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Gibbons are apes in the family Hylobatidae. The family historically contained one genus, but now is split into four extant genera and 20 species. Gibbons live in subtropical and tropical rainforests from eastern Bangladesh to 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 (bonobos, chimpanzees, gorillas, orangutans and humans) in being smaller, exhibiting low sexual dimorphism, and not making nests. Like all apes, gibbons are tailless. Unlike most of the great apes, gibbons frequently form long-term pair bonds. Their primary mode of locomotion, brachiation, involves swinging from branch to branch for distances up to 15 m (50 ft), at speeds as fast as 55 km/h (34 mph). They can also make leaps up to 8 m (26 ft), 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 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 monkeys). 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. An analysis based on morphology suggests that the four genera are ordered as (Symphalangus, (Nomascus, (Hoolock, Hylobates))).

Hominoidea (hominoids, apes)
Hylobatidae
(gibbons)
Symphalangus
Nomascus
Hoolock
Hylobates
Hominidae (hominids, great apes)
Ponginae
(orangutans)
Homininae
Gorillini
(gorillas)
Hominini
Panina
(chimpanzees)
Hominina (humans)

A coalescent-based species tree analysis of genome-scale datasets suggests a phylogeny for the four genera ordered as (Hylobates, (Nomascus, (Hoolock, Symphalangus))).

Hominoidea (hominoids, apes)
Hylobatidae
(gibbons)
Hylobates
Nomascus
Hoolock
Symphalangus
Hominidae (hominids, great apes)
Ponginae
(Orangutans)
Homininae
Gorillini
(Gorilla)
Hominini
Panina
(chimpanzees)
Hominina (Humans)

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 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 based on their diploid chromosome number: Hylobates (44), Hoolock (38), Nomascus (52), and Symphalangus (50). Also, three extinct genera currently are recognised: Bunopithecus, Junzi, and Yuanmoupithecus.

Family Hylobatidae: gibbons

Genus Hoolock
Western hoolock gibbon, H. hoolock
Eastern hoolock gibbon, H. leuconedys
Skywalker hoolock gibbon, H. tianxing
Genus Hylobates: dwarf gibbons
Lar gibbon or white-handed gibbon, H. lar
Bornean white-bearded gibbon, H. albibarbis
Agile gibbon or black-handed gibbon, H. agilis
Western grey gibbon or Abbott's grey gibbon, H. abbotti
Eastern grey gibbon or northern grey gibbon, H. funereus
Müller's gibbon or southern grey gibbon, H. muelleri
Silvery gibbon, H. moloch
Pileated gibbon or capped gibbon, H. pileatus
Kloss's gibbon, Mentawai gibbon or bilou, H. klossii
Genus Symphalangus
Siamang, S. syndactylus
Genus Nomascus: crested gibbons
Northern buffed-cheeked gibbon, N. annamensis
Concolor or black crested gibbon, N. concolor
Eastern black crested gibbon or Cao Vit black crested gibbon, N. nasutus
Hainan black crested gibbon, N. hainanus
Northern white-cheeked gibbon, N. leucogenys
Southern white-cheeked gibbon, N. siki
Yellow-cheeked gibbon, N. gabriellae
Extinct genera
Genus Bunopithecus
Bunopithecus sericus
Genus Junzi
Junzi imperialis
Genus Yuanmoupithecus
Yuanmoupithecus 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, 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 have an enlarged throat sac, 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 primates. The dental formula is
2.1.2.3
2.1.2.3
.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 1 km (0.62 mi), 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 copulations, 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. On the ground, gibbons tend to walk bipedally, and their Achilles tendon morphology is more similar to that of humans than that of any other ape.

Diet
Gibbons' diets are about 60% fruit-based, 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 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 (genes occurring on the same chromosome) disruptions in the gibbon and human genome, humans and great apes are part of the same superfamily (Hominoidea) 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 rearrangements 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 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.


Genus Hoolock
The whole genome of the gibbons in Southeast Asia was first sequenced in 2014 by the German Primate Center, 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, NLE) named Asia. The team found that a jumping DNA element named LAVA transposon (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 and distribution during cell division, which results in a premature termination state leading to an alteration in transcription. 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.


Siamang, Symphalangus syndactylus
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 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.

Conservation status
Most species are either endangered or critically endangered (the sole exception being H. leuconedys, which is vulnerable), primarily due to degradation or loss of their forest habitats. On the island of Phuket in Thailand, 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 and Sumatra.

