Primates n : an animal order including lemurs and tarsiers and monkeys and apes and human beings [syn: order Primates]

see Primates

English

Noun

primates

1. Plural of primate

A primate is any member of the biological order Primates, the group that contains all the species commonly related to the lemurs, monkeys, and apes, with the last category including humans. Primates are found all over the world. Non-human primates occur mostly in Central and South America, Africa, and South Asia. A few species exist as far north in the Americas as southern Mexico, and as far north in Asia as northern Japan.

The order Primates was established by Carl Linnaeus in 1758, in the tenth edition of his book Systema Naturae, for the genera Homo (humans), Simia (other apes and monkeys), Lemur (prosimians) and Vespertilio (bats). In the first edition of the same book (1735), he had used the name Anthropomorpha for Homo, Simia and Bradypus (sloths). In 1839, Henri-Marie Ducrotay de Blainville, following Linnaeus and imitating his nomenclature, established the orders Secundates (including the suborders Chiroptera, Insectivora and Carnivora), Tertiates (or Glires) and Quaternates (including Gravigrada, Pachydermata and Ruminantia), but these new taxa were not accepted.

The Latin primas means "one of the first, excellent, noble" (nominative plural primates). The English singular primate was derived via back-formation from the Latin inflected form.

The Primates order is divided informally into three main groupings: prosimians, monkeys of the New World, and monkeys and apes of the Old World. The prosimians are species whose bodies most closely resemble that of the early proto-primates. The most well known of the prosimians, the lemurs, are located on the island of Madagascar and to a lesser extent on the Comoros Islands, isolated from the rest of the world. The New World monkeys include the familiar capuchin, howler, and squirrel monkeys. They live exclusively in the Americas. Discounting humans, the rest of the simians, the Old World monkeys and the apes, inhabit Africa and southern and central Asia, although fossil evidence shows many species existed in Europe as well.

According to fossil evidence, primitive ancestors of primates already existed in the late Cretaceous. Molecular clock studies suggest that the primate branch is even more ancient (originating at least in the mid-Cretaceous). They are now thought to be most closely related to flying lemurs and, more distantly, to treeshrews. They probably have descended from Plesiadapiformes.

Description and behaviour

General description

Primates have radiated in arboreal habitats and therefore retain many characteristics are adaptations to this environment. They can be either herbivorous or omnivorous. They have a primitive (unspecialized) body plan, 2 mammary glands, 1-2 young per pregnancy and a long gestation and developmental period. Primates are frequently highly social, with flexible dominance hierarchies. New World species form monogamous pair bonds, and show substantial paternal care of young unlike most Old World monkeys.

Skull

Eyes

Primates have forward-facing colour binocular vision which was useful for the brachiating ancestors of humans, particularly for finding and collecting food, although recent studies suggest it was more useful in courtship. Strepsirrhines have a postorbital bar, a bone which runs around the eyesocket, to protect their eyes, which is in contrast to the higher primates, haplorrhines, which have evolved fully enclosed sockets.

Hands and feet

All primates have five digits on each limb (pentadactyly), with keratin nails on the anterior ends. The ventral sides of the hands and feet have tactile pads on the distal phalanges. They have opposable thumbs, which are a characteristic primate feature, but are not limited to this order; opossums, for example, also have opposing thumbs. These thumbs allow some species to use tools to perform some tasks. In primates, the combination of opposing thumbs, short fingernails (rather than claws) and long, inward-closing fingers is a relic of the ancestral practice of gripping branches, and has, in part, allowed some species to develop brachiation as a significant means of transportation. Prosimians have clawlike nails on the second toes of their feet.

Limbs and vertebral column

The primate clavicle is retained as prominent element of the pectoral girdle, this allows the shoulder joint broad mobility. Apes have more mobile shoulder joints and arms due to the dorsal position of the scapula, broad ribcages that are flatter front-to-back, and a shorter, less mobile spine compared to Old World monkeys (with caudal vertebrae greatly reduced, resulting in tail loss in some species).

Prehensile tail

Old World monkeys are unlike apes in that most have tails, and unlike the New World monkeys in that their tails are never prehensile. Only the New World Atelidae family have prehensile tails.

Mouth and teeth

Primates have a shortened rostrum (snout).

