaves, insects, flowers, and occasionally birds' eggs.


Genetics

Gibbons were the first apes to diverge from the common ancestor of humans and apes about 16.8 Mya. With a
genome In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding ge ...
that has a 96% similarity to humans, the gibbon has a role as a bridge between Old World monkeys, such as macaques, and the great apes. According to a study that mapped
synteny In genetics, the term synteny refers to two related concepts: * In classical genetics, ''synteny'' describes the physical co-localization of genetic loci on the same chromosome within an individual or species. * In current biology, ''synteny'' mo ...
(genes occurring on the same chromosome) disruptions in the gibbon and human genome, humans and great apes are part of the same superfamily (
Hominoidea Apes (collectively Hominoidea ) are a clade of Old World simians native to sub-Saharan Africa and Southeast Asia (though they were more widespread in Africa, most of Asia, and as well as Europe in prehistory), which together with its sister g ...
) with gibbons. The karyotype of gibbons, however, diverged in a much more rapid fashion from the common hominoid ancestor than other apes. The common ancestor of hominoids is shown to have a minimum of 24 major
chromosomal rearrangement In genetics, a chromosomal rearrangement is a mutation that is a type of chromosome abnormality involving a change in the structure of the native chromosome. Such changes may involve several different classes of events, like deletions, duplica ...
s from the presumed gibbon ancestor's karyotype. Reaching the common gibbon ancestor's karyotype from today's various living species of gibbons will require up to 28 additional rearrangements. Adding up, this implies that at least 52 major chromosomal rearrangements are needed to compare the common hominoid ancestor to today's gibbons. No common specific sequence element in the independent rearrangements was found, while 46% of the gibbon-human synteny breakpoints occur in
segmental duplication Low copy repeats (LCRs), also known as segmental duplications (SDs), are highly homologous sequence elements within the eukaryotic genome. Repeats The repeats, or duplications, are typically 10–300 kb in length, and bear greater than 95% sequ ...
regions. This is an indication that these major differences in humans and gibbons could have had a common source of plasticity or change. Researchers view this unusually high rate of chromosomal rearrangement that is specific in small apes such as gibbons could potentially be due to factors that increase the rate of chromosomal breakage or factors that allow derivative chromosomes to be fixed in a homozygous state while mostly lost in other mammals. The whole genome of the gibbons in Southeast Asia was first sequenced in 2014 by the
German Primate Center The German Primate Centre (German: Deutsches Primatenzentrum, DPZ, founded in 1977) is a non-profit independent research and service institute located in Göttingen. It is a member of the Gottfried Wilhelm Leibniz Scientific Community and funded by ...
, including Christian Roos, Markus Brameier, and Lutz Walter, along with other international researchers. One of the gibbons that had its genome sequenced is a white-cheeked gibbon (''
Nomascus leucogenys The northern white-cheeked gibbon (''Nomascus leucogenys'') is a Critically Endangered species of gibbon native to South East Asia. It is closely related to the southern white-cheeked gibbon (''Nomascus siki''), with which it was previously con ...
'', NLE) named Asia. The team found that a jumping DNA element named LAVA
transposon A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Transpo ...
(also called gibbon-specific retrotransposon) is unique to the gibbon genome apart from humans and the great apes. The LAVA transposon increases mutation rate, thus is supposed to have contributed to the rapid and greater change in gibbons in comparison to their close relatives, which is critical for evolutionary development. The very high rate of chromosomal disorder and rearrangements (such as duplications, deletions or inversions of large stretches of DNA) due to the moving of this large DNA segment is one of the key features that are unique to the gibbon genome. A special feature of the LAVA transposon is that it positioned itself precisely between genes that are involved in
chromosome segregation Chromosome segregation is the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous chromosomes, separate from each other and migrate to opposite poles of the nucleus. This segregati ...
and distribution during cell division, which results in a premature termination state leading to an alteration in
transcription Transcription refers to the process of converting sounds (voice, music etc.) into letters or musical notes, or producing a copy of something in another medium, including: Genetics * Transcription (biology), the copying of DNA into RNA, the fir ...
. This incorporation of the jumping gene near genes involved in chromosome replication is thought to make the rearrangement in the genome even more likely, leading to a greater diversity within the gibbon genera. In addition, some characteristic genes in the gibbon genome had gone through a positive selection and are suggested to give rise to specific anatomical features for gibbons to adapt to their new environment. One of them is ''TBX5'', which is a gene that is required for the development of the front extremities or forelimbs such as long arms. The other is ''COL1A1'', which is responsible for the development of collagen, a protein that is directly involved with the forming of connective tissues, bone, and cartilage. This gene is thought to have a role in gibbons' stronger muscles. Researchers have found a coincidence between major environmental changes in Southeast Asia about 5 Mya that caused a cyclical dynamic of expansions and contractions of their forest habitat, an instance of
radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...
experienced by the gibbon genera. This may have led to the development of a suite of physical characteristics, distinct from their great ape relatives, to adapt to their habitat of dense, canopy forest. These crucial findings in genetics have contributed to the use of gibbons as a genetic model for chromosome breakage and fusion, which is a type of translocation mutation. The unusually high number of structural changes in the DNA and chromosomal rearrangements could lead to problematic consequences in some species. Gibbons, however, not only seemed to be free from problems but let the change help them effectively adapt to their environment. Thus, gibbons are organisms on which genetics research could be focused to broaden the implications to human diseases related to chromosomal changes, such as cancer, including
chronic myeloid leukemia Chronic myelogenous leukemia (CML), also known as chronic myeloid leukemia, is a cancer of the white blood cells. It is a form of leukemia characterized by the increased and unregulated growth of myeloid cells in the bone marrow and the accumulati ...
.