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
Further information: Monkeys in Chinese culture
Sinologist Robert van Gulik concluded 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 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 (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 Taoists 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) have been found in China. Later on, gibbons became a popular subject 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, though gibbons have never occurred naturally in Japan.

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 eastern and western gorilla); Pan (the chimpanzee and the bonobo); and Homo, of which only modern humans (Homo sapiens) remain.

Numerous revisions in classifying the great apes have caused the use of the term hominid to change over time. The original meaning of "hominid" referred only to humans (Homo) and their closest extinct relatives. However, by the 1990s humans, apes, and their ancestors were considered to be "hominids".

The earlier restrictive meaning has now been largely assumed by the term hominin, which comprises all members of the human clade after the split from the chimpanzees (Pan). The current meaning of "hominid" includes all the great apes including humans. Usage still varies, however, and some scientists and laypersons still use "hominid" in the original restrictive sense; the scholarly literature generally shows the traditional usage until the turn of the 21st century.

Within the taxon Hominidae, a number of extant and extinct genera are grouped with the humans, chimpanzees, and gorillas in the subfamily Homininae; others with orangutans in the subfamily Ponginae (see classification graphic below). The most recent common ancestor of all Hominidae lived roughly 14 million years ago, when the ancestors of the orangutans speciated from the ancestral line of the other three genera. Those ancestors of the family Hominidae had already speciated from the family Hylobatidae (the gibbons), perhaps 15 to 20 million years ago.

Due to the close genetic relationship between humans and the other great apes, certain animal rights organizations, such as the Great Ape Project, argue that nonhuman great apes are persons and should be given basic human rights. Twenty-nine countries have instituted research bans to protect great apes from any kind of scientific testing.

Evolution
See also: Human evolution

Sumatran orangutan (Pongo abelii)
In the early Miocene, about 22 million years ago, there were many species of arboreally adapted primitive catarrhines from East Africa; the variety suggests a long history of prior diversification. Fossils from 20 million years ago include fragments attributed to Victoriapithecus, the earliest Old World monkey. Among the genera thought to be in the ape lineage leading up to 13 million years ago are Proconsul, Rangwapithecus, Dendropithecus, Limnopithecus, Nacholapithecus, Equatorius, Nyanzapithecus, Afropithecus, Heliopithecus, and Kenyapithecus, all from East Africa.

At sites far distant from East Africa, the presence of other generalized non-cercopithecids, that is, non-monkey primates, of middle Miocene age—Otavipithecus from cave deposits in Namibia, and Pierolapithecus and Dryopithecus from France, Spain and Austria—is further evidence of a wide diversity of ancestral ape forms across Africa and the Mediterranean basin during the relatively warm and equable climatic regimes of the early and middle Miocene. The most recent of these far-flung Miocene apes (hominoids) is Oreopithecus, from the fossil-rich coal beds in northern Italy and dated to 9 million years ago.

Molecular evidence indicates that the lineage of gibbons (family Hylobatidae), the "lesser apes", diverged from that of the great apes some 18–12 million years ago, and that of orangutans (subfamily Ponginae) diverged from the other great apes at about 12 million years. There are no fossils that clearly document the ancestry of gibbons, which may have originated in a still-unknown South East Asian hominoid population; but fossil proto-orangutans, dated to around 10 million years ago, may be represented by Sivapithecus from India and Griphopithecus from Turkey. Species close to the last common ancestor of gorillas, chimpanzees and humans may be represented by Nakalipithecus fossils found in Kenya and Ouranopithecus fossils found in Greece. Molecular evidence suggests that between 8 and 4 million years ago, first the gorillas (genus Gorilla), and then the chimpanzees (genus Pan) split off from the line leading to humans. Human DNA is approximately 98.4% identical to that of chimpanzees when comparing single nucleotide polymorphisms (see human evolutionary genetics). The fossil record, however, of gorillas and chimpanzees is limited; both poor preservation—rain forest soils tend to be acidic and dissolve bone—and sampling bias probably contribute most to this problem.

Other hominins probably adapted to the drier environments outside the African equatorial belt; and there they encountered antelope, hyenas, elephants and other forms becoming adapted to surviving in the East African savannas, particularly the regions of the Sahel and the Serengeti. The wet equatorial belt contracted after about 8 million years ago, and there is very little fossil evidence for the divergence of the hominin lineage from that of gorillas and chimpanzees—which split was thought to have occurred around that time. The earliest fossils argued by some to belong to the human lineage are Sahelanthropus tchadensis (7 Ma) and Orrorin tugenensis (6 Ma), followed by Ardipithecus (5.5–4.4 Ma), with species Ar. kadabba and Ar. ramidus.

