Primate

iPrimates Fossil range: Latest Cretaceous - Recent
Olive Baboon, an Old World monkey
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Subclass: Eutheria (unranked) Euarchontoglires Superorder: Euarchonta Order: Primates Linnaeus, 1758
Families
15, See classification

A primate (L. prima, first) 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 latter category including humans. The English singular primate is a back-formation from the Latin name Primates, which itself was the plural of the Latin primas ("one of the first, excellent, noble"). Primates are found all over the world. Non-human primates occur mostly in Central and South America, Africa, and southern Asia. A few species exist as far north in the Americas as southern Mexico, and as far north in Asia as northern Japan.

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.

Physical description

All primates have five fingers (pentadactyly), a generalized dental pattern, and a primitive (unspecialized) body plan. Another distinguishing feature of primates is fingernails. Opposing thumbs are also a characteristic primate feature, but are not limited to this order; opossums, for example, also have opposing thumbs. 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. Forward-facing color binocular vision was also useful for the brachiating ancestors of humans, particularly for finding and collecting food, although recent studies suggest it was more useful in courtship. All primates, even those that lack the features typical of other primates (like lorises), share eye orbit characteristics, such as a postorbital bar, that distinguish them from other taxonomic orders.

Old World species (apes and some monkeys) tend to have significant sexual dimorphism. This is characterized most in size difference, with males being up to a bit more than twice as heavy as females. This dimorphism is a result of a polygynous mating system where there is significant pressure to attract and defend multiple mates. New World species form pair bonds, and so these species (including tamarins and marmosets) generally do not show a significant size difference between the sexes.

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 the Rhesus Macaque and the Hanuman Langur, are hemerophile species and cities and villages have become their typical habitat.

Classification and evolution

Close relations

The Primate order lies in a tight clustering of related orders (the Euarchontoglires) within the Eutheria, a subclass of Mammalia. Recent molecular genetic research on primates, flying lemurs, and treeshrews has shown that the two species of flying lemur (Dermoptera) are more closely related to the primates than the treeshrews of the order Scandentia, even though the treeshrews were at one time considered primates. These three orders make up the Euarchonta clade. This clade combines with the Glires clade (made up of the Rodentia and Lagomorpha) to form the Euarchontoglires clade. Variously, both Euarchonta and Euarchontoglires are ranked as superorders. Also, some scientists consider Dermoptera a suborder of Primates and call the "true" primates the suborder Euprimates.

Euarchontoglires	Glires Rodentia (rodents) Lagomorpha (rabbits, hares, pikas) Euarchonta Scandentia (treeshrews) Dermoptera (flying lemurs) †Plesiadapiformes Primates

Classification

Ring-tailed Lemur, a strepsirrhine primate

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. Some classification schemes wrap the Lepilemuridae into the Lemuridae and the Galagidae into the Lorisidae, yielding a three-two family split instead of the four-three split as presented here. Other lineages of lower primates inhabited Earth. During the Eocene, most of the northern continents were dominated by two dominant groups, the adapids and the omomyids. The former is considered a member of Strepsirrhini, but it does not have a tooth-comb like modern lemurs. The latter was related closely to tarsiers, monkeys, and apes. Adapids survived until 10 mya; omomyids on the other hand perished 20 million years earlier.

The Aye-aye is difficult to place in Strepsirrhini. Its family, Daubentoniidae, could be a lemuriform primate and its ancestors split from lemur line more recently than the lemurs and lorises split, about 50 mya. Otherwise it is sister to all of the other strepsirrhines, in which case in evolved away from the main strepsirrhine line between 50 and 63 mya.

Emperor Tamarin, a New World monkey

The suborder Haplorrhini, the "dry-nosed" primates, is composed of two sister clades. The prosimian tarsiers in family Tarsiidae (monotypic in its own infraorder Tarsiiformes), represent the most primitive division at about 58 mya. The Simiiformes infraorder contains the two parvorders: the New World monkeys in one, and the Old World monkeys, humans and the other apes in the other. This division happened about 40 mya. However about 30 mya, three groups split from the main haplorrhine lineage. One group stayed in Asia and are closest in kin to the "dawn monkey" Eosimias. The second stayed in Africa, where they developed into the Old World primates. The third rafted to South America to become the New World monkeys. Mysteriously the aboriginal Asian Haplorrhini vanished from record once Africa collided with Eurasia 24 mya. Apes and monkeys spread into Europe and Asia. Close behind came lorises and tarsiers, also African castaways. The first hominid fossils were discovered in Northern Africa and date back 7 mya. Modern humans did not appear until 0.2 mya, eventually becoming the most prevalent primate and mammal on Earth.

