Zoopharmacognosy is a behaviour in which non-human animals self-medicate by selecting and ingesting or topically applying plants, soils and psychoactive drugs to prevent or reduce the harmful effects of pathogens and toxins. The term derives from Greek roots zoo and gnosy. An example of zoopharmacognosy occurs. However, the behaviour is more diverse than this. Animals ingest or apply non-foods such as clay and toxic plants and invertebrates to prevent parasitic infestation or poisoning. Whether animals self-medicate remains a somewhat controversial subject because early evidence is circumstantial or anecdotal, more recent examinations have adopted an experimental, hypothesis-driven approach; the methods by which animals self-medicate vary, but can be classified according to function as prophylactic or therapeutic. The behaviour is believed to have widespread adaptive significance. In 1978, Janzen suggested that vertebrate herbivores might benefit medicinally from the secondary metabolites in their plant food.
In 1993, the term "zoopharmacognosy" was coined, derived from the Greek roots zoo and gnosy. The term gained popularity from academic works and in a book by Cindy Engel entitled Wild Health: How Animals Keep Themselves Well and What We Can Learn from Them; the anti-parasitic effect of zoopharmacognosy could occur by at least two mechanisms. First, the ingested material may have pharmacological antiparasitic properties such that phytochemicals decrease the ability of worms to attach to the mucosal lining of the intestines, or chemotaxis attracts worms into the folds of leaves. Many ingested plants during purported zoopharmacognosy have a consistent physical property, e.g. the rough surface of the leaves sports many hooked and spiky hairs. So, parasites may became attached to the bristly surface or the coarse structure may function as a rasping plug, dislodging parasites from the intestines; the second possible mode of action is the material may initiate a purging response of the gastrointestinal tract by inducing diarrhoea.
This decreases gut transit time, causes worm expulsion and interrupts the life cycle of parasites. This, or a similar, mechanism could explain undigested grass in the faeces of various animals such as birds and primates; some animals ingest or apply the substance when they appear to be well, suggesting the behaviour is preventative or prophylactic. In other cases, animals ingest or apply the substance when unwell, suggesting the behaviour is therapeutic or curative. There are three methods of self-medication, ingestion, absorption, or topical application. Many examples of zoopharmacognosy involve an animal ingesting a substance with medicinal properties. Ants infected with Beauveria bassiana, a fungus, selectively consume harmful substances upon exposure to a fungal pathogen, yet avoid these in the absence of infection. Great apes consume plants that have no nutritional values but which have beneficial effects on gut acidity or combat intestinal parasitic infection. Chimpanzees sometimes select bitter leaves for chewing.
Parasite infection drops noticeably after chimpanzees chew leaves of pith, which have anti-parasitic activity against schistosoma and Leishmania. Chimpanzees don't consume this plant on a regular basis, but when they do eat it, it is in small amounts by individuals that appear ill. Jane Goodall witnessed chimpanzees eating particular bushes to make themselves vomit. There are reports that chimpanzees swallow whole leaves of particular rough-leaved plants such as Aneilema aequinoctiale. Chimpanzees sometimes eat the leaves of the herbaceous Desmodium gangeticum. Undigested, non-chewed leaves were recovered in 4% of faecal samples of wild chimpanzees and clumps of sharp-edged grass leaves in 2%; the leaves have a rough surface or sharp-edges and the fact they were not chewed and excreted whole indicates they were not ingested for nutritional purposes. Furthermore, this leaf-swallowing was restricted to the rainy season when parasite re-infections are more common, parasitic worms were found together with the leaves.
Chimpanzees and gorillas eat the fruits of Aframomum angustifolium. Laboratory assays of homogenized fruit and seed extracts show significant anti-microbial activity. Illustrating the medicinal knowledge of some species, apes have been observed selecting a particular part of a medicinal plant by taking off leaves and breaking the stem to suck out the juice. Anubis baboons and hamadryas baboons in Ethiopia use fruits and leaves of Balanites aegyptiaca to control schistosomiasis, its fruits contain diosgenin, a hormone precursor that hinders the development of schistosomes. African elephants self-medicate to induce labour by chewing on the leaves of a particular tree from the family Boraginaceae. White-nosed coatis in Panama take the menthol-scented resin from freshly scraped bark of Trattinnickia aspera and vigorously rub it into their own fur or that of other coatis to kill ectoparasites such as fleas and lice, as well as biting insects such as mosquitoes. Domestic cats and dogs of
The orangutans are three extant species of great apes native to Indonesia and Malaysia. Orangutans are only found in the rainforests of Borneo and Sumatra. Classified in the genus Pongo, orangutans were considered to be one species. From 1996, they were divided into two species: the Sumatran orangutan. In November 2017 it was reported. Genomic comparisons show that the Tapanuli orangutan separated from the Sumatran orangutan about 3.4 million years ago. The Tapanuli orangutan separated from the Bornean orangutan much about 670,000 years ago; the orangutans are the only surviving species of the subfamily Ponginae, which included several other species, such as the three extinct species of the genus Gigantopithecus, including the largest known primate, Gigantopithecus blacki. The ancestors of the Ponginae split from the main ape line in Africa 16 to 19 million years ago and spread into Asia. Orangutans spend most of their time in trees, their hair is reddish-brown, instead of the black hair typical of chimpanzees and gorillas.