Taxonomy
Further information: Human taxonomy
Terminology

Humans are one of the four extant hominid genera.
The classification of the great apes has been revised several times in the last few decades; these revisions have led to a varied use of the word "hominid" over time. The original meaning of the term referred to only humans and their closest relatives—what is now the modern meaning of the term "hominin". The meaning of the taxon Hominidae changed gradually, leading to a modern usage of "hominid" that includes all the great apes including humans.

A number of very similar words apply to related classifications:

A hominoid, sometimes called an ape, is a member of the superfamily Hominoidea: extant members are the gibbons (lesser apes, family Hylobatidae) and the hominids.
A hominid is a member of the family Hominidae, the great apes: orangutans, gorillas, chimpanzees and humans.
A hominine is a member of the subfamily Homininae: gorillas, chimpanzees, and humans (excludes orangutans).
A hominin is a member of the tribe Hominini: chimpanzees and humans.
A homininan, following a suggestion by Wood and Richmond (2000), would be a member of the subtribe Hominina of the tribe Hominini: that is, modern humans and their closest relatives, including Australopithecina, but excluding chimpanzees.
A human is a member of the genus Homo, of which Homo sapiens is the only extant species, and within that Homo sapiens sapiens is the only surviving subspecies.

Extant and fossil relatives of humans

Hominidae was originally the name given to the family of humans and their (extinct) close relatives, with the other great apes (that is, the orangutans, gorillas and chimpanzees) all being placed in a separate family, the Pongidae. However, that definition eventually made Pongidae paraphyletic because at least one great ape species (the chimpanzees) proved to be more closely related to humans than to other great apes. Most taxonomists today encourage monophyletic groups—this would require, in this case, the use of Pongidae to be restricted to just one closely related grouping. Thus, many biologists now assign Pongo (as the subfamily Ponginae) to the family Hominidae. The taxonomy shown here follows the monophyletic groupings according to the modern understanding of human and great ape relationships.

Humans and close relatives including the tribes Hominini and Gorillini form the subfamily Homininae (see classification graphic below). (A few researchers go so far as to refer the chimpanzees and the gorillas to the genus Homo along with humans.) But, those fossil relatives more closely related to humans than the chimpanzees represent the especially close members of the human family, and without necessarily assigning subfamily or tribal categories.

Many extinct hominids have been studied to help understand the relationship between modern humans and the other extant hominids. Some of the extinct members of this family include Gigantopithecus, Orrorin, Ardipithecus, Kenyanthropus, and the australopithecines Australopithecus and Paranthropus.

The exact criteria for membership in the tribe Hominini under the current understanding of human origins are not clear, but the taxon generally includes those species that share more than 97% of their DNA with the modern human genome, and exhibit a capacity for language or for simple cultures beyond their 'local family' or band. The theory of mind concept—including such faculties as empathy, attribution of mental state, and even empathetic deception—is a controversial criterion; it distinguishes the adult human alone among the hominids. Humans acquire this capacity after about four years of age, whereas it has not been proven (nor has it been disproven) that gorillas or chimpanzees ever develop a theory of mind. This is also the case for some New World monkeys outside the family of great apes, as, for example, the capuchin monkeys.

However, even without the ability to test whether early members of the Hominini (such as Homo erectus, Homo neanderthalensis, or even the australopithecines) had a theory of mind, it is difficult to ignore similarities seen in their living cousins. Orangutans have shown the development of culture comparable to that of chimpanzees, and some say the orangutan may also satisfy those criteria for the theory of mind concept. These scientific debates take on political significance for advocates of great ape personhood.