Nose

Technically, the distinction of Old World monkeys from New World monkeys depends on the structure of the nose, and the distinction of Old World monkeys from apes depends on dentition. In New World monkeys the nostrils face sideways, whilst in Old World monkeys, they face downwards.

Sexual dimorphism

Simians show some degree of sexual dimorphism. Old World species (apes and some monkeys) often exhibit sexual dimorphism, which can also be found to a lesser degree in some New World species. Recent studies have mainly used the technique of comparative analysis to examine both the variation in the expression of the dimorphism among primates and the fundamental causes of sexual dimorphism. Primates usually have dimorphism in body mass and canine tooth size along with pelage and skin colour. The dimorphism in primates has been attributed to many factors:

• Mating system - Polygynous species are more sexually dimorphic than monogamous species, such as the New World monkeys. It is also associated with greater male gonadal investment than what is found in closely related monogamous species.
• Size - Larger species are more sexually dimorphic than smaller species. These studies have shown that dimorphism is the product of changes in both male and female traits. Ontogenic scaling, where relative extension of a common growth trajectory occurs, may show some insight into the relationship between sexual dimorphism and growth patterns. There is some evidence from the fossil record that suggests that there was convergent evolution of dimorphism, and some extinct hominids probably exceeded dimorphism of any living primate.

Color vision

Color vision in primates is unique in the evolution of most eutherian mammals. While our remote vertebrate ancestors possessed trichromacy, our nocturnal, warm-blooded, mammalian ancestors lost one of three cones in the retina at the time of dinosaurs. Fish, reptiles and birds are therefore trichromatic while all mammals, with the exception of some primates and marsupials, are strictly dichromats.

Primates achieve trichromacy through color receptors (cone cells), with spectral peaks in the violet (short wave, S), green (middle wave, M), and yellow-green (long wave, L) wavelengths. All primates, however, are not capable of trichromacy. The catarrhines are routinely trichromatic, meaning that both males and females possess three opsins (pigments) sensitive to 430 nm, 530 nm, and 560 nm wavelengths. Platyrrhines, on the other hand are non-routinely trichromatic; only a small population of platyrrhines are trichromats.

Howler monkeys have reinvented routine trichromatism through a recent gene duplication of the red-green opsin gene. This has allowed trichromacy for both sexes, the X chromosome has gained two loci to house both the green allele and the red allele. Howler monkeys are perhaps the most folivorous of the New World monkeys. Fruits are not part of their diet, and the type of leaves they consume (young, nutritive, and digestible), are detectable only by a red-green signal. Field work exploring the dietary preferences of howler monkeys suggest that routine trichromacy was environmentally selected for.

Locomotion

Various species of primates move by brachiation, bipedalism, leaping, arboreal and terrestrial quadrupedalism, climbing or knuckle walking.

Most prosimians are arboreal quadrupedalists and climbers. Many are also terrestrial quadrupedalists, while some are leapers. Most monkeys are both arboreal and terrestrial quadrupedalists and climbers. Gibbons are brachiators. Chimps, orangutans, and gorillas all knuckle walk, and can move bipedally for short distances. Humans are the only fully bipedal species.

Laughter

Laughter may not be confined or unique to humans, despite Aristotle's observation that "only the human animal laughs". But some behavioural psychologists argue that self-awareness of one's situation, or the ability to identify with somebody else's predicament, are prerequisites for laughter, so animals do not laugh like humans do.

Chimpanzees, gorillas, and orangutans show laughter-like vocalizations in response to physical contact, such as wrestling, play chasing, or tickling. This is documented in wild and captive chimpanzees. Chimpanzee laughter is not readily recognizable to humans as such, because it is generated by alternating inhalations and exhalations that sound more like breathing and panting. The differences between chimpanzee and human laughter may be the result of adaptations that have evolved to enable human speech. There are instances in which non-human primates have been reported to have expressed joy. One study analyzed and recorded sounds made by human babies and Bonobos (a species of chimpanzee) when they were tickled. It found although the Bonobo's laugh was a higher frequency, the laugh followed the same spectrographic pattern of human babies to include as similar facial expressions. Humans and chimpanzees share similar ticklish areas of the body such as the armpits and belly. The enjoyment of tickling in chimpanzees does not diminish with age.