Males and females differ in appearance. Dominant adult males have distinctive cheek pads and produce long calls that attract females and intimidate rivals. Younger males do not resemble adult females. Orangutans are the most solitary of the great apes, with social bonds occurring between mothers and their dependent offspring, who stay together for the first two years. Fruit is the most important component of an orangutan's diet, they can live over 30 years in both the captivity. Orangutans are among the most intelligent primates; the apes have been extensively studied for their learning abilities. There may be distinctive cultures within populations. Field studies of the apes were pioneered by primatologist Birutė Galdikas. All three orangutan species are considered to be critically endangered. Human activities have caused severe declines in ranges. Threats to wild orangutan populations include poaching, habitat destruction as a result of palm oil cultivation, the illegal pet trade. Several conservation and rehabilitation organisations are dedicated to the survival of orangutans in the wild.
The name "orangutan" is derived from the Malay and Indonesian words orang meaning "person" and hutan meaning "forest", thus "person of the forest". The Malay words used to refer to the ape are maias and mawas, but it is unclear if those words refer to just orangutans, or to all apes in general; the first attestation of the word orangutan to name the Asian ape is in Dutch physician Jacobus Bontius' 1631 Historiae naturalis et medicae Indiae orientalis – he reported that Malays had informed him the ape was able to talk, but preferred not to "lest he be compelled to labour". The word appeared in several German-language descriptions of Indonesian zoology in the 17th century; the origin of the word comes from the Banjarese variety of Malay. Cribb et al. suggest that Bontius' account referred not to apes but rather to humans suffering some serious medical condition and that his use of the word was misunderstood by Nicolaes Tulp, the first to use the term in a publication. The word was first attested in English in 1691 in the form orang-outang, variants with -ng instead of -n as in the Malay original are found in many languages.
This spelling has remained in use in English up to the present, but has come to be regarded as incorrect. The loss of "h" in Utan and the shift from n to -ng has been taken to suggest that the term entered English through Portuguese. In 1869, British naturalist Alfred Russel Wallace, co-creator of modern evolutionary theory, published his account of Malaysia's wildlife: The Malay Archipelago: The Land of the Orang-Utan and the Bird of Paradise; the name of the genus, comes from a 16th-century account by Andrew Battel, an English sailor held prisoner by the Portuguese in Angola, which describes two anthropoid "monsters" named Pongo and Engeco. He is now believed to have been describing gorillas, but in the 18th century, the terms orangutan and pongo were used for all great apes. Lacépède used the term Pongo for the genus following the German botanist Friedrich von Wurmb who sent a skeleton from the Indies to Europe. Battel's "Pongo", in turn, is from the Kongo word mpongi or other cognates from the region: Lumbu pungu, Vili mpungu, or Yombi yimpungu.
The three orangutan species are the only extant members of the subfamily Ponginae. This subfamily included the extinct genera Lufengpithecus, which lived in southern China and Thailand 2–8 mya, Sivapithecus, which lived India and Pakistan from 12.5 mya until 8.5 mya. These apes lived in drier and cooler environments than orangutans do today. Khoratpithecus piriyai, which lived in Thailand 5–7 mya, is believed to have been the closest known relative of the orangutans; the largest known primate, was a member of Ponginae and lived in China and Vietnam from 5 mya to 100,000 years ago. Within apes, the gibbons diverged during the early Miocene and the orangutans split from the African great ape lineage betwe
A hedgehog is any of the spiny mammals of the subfamily Erinaceinae, in the eulipotyphlan family Erinaceidae. There are seventeen species of hedgehog in five genera found through parts of Europe and Africa, in New Zealand by introduction. There are no living species native to the Americas. Hedgehogs share distant ancestry with shrews, with gymnures being the intermediate link, they have changed little over the last 15 million years. Like many of the first mammals, they have adapted to a nocturnal way of life, their spiny protection resembles that of the unrelated porcupines, which are rodents, echidnas, a type of monotreme. The name hedgehog came into use around the year 1450, derived from the Middle English heyghoge, from heyg, because it frequents hedgerows, hoge, from its piglike snout. Other names include urchin and furze-pig. Hedgehogs are recognized by their spines, which are hollow hairs made stiff with keratin, their spines are not poisonous or barbed and unlike the quills of a porcupine, do not detach from their bodies.
However, the immature animal's spines fall out as they are replaced with adult spines. This is called "quilling". Spines can shed when the animal is diseased or under extreme stress. A defense that all species of hedgehogs possess is the ability to roll into a tight ball, causing all of the spines to point outwards; the hedgehog's back contains two large muscles. When the creature is rolled into a ball, the quills on the back protect the tucked face and belly, which are not quilled. Since the effectiveness of this strategy depends on the number of spines, some desert hedgehogs that evolved to carry less weight are more to flee or attack, ramming an intruder with the spines; the various species are prey to different predators: while forest hedgehogs are prey to birds and ferrets, smaller species like the long-eared hedgehog are prey to foxes and mongooses. Hedgehogs are nocturnal, though some species can be active during the day. Hedgehogs sleep for a large portion of the day under bushes, rocks, or most in dens dug in the ground, with varying habits among the species.
All wild hedgehogs can hibernate, though not all do, depending on temperature and abundance of food. Hedgehogs are vocal and communicate through a combination of grunts, snuffles and/or squeals, depending on species. Hedgehogs perform a ritual called anointing; when the animal encounters a new scent, it will lick and bite the source form a scented froth in its mouth and paste it on its spines with its tongue. The purpose of this habit is unknown, but some experts believe anointing camouflages the hedgehog with the new scent of the area and provides a possible poison or source of infection to predators poked by their spines. Anointing is sometimes called anting because of a similar behavior in birds. Like opossums and moles, hedgehogs have some natural immunity against some snake venom through the protein erinacin in the animal's muscular system, although it is available only in small amounts and a viper bite may still be fatal. In addition, hedgehogs are one of four known mammalian groups with mutations that protect against another snake venom, α-neurotoxin.
Pigs, honey badgers and hedgehogs all have mutations in the nicotinic acetylcholine receptor