See also: List of hominoids
There are eight living species of great ape which are classified in four genera. The following classification is commonly accepted:

Family Hominidae: humans and other great apes; extinct genera and species excluded
Subfamily Ponginae
Tribe Pongini
Genus Pongo
Bornean orangutan, Pongo pygmaeus
Pongo pygmaeus pygmaeus
Pongo pygmaeus morio
Pongo pygmaeus wurmbii
Sumatran orangutan, Pongo abelii
Tapanuli orangutan, Pongo tapanuliensis
Subfamily Homininae
Tribe Gorillini
Genus Gorilla
Western gorilla, Gorilla gorilla
Western lowland gorilla, Gorilla gorilla gorilla
Cross River gorilla, Gorilla gorilla diehli
Eastern gorilla, Gorilla beringei
Mountain gorilla, Gorilla beringei beringei
Eastern lowland gorilla, Gorilla beringei graueri
Tribe Hominini
Subtribe Panina
Genus Pan
Chimpanzee, Pan troglodytes
Central chimpanzee, Pan troglodytes troglodytes
Western chimpanzee, Pan troglodytes verus
Nigeria-Cameroon chimpanzee, Pan troglodytes ellioti
Eastern chimpanzee, Pan troglodytes schweinfurthii
Bonobo, Pan paniscus
Subtribe Hominina
Genus Homo
Human, Homo sapiens
Anatomically modern human, Homo sapiens sapiens
Fossil

In addition to the extant species and subspecies, archaeologists, paleontologists, and anthropologists have discovered and classified numerous extinct great ape species as below, based on the taxonomy shown.

Tribe Lufengpithecini †
Lufengpithecus
Lufengpithecus lufengensis
Lufengpithecus keiyuanensis
Lufengpithecus hudienensis
Meganthropus
Meganthropus palaeojavanicus
Tribe Sivapithecini†
Ankarapithecus
Ankarapithecus meteai
Sivapithecus
Sivapithecus brevirostris
Sivapithecus punjabicus
Sivapithecus parvada
Sivapithecus sivalensis
Sivapithecus indicus
Gigantopithecus
Gigantopithecus bilaspurensis
Gigantopithecus blacki
Gigantopithecus giganteus
Tribe Pongini
Khoratpithecus†
Khoratpithecus ayeyarwadyensis
Khoratpithecus piriyai
Khoratpithecus chiangmuanensis
Pongo (orangutans)
Pongo hooijeri†
Subfamily Homininae
Tribe Dryopithecini †
Kenyapithecus
Kenyapithecus wickeri
Danuvius
Danuvius guggenmosi
Pierolapithecus
Pierolapithecus catalaunicus
Udabnopithecus
Udabnopithecus garedziensis
Ouranopithecus
Ouranopithecus macedoniensis
Otavipithecus
Otavipithecus namibiensis
Morotopithecus (placement disputed)
Morotopithecus bishopi
Oreopithecus (placement disputed)
Oreopithecus bambolii
Nakalipithecus
Nakalipithecus nakayamai
Anoiapithecus
Anoiapithecus brevirostris
Hispanopithecus
Hispanopithecus laietanus
Hispanopithecus crusafonti
Dryopithecus
Dryopithecus wuduensis
Dryopithecus fontani
Dryopithecus brancoi
Dryopithecus laietanus
Dryopithecus crusafonti
Rudapithecus
Rudapithecus hungaricus
Samburupithecus
Samburupithecus kiptalami
Tribe Gorillini
Chororapithecus † (placement debated)
Chororapithecus abyssinicus
Tribe Hominini
Subtribe Panina
Subtribe Hominina
Graecopithecus †
Graecopithecus freybergi
Sahelanthropus†
Sahelanthropus tchadensis
Orrorin†
Orrorin tugenensis
Ardipithecus†
Ardipithecus ramidus
Ardipithecus kadabba
Kenyanthropus†
Kenyanthropus platyops
Praeanthropus†
Praeanthropus bahrelghazali
Praeanthropus anamensis
Praeanthropus afarensis
Australopithecus†
Australopithecus africanus
Australopithecus garhi
Australopithecus sediba
Australopithecus deyiremeda
Paranthropus†
Paranthropus aethiopicus
Paranthropus robustus
Paranthropus boisei
Homo – close relatives of modern humans
Homo gautengensis† (also classified as H. habilis)
Homo rudolfensis† (membership in Homo uncertain)
Homo habilis† (membership in Homo uncertain)
Homo naledi†
Dmanisi Man, Homo georgicus† (thought by some to be an early subspecies of Homo erectus)
Homo ergaster† (considered by some to be an early subspecies of Homo erectus)
Homo erectus†
Homo erectus bilzingslebenensis †
Java Man, Homo erectus erectus †
Lantian Man, Homo erectus lantianensis †
Nanjing Man, Homo erectus nankinensis †
Peking Man, Homo erectus pekinensis †
Solo Man, Homo erectus soloensis †
Tautavel Man, Homo erectus tautavelensis †
Yuanmou Man, Homo erectus yuanmouensis †
Flores Man or Hobbit, Homo floresiensis†
Homo luzonensis †
Homo antecessor† (thought by some to be a late H. erectus or early H. heidelbergensis)
Homo heidelbergensis† (also classified as H. sapiens heidelbergensis)
Homo cepranensis† (also classified as H. heidelbergensis)
Homo helmei† (also classified as late H. heidelbergensis or early H. sapiens)
Homo tsaichangensis† (thought by some to be a subspecies of H. erectus or a Denisovan)
Denisovans (scientific name not yet assigned)†
Neanderthal, Homo neanderthalensis† (sometimes called Homo sapiens neanderthalensis)
Homo rhodesiensis† (thought by some to be an African subspecies of H. heidelbergensis or an early H. sapiens)
Modern human, Homo sapiens (sometimes called Homo sapiens sapiens)
Homo sapiens idaltu†
Archaic Homo sapiens†
Description