Habitat

Primates evolved from arboreal animals and many modern species live mostly in trees and hardly ever come to the ground. Other species are partially terrestrial, such as baboons and the Patas Monkey. Only a few species are fully terrestrial, such as the Gelada and Humans. Primates live in a diverse number of forested habitats, including rain forests, mangrove forests, and mountain forests to altitudes of over 3000 m. Although most species are generally shy of water, a few are fine swimmers and are comfortable in swamps and watery areas, including the Proboscis Monkey, De Brazza's Monkey and Allen's Swamp Monkey, which even developed small webbing between its fingers. Some primates, such as the Rhesus Macaque and the Hanuman Langur, can exploit human-modified environments and even live in cities.

Phylogeny

In older classifications, the Primates were divided into two superfamilies: Prosimii and Anthropoidea. The Prosimii included all of the prosimians: all of Strepsirrhini plus the tarsiers. The Anthropoidea contained all of the simians.

In modern, cladistic reckonings, the Primate order is also a true clade. The suborder Strepsirrhini, the "wet-nosed" primates, split off from the primitive primate line about 63 million years ago (mya). The seven strepsirhine families are the four related lemur families and the three remaining families that include the lorises, the Aye-aye, the galagos, and the pottos. The recently published third edition of Mammal Species of the World (MSW3) lists 376 species. .

Classification

• ORDER PRIMATES
  • Suborder Strepsirrhini: non-tarsier prosimians
    • Infraorder Lemuriformes
      • Superfamily Cheirogaleoidea
        • Family Cheirogaleidae: dwarf lemurs and mouse-lemurs (30 species)
      • Superfamily Lemuroidea
        • Family Lemuridae: lemurs (19 species)
        • Family Lepilemuridae: sportive lemurs (22 species)
        • Family Indriidae: woolly lemurs and allies (14 species)
    • Infraorder Chiromyiformes
      • Family Daubentoniidae: Aye-aye (1 species)
    • Infraorder Lorisiformes
      • Family Lorisidae: lorises, pottos and allies (9 species)
      • Family Galagidae: galagos (19 species)
  • Suborder Haplorrhini: tarsiers, monkeys and apes
    • Infraorder Tarsiiformes
      • Family Tarsiidae: tarsiers (8 species)
    • Infraorder Simiiformes
      • Parvorder Platyrrhini: New World monkeys
        • Family Cebidae: marmosets, tamarins, capuchins and squirrel monkeys (56 species)
        • Family Aotidae: night or owl monkeys (douroucoulis) (7 species)
        • Family Pitheciidae: titis, sakis and uakaris (41 species)
        • Family Atelidae: howler, spider and woolly monkeys (24 species)
      • Parvorder Catarrhini
        • Superfamily Cercopithecoidea
          • Family Cercopithecidae: Old World monkeys (135 species)
        • Superfamily Hominoidea
          • Family Hylobatidae: gibbons or "lesser apes" (13 species)
          • Family Hominidae: humans and other great apes (7 species)

Some prehistoric primates

• Adapis, an adapid
• Aegyptopithecus zeuxis, an early haplorrhine
• Australopithecus, ape-like human ancestor
• Branisella boliviana, an early New World monkey
• Dryopithecus, an early ape
• Eosimias, an early catarrhine
• Gigantopithecus, the largest ape
• Godinotia, an adapid
• Megaladapis, a giant lemur
• Notharctus, an adapid
• Pierolapithecus catalaunicus, a possible ancestor of large apes
• Plesiopithecus teras, a relative of lorises and galagos
• Pliopithecus, ancestor of the modern gibbons
• Protopithecus brasiliensis, a giant New World monkey
• Sahelanthropus tchadensis, a possible ancestor of humans
• Sivapithecus, an early ape
• Teilhardina, the earliest haplorrhines
• Victoriapithecus, an early Old World monkey

Primate hybrids

In The Variation Of Animals And Plants Under Domestication Charles Darwin noted: "Several members of the family of Lemurs have produced hybrids in the Zoological Gardens."