The discovery of new species happens at a rate of a few new species each year, and the evaluation of current populations as distinct species is in flux. Colin Groves lists about 350 species of primates in Primate Taxonomy in 2001. The recently published third edition of Mammal Species of the World (2005) lists 376 species. But even MSW3's list falls short of current understanding as its collection cutoff was in 2003, and a number publications since MSW3 push the number of species up to 404. Notable new species not listed in MSW3 include the Bemaraha Woolly Lemur (Avahi cleesei) (named after British actor and lemur enthusiast John Cleese) and the GoldenPalace.com Monkey (whose name was put up for auction).

Extant primate families

• 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 (134 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
• Australopithecus, ape-like human ancestor
• Branisella boliviana, an early New World monkey
• Dryopithecus, an early ape
• Eosimias, an early catarrhine
• Sahelanthropus tchadensis, a possible ancestor of humans
• Aegyptopithecus zeuxis, an early haplorrhine
• Pliopithecus, ancestor of the modern gibbons
• Gigantopithecus, the largest ape
• Godinotia, an adapid
• Megaladapis, a giant lemur
• Notharctus, an adapid
• Plesiopithecus teras, a relative of lorises and galagos
• Protopithecus brasiliensis, a giant New World monkey
• Sivapithecus, an early ape
• Tielhardina, the earliest haplorrhines
• Victoriapithecus, an early Old World monkey
• Pierolapithecus catalaunicus, a possible ancestor of large apes

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 have only 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 2 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

Monkeys imported for experimentation in a crate. Credit: BUAV

Humans are recognized as persons and protected in law by the United Nations Universal Declaration of Human Rights and by all governments, though to varying degrees. Non-human primates are not classified as persons, which means their individual interests have no formal recognition or protection. The status of non-human primates has generated much debate, particularly through the Great Ape Project which argues for their personhood.

Thousands of primates are used every year around the world in scientific experiments because of their psychological and physiological similarity to humans. Chimpanzees, baboons, marmosets, macaques, and green monkeys are most commonly used in these experiments. In the European Union, around 10,000 were used in 2004, with 4,652 experiments conducted on 3,115 non-human primates in the UK alone in 2005. As of 2004, 3,100 non-human primates were living in captivity in the United States, in zoos, circuses, and laboratories, 1,280 of them being used in experiments. European campaign groups such as the BUAV are seeking a ban on all primate use in experiments as part of the European Union's current review of existing law on animal experimentation.

Laughter in primates

Laughter might not be confined or unique to humans, despite Aristotle's observation that "only the human animal laughs". The differences between chimpanzee and human laughter may be the result of adaptations that have evolved to enable human speech. However, 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 are not really laughing in the same way that we 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 also known as pygmy chimpanzees 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. Discovery 2003A chimpanzee laughter sample. Goodall 1968 & Parr 2005

See also

• Arboreal theory
• Primatology
• Laughter

References

• Primates in Question (Smithsonian Institute Press, 2003), Robert W. Shumaker & Benjamin B. Beck (ISBN 1-58834-176-3 )

External links

• High-Resolution Cytoarchitectural Primate Brain Atlases
• Primate Info Net
• Primates in scientific experimentation
• Primate Research Institute, Kyoto University
• Chimpanzee Facial Expression & Vocalizations

Extant mammal orders by subclass

Australosphenida: Monotremata

Marsupialia: Didelphimorphia · Paucituberculata · Microbiotheria · Notoryctemorphia · Dasyuromorphia · Peramelemorphia · Diprotodontia

Placentalia: Afrosoricida · Macroscelidea · Tubulidentata · Hyracoidea · Proboscidea · Sirenia · Cingulata · Pilosa · Scandentia · Dermoptera · Primates · Rodentia · Lagomorpha · Insectivora · Chiroptera · Pholidota · Carnivora · Perissodactyla · Artiodactyla · Cetacea