The great apes are tailless primates, with the smallest living species being the bonobo at 30 to 40 kilograms (66 to 88 lb) in weight, and the largest being the eastern gorillas, with males weighing 140 to 180 kilograms (310 to 400 lb). In all great apes, the males are, on average, larger and stronger than the females, although the degree of sexual dimorphism varies greatly among species. Hominid teeth are similar to those of the Old World monkeys and gibbons, although they are especially large in gorillas. The dental formula is
2.1.2.3
2.1.2.3
. Human teeth and jaws are markedly smaller for their size than those of other apes, which may be an adaptation to not only having supplanted with extensive tool use the role of jaws in hunting and fighting, but also eating cooked food since the end of the Pleistocene.

Behavior
Although most living species are predominantly quadrupedal, they are all able to use their hands for gathering food or nesting materials, and, in some cases, for tool use. They build complex sleeping platforms, also called nests, in trees to sleep in at night, but chimpanzees and gorillas also build terrestrial nests, and gorillas can also sleep on the bare ground.

All species are omnivorous, although chimpanzees and orangutans primarily eat fruit. When gorillas run short of fruit at certain times of the year or in certain regions, they resort to eating shoots and leaves, often of bamboo, a type of grass. Gorillas have extreme adaptations for chewing and digesting such low-quality forage, but they still prefer fruit when it is available, often going miles out of their way to find especially preferred fruits. Humans, since the Neolithic revolution, have consumed mostly cereals and other starchy foods, including increasingly highly processed foods, as well as many other domesticated plants (including fruits) and meat.

Gestation in great apes lasts 8–9 months, and results in the birth of a single offspring, or, rarely, twins. The young are born helpless, and require care for long periods of time. Compared with most other mammals, great apes have a remarkably long adolescence, not being weaned for several years, and not becoming fully mature for eight to thirteen years in most species (longer in orangutans and humans). As a result, females typically give birth only once every few years. There is no distinct breeding season.

Gorillas and chimpanzees live in family groups of around five to ten individuals, although much larger groups are sometimes noted. Chimpanzees live in larger groups that break up into smaller groups when fruit becomes less available. When small groups of female chimpanzees go off in separate directions to forage for fruit, the dominant males can no longer control them and the females often mate with other subordinate males. In contrast, groups of gorillas stay together regardless of the availability of fruit. When fruit is hard to find, they resort to eating leaves and shoots.

This fact is related to gorillas' greater sexual dimorphism relative to that of chimpanzees; that is, the difference in size between male and female gorillas is much greater than that between male and female chimpanzees. This enables gorilla males to physically dominate female gorillas more easily. In both chimpanzees and gorillas, the groups include at least one dominant male, and young males leave the group at maturity.

Legal status
Main articles: Great ape personhood, Great Ape Project, and Countries banning non-human ape experimentation
Due to the close genetic relationship between humans and the other great apes, certain animal rights organizations, such as the Great Ape Project, argue that nonhuman great apes are persons and, per the Declaration on Great Apes, should be given basic human rights. In 1999, New Zealand was the first country to ban any great ape experimentation, and now 29 countries have currently instituted a research ban to protect great apes from any kind of scientific testing.

On 25 June 2008, the Spanish parliament supported a new law that would make "keeping apes for circuses, television commercials or filming" illegal. On 8 September 2010, the European Union banned the testing of great apes.