Many gibbons are hard to identify based on fur coloration and are identified either by song or genetics. These morphological ambiguities have led to hybrids in zoos. Zoo gibbons usually come from the black market pet trade in Southeast Asia, which transported gibbons across countries all over the region. As a result, perhaps as much as 95% of zoo gibbons are of unknown geographic origin. As most zoos rely on morphological variation or labels that are impossible to verify to assign species and subspecies names, it is unfortunately common for gibbons to be misidentified and housed together. For example, some collections' supposedly pure breeding pairs were actually mixed pairs or hybrids from previous mixed pairs. The hybrid offspring were sent to other gibbon breeders and led to further hybridization in captive gibbons. Within-genus hybrids also occur in wild gibbons where the ranges overlap (Agile Gibbons and Pileated Gibbons x Lar Gibbons, Agile Gibbons x Müller's Bornean Gibbon, Yellow-cheeked Gibbons x Northern White-cheeked Gibbons).

Intergeneric gibbon hybridizations are only known to have occurred in captivity. Silvery Gibbons (Hylobates moloch) and Müller's Bornean Gibbon (H. muelleri) have hybridized with Siamangs (Symphalangus syndactylus) in captivity - a female Siamang produced hybrid "Siabon" offspring on two occasions when housed with a male gibbon; only one hybrid survived.

Anubis Baboons and Hamadryas Baboons have hybridized in the wild where their ranges meet. A Rheboon is a captive-bred Rhesus Macaque/Hamadryas Baboon hybrid with a baboon-like body shape and macaque-like tail.

Different macaque species can interbreed. In "The Variation Of Animals And Plants Under Domestication" Charles Darwin wrote: ''A Macacus, according to Flourens, bred in Paris; and more than one species of this genus has produced young in London, especially the Macacus rhesus, which everywhere shows a special capacity to breed under confinement. Hybrids have been produced both in Paris and London from this same genus. The Japanese Macaque (Macaca fuscata) has interbred with the introduced Taiwanese Macacque (M. cyclopis) when the latter escaped into the wild from private zoos.

Various hybrid monkeys are bred within the pet trade, for example:

• Hybrid capuchin monkeys e.g. Tufted Capuchin (Cebus apella) x Weeper Capuchin (C. olivaceus'')
• Liontail Macaque x Pigtail Macaque hybrids
• Rhesus Macaque x Stumptail Macaque hybrids.

Among Old World monkeys, natural hybridization is not uncommon. There numerous field reports of hybrid monkeys and detailed studies of zones where species overlap and hybrids occur.

Among the great apes, Sumatran and Bornean orangutans are considered separate species with anatomical differences, producing sterile or poorly fertile hybrids. Hybrid orangutans are genetically weaker, with lower survival rates than pure animals.

Legal status

• Primatology

References

External links

• High-Resolution Cytoarchitectural Primate Brain Atlases
• Primate Info Net
• Primates in scientific experimentation
• Primate Research Institute, Kyoto University
• href="http://webdrive.service.emory.edu/groups/research/chimpanzee-cognition/CCL/ethogram/spec_laugh.jpg&imgrefurl=http://webdrive.service.emory.edu/groups/research/chimpanzee-cognition/CCL/ethogram.htm&h=382&w=784&sz=94&hl=en&start=6&tbnid=SzTd6o7BvU2mUM:&tbnh=70&tbnw=143&prev=/images%3Fq%3DChimpanzee%2Blaughter%26svnum%3D10%26hl%3Den%26lr%3D%26rls%3DHPIA,HPIA:2006-24,HPIA:en%26sa%3DN">http://webdrive.service.emory.edu/groups/research/chimpanzee-cognition/CCL/ethogram/spec_laugh.jpg&imgrefurl=http://webdrive.service.emory.edu/groups/research/chimpanzee-cognition/CCL/ethogram.htm&h=382&w=784&sz=94&hl=en&start=6&tbnid=SzTd6o7BvU2mUM:&tbnh=70&tbnw=143&prev=/images%3Fq%3DChimpanzee%2Blaughter%26svnum%3D10%26hl%3Den%26lr%3D%26rls%3DHPIA,HPIA:2006-24,HPIA:en%26sa%3DN Chimpanzee Facial Expression & Vocalizations
• EUPRIM-Net: European Primate Network
• A chimpanzee laughter sample.
• Ape differences from monkeys.
• Images of Primates.
• PrimateImages: Natural History Collection