Conservation status

Most species are either
endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
or critically endangered (the sole exception being '' H. leuconedys'', which is vulnerable), primarily due to degradation or loss of their forest habitats.A-Z Animals: Gibbon
Retrieved Feb-12-2015
On the island of
Phuket Phuket (; th, ภูเก็ต, , ms, Bukit or ''Tongkah''; Hokkien:普吉; ) is one of the southern provinces (''changwat'') of Thailand. It consists of the island of Phuket, the country's largest island, and another 32 smaller islands of ...
in
Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...
, a volunteer-based Gibbon Rehabilitation Center rescues gibbons that were kept in captivity, and are being released back into the wild. The Kalaweit Project also has gibbon rehabilitation centers on
Borneo Borneo (; id, Kalimantan) is the third-largest island in the world and the largest in Asia. At the geographic centre of Maritime Southeast Asia, in relation to major Indonesian islands, it is located north of Java, west of Sulawesi, and eas ...
and
Sumatra Sumatra is one of the Sunda Islands of western Indonesia. It is the largest island that is fully within Indonesian territory, as well as the sixth-largest island in the world at 473,481 km2 (182,812 mi.2), not including adjacent i ...
. The IUCN Species Survival Commission Primate Specialist Group announced 2015 to be the Year of the Gibbon and initiated events to be held around the world in zoos to promote awareness of the status of gibbons.


In traditional Chinese culture

Sinologist
Robert van Gulik Robert Hans van Gulik (, 9 August 1910 – 24 September 1967) was a Dutch orientalist, diplomat, musician (of the guqin), and writer, best known for the Judge Dee historical mysteries, the protagonist of which he borrowed from the 18th-century ...
concluded gibbons were widespread in central and southern China until at least the
Song dynasty The Song dynasty (; ; 960–1279) was an imperial dynasty of China that began in 960 and lasted until 1279. The dynasty was founded by Emperor Taizu of Song following his usurpation of the throne of the Later Zhou. The Song conquered the rest ...
, and furthermore, based on an analysis of references to primates in Chinese poetry and other literature and their portrayal in Chinese paintings, the Chinese word ''yuán'' (猿) referred specifically to gibbons until they were extirpated throughout most of the country due to
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
(around the 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 forest, in contrast to the greedy macaques, attracted by human food. The
Taoist Taoism (, ) or Daoism () refers to either a school of philosophical thought (道家; ''daojia'') or to a religion (道教; ''daojiao''), both of which share ideas and concepts of Chinese origin and emphasize living in harmony with the ''Tao'' ...
s ascribed occult properties to gibbons, believing them to be able to live for several hundred years and to turn into humans. Gibbon figurines as old as from the fourth to third centuries BCE (the
Zhou dynasty The Zhou dynasty ( ; Old Chinese ( B&S): *''tiw'') was a royal dynasty of China that followed the Shang dynasty. Having lasted 789 years, the Zhou dynasty was the longest dynastic regime in Chinese history. The military control of China by th ...
) have been found in China. Later on, gibbons became a popular subject for Chinese painters, especially during the Song dynasty and early
Yuan dynasty The Yuan dynasty (), officially the Great Yuan (; xng, , , literally "Great Yuan State"), was a Mongol-led imperial dynasty of China and a successor state to the Mongol Empire after its division. It was established by Kublai, the fifth ...
, when Yì Yuánjí and Mùqī Fǎcháng excelled in painting these apes. From Chinese cultural influence, the
Zen Zen ( zh, t=禪, p=Chán; ja, text= 禅, translit=zen; ko, text=선, translit=Seon; vi, text=Thiền) is a school of Mahayana Buddhism that originated in China during the Tang dynasty, known as the Chan School (''Chánzong'' 禪宗), and ...
motif of the "gibbon grasping at the reflection of the moon in the water" became popular in Japanese art, as well, though gibbons have never occurred naturally in Japan.Geissmann, Thomas
"Gibbon paintings in China, Japan, and Korea: Historical distribution, production rate and context"
, ''Gibbon Journal'', No. 4, May 2008. (includes color reproductions of a large number of gibbon paintings by many artists)


References


External links

* *
IUCN SSC PSG Section on Small Apes

Gibbon Conservation Center

Gibbon Network and Research Lab

Gibbon Conservation Alliance

Gibbon Rehabilitation Project
* {{Authority control Primate families Miocene primates of Asia Extant Tortonian first appearances