Gibbons are apes in the family Hylobatidae. The family historically contained one genus, but now is split into four extant genera and 20 species. Gibbons live in subtropical and tropical rainforests from eastern Bangladesh to 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 (bonobos, chimpanzees, gorillas, orangutans and humans) in being smaller, exhibiting low sexual dimorphism, and not making nests. Like all apes, gibbons are tailless. Unlike most of the great apes, gibbons frequently form long-term pair bonds. Their primary mode of locomotion, brachiation, involves swinging from branch to branch for distances up to 15 m (50 ft), at speeds as fast as 55 km/h (34 mph). They can also make leaps up to 8 m (26 ft), 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 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 monkeys). 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. An analysis based on morphology suggests that the four genera are ordered as (Symphalangus, (Nomascus, (Hoolock, Hylobates))).

Hominoidea (hominoids, apes)
Hylobatidae
(gibbons)
Symphalangus
Nomascus
Hoolock
Hylobates
Hominidae (hominids, great apes)
Ponginae
(orangutans)
Homininae
Gorillini
(gorillas)
Hominini
Panina
(chimpanzees)
Hominina (humans)

A coalescent-based species tree analysis of genome-scale datasets suggests a phylogeny for the four genera ordered as (Hylobates, (Nomascus, (Hoolock, Symphalangus))).

Hominoidea (hominoids, apes)
Hylobatidae
(gibbons)
Hylobates
Nomascus
Hoolock
Symphalangus
Hominidae (hominids, great apes)
Ponginae
(Orangutans)
Homininae
Gorillini
(Gorilla)
Hominini
Panina
(chimpanzees)
Hominina (Humans)

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 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 based on their diploid chromosome number: Hylobates (44), Hoolock (38), Nomascus (52), and Symphalangus (50). Also, three extinct genera currently are recognised: Bunopithecus, Junzi, and Yuanmoupithecus.

Family Hylobatidae: gibbons

Genus Hoolock
Western hoolock gibbon, H. hoolock
Eastern hoolock gibbon, H. leuconedys
Skywalker hoolock gibbon, H. tianxing
Genus Hylobates: dwarf gibbons
Lar gibbon or white-handed gibbon, H. lar
Bornean white-bearded gibbon, H. albibarbis
Agile gibbon or black-handed gibbon, H. agilis
Western grey gibbon or Abbott's grey gibbon, H. abbotti
Eastern grey gibbon or northern grey gibbon, H. funereus
Müller's gibbon or southern grey gibbon, H. muelleri
Silvery gibbon, H. moloch
Pileated gibbon or capped gibbon, H. pileatus
Kloss's gibbon, Mentawai gibbon or bilou, H. klossii
Genus Symphalangus
Siamang, S. syndactylus
Genus Nomascus: crested gibbons
Northern buffed-cheeked gibbon, N. annamensis
Concolor or black crested gibbon, N. concolor
Eastern black crested gibbon or Cao Vit black crested gibbon, N. nasutus
Hainan black crested gibbon, N. hainanus
Northern white-cheeked gibbon, N. leucogenys
Southern white-cheeked gibbon, N. siki
Yellow-cheeked gibbon, N. gabriellae
Extinct genera
Genus Bunopithecus
Bunopithecus sericus
Genus Junzi
Junzi imperialis
Genus Yuanmoupithecus
Yuanmoupithecus 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, 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 have an enlarged throat sac, 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 primates. The dental formula is
2.1.2.3
2.1.2.3
.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 1 km (0.62 mi), 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 copulations, 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. On the ground, gibbons tend to walk bipedally, and their Achilles tendon morphology is more similar to that of humans than that of any other ape.

Diet
Gibbons' diets are about 60% fruit-based, 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 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 (genes occurring on the same chromosome) disruptions in the gibbon and human genome, humans and great apes are part of the same superfamily (Hominoidea) 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 rearrangements 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 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.


Genus Hoolock
The whole genome of the gibbons in Southeast Asia was first sequenced in 2014 by the German Primate Center, 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, NLE) named Asia. The team found that a jumping DNA element named LAVA transposon (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 and distribution during cell division, which results in a premature termination state leading to an alteration in transcription. 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.


Siamang, Symphalangus syndactylus
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 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.

Conservation status
Most species are either endangered or critically endangered (the sole exception being H. leuconedys, which is vulnerable), primarily due to degradation or loss of their forest habitats. On the island of Phuket in Thailand, 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 and Sumatra.

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
Further information: Monkeys in Chinese culture
Sinologist Robert van Gulik concluded 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 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 (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 Taoists 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) have been found in China. Later on, gibbons became a popular subject 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, though gibbons have never occurred naturally in Japan.

A short lifeguard tower stands amid a quiet scene at Vencie Beach, CA.

A waning gibbous moon hangs low, next to a Mexican fan palm (Washingtonia robusta) on a quiet, warm and muggy morning at Venice Beach, CA. Homeless people can be found sleeping throughout this stretch of coast.

California poppies (Eschscholzia californica) burst through a chain-link fence at Memorial South Park, softening the geometric barrier with splashes of golden beauty. Thereby making a more lovely experience for passers-by.

Sunny, 18ºC, a light breeze: Pleasant April weather from the vantage of Jericho Beach.

Wow, this photo explored on 06 Jun 2014, a nice surprise! 14,156 views as of 21:56 PDT 06 Jun 2014 (~36 hr).

Thanks to all who took the time to see this image!

A massive Sikorsky CH-124 Sea King slowly descends on Deadman Island, with door open, just to the south of Stanley Park. The small 3.8 ha island is home of a Canadian Forces Naval Reserve, a controversial arrangement due to the island being a First Nations burial site.

Instead of the nearly obligatory photo of the Old Faithful eruption in progress--there are perhaps a hundred million photos of this--I instead capture the wait in anticipation of the big event. Here tourists begin to gather, with Old Faithful steaming in the distance. The wait proved long. The geyser did not blast away until well after the expected timeframe. Some curious Ravens and busy squirrels provided the pre-show entertainment.

The main question being explored here is: What is the trade-off between bokeh (e.g. subject isolation) and focal length, given similar framing of a subject. Or, in other words, when framing a subject in a similar manner, is the bokeh always the same at a given aperture regardless of focal length (obviously not). If not, then what provides the strongest gains in subject isolation, greater focal length or wider aperture?

This test has not been rigorously operated, but is fairly well controlled and set up in a real-world environment with a common subject (human). The subject, in this case my daughter, is in the exact same location with each shot. I did all the moving, attempting to reframe the subject exactly as before, but with a different focal length. I started at 24mm and roughly doubled the focal length to 200mm with each step, then followed with a 300mm perspective. I used a Canon EOS 60D, tripod and remote shutter release to capture each frame. Full-format cameras would produce somewhat different results, but the general conclusions drawn from this examination still hold. Also, different lenses would also likely produce somewhat different results, but probably not enough to affect the general conclusions. Do not read too much into the indicated focus distances as they are rough approximations--it is about time that these seemingly fancy digital cameras returned focus distance estimates with high precision and accuracy either in the viewfinder or on one of the screens.

Best viewed large. These composites are large files, about 19 MB, and it may require some time to download the full-resolution versions.

In Test 2, the set of photos explores a closer crop of the subject. By being nearer to the subject, there is a stronger bokeh effect, aiding interpretation. For each focal length, images were captured at two different apertures: f/4 to the left and f/8 to the right. As seen with Test 1, some Ents sneak up from behind as the focal length, and associated foreshortening, increases.

With this framing, I would say (keep in mind the subjectivity of this kind of examination) that significant isolation of the figure begins around 50mm with an aperture of f/4 and at f/8 around 100mm. With a focal length of 300mm, f/8 appears to be approximately similar to 100mm at f/4. Finer gradations of focal length, say 25mm steps, and aperture, say 1-stop increments over a wider range, would provide more precise results. However, roughly speaking, it appears that a doubling of the focal length provides about 2 full stops worth of subject isolation.

What does this tell us about the significance of f/2.8 verses f/4 when it comes to a useful level subject isolation (again reflecting on the subjective nature of what necessitates a pleasing background blur)?

The main question being explored here is: What is the trade-off between bokeh (e.g. subject isolation) and focal length, given similar framing of a subject. Or, in other words, when framing a subject in a similar manner, is the bokeh always the same at a given aperture regardless of focal length (obviously not). If not, then what provides the strongest gains in subject isolation, greater focal length or wider aperture?

This test has not been rigorously operated, but is fairly well controlled and set up in a real-world environment with a common subject (human). The subject, in this case my daughter, is in the exact same location with each shot. I did all the moving, attempting to reframe the subject exactly as before, but with a different focal length. I started at 24mm and roughly doubled the focal length to 200mm with each step, then followed with a 300mm perspective. I used a Canon EOS 60D, tripod and remote shutter release to capture each frame. Full-format cameras would produce somewhat different results, but the general conclusions drawn from this examination still hold. Also, different lenses would also likely produce somewhat different results, but probably not enough to affect the general conclusions. Do not read too much into the indicated focus distances as they are rough approximations--it is about time that these seemingly fancy digital cameras returned focus distance estimates with high precision and accuracy either in the viewfinder or on one of the screens.

Best viewed large. These composites are large files, about 19 MB, and it may require some time to download the full-resolution versions.

In this particular group of shots, I went for full-figure framing and only captured images at f/4. Next to each frame is a 50% crop of the image, to help show the background blurring more clearly. As the focal length increases, the trees in the distant background appear to gradually creep up on the figure. Through the use of telephoto lenses, the Ent can be created with ease! Keep in mind that the person remains the same distance from the trees with each shot. The five frames clearly demonstrate the extreme foreshortening that can be achieved at longer focal lengths.

What is also apparent is that at the same aperture, the amount of background blurring increases when the subject is framed similarly with each shot. Given that an easy way to create creamy bokeh is to move closer to the subject, and act that narrows the depth-of-field, and that the camera had to be moved further from the subject with each increase in focal length in the study, this is a clear demonstration that the focal planes of long lenses tend to be dramatically narrower than those of wide-angle lenses.

Among this group of shots, I would say that subject isolation is starting to get significant at 100mm, with more amplified results at 200mm and beyond. When strong subject isolation is desired, this series of images suggest that a good choice is to go with maximum focal length. This has the effect of requiring one to take photos further from the subject to achieve framing similar to what could be achieved at shorter focal lengths, and this may not always be possible given the constraints of the desired setting.

My daughter poses next to some impressive stacks of snow. She enjoyed the seemingly boundless snowfall. She could grow up, graduate university and be well into her career before another such snowstorm happens. Of course, the weather is capricious, and sometimes rare events cluster temporally.

The photographer, by the way, is in danger from the white missile that she carries. Snowball wars, and snow forts, spring up throughout the city during the long snow of 2008.

The first snowstorm began on the evening of 13 Dec 2008. After which, one snow event after another followed into the New Year. For a location where icy accumulations usually only lasts a few days at most, the incessant series of snowstorms, a number of which dropped 15 cm (~6") or more of the white stuff in a single fall, caught many Vancouverites by surprise. It had been decades since snow had persisted so long. And one had to look back to 1996 to find an event--a single one in the case of the "Blizzard of '96"--that produced a similar thickness of accumulation. Due in part to the prolonged onslaught right in the heart of all the grim news about the Great Recession, some people began calling the prolonged winter weather the "snowpocalypse." Others called it "snowmageddon."

The five photos I posted today are from Christmas Eve. By this time, the snow depth approached, but had not reached, peak values for the entire month-long winter weather outbreak. On this day, the fourth snowstorm in the series dropped 22.2 cm (8.7") of snow at Tisdall Park in my neighbourhood. Total snow depth, new snow piled upon old, had reached 46.4 cm (18.3"). Needless to say, with light snow showers the next morning, Vancouver had a seriously white Christmas, a rare treat for the normally moderate coastal location.

A crow (Corvus brachyrhynchos) scans the lawn for food even as two nearby pooches watch intently.

This dancer perfected springing from the ground. He made these high bounces seem effortless. Quite fun to watch.

Photo taken during a recent Dusk Dances performance at Queen Elizabeth Park in Vancouver, BC.

Three people, seemingly at bliss initially, soon battle over a small couch during a recent Dusk Dances performance at Queen Elizabeth Park in Vancouver, BC.

Three women bristle over their would-be lovers during a recent Dusk Dances performance at Queen Elizabeth Park in Vancouver, BC.

With a loud "Who's your leader?" a lively woman guides the audience between dances during a recent series of Dusk Dances performances at Queen Elizabeth Park in Vancouver, BC.

Three women recoil in fear at the prospect of not finding a lover during a recent Dusk Dances performance at Queen Elizabeth Park in Vancouver, BC.

Three women swing their parasols high during a recent Dusk Dances performance at Queen Elizabeth Park in Vancouver, BC.

Looking south, down Cambie, to the low, flat expanse of the Fraser River Delta. The Canada Line, an electric light-rail train system, follows Cambie Street, stretching from downtown Vancouver to Richmond and also the Vancouver International Airport. At this location, the automated train is a subway, hidden underneath the crush of traffic on the surface roads. There appears to be a fondness for cherry trees and blossoms in Vancouver (seen at the right). Spring can be a magnificent season of color: Entire streets lined with cherry trees often appear to be draped in clouds of soft pink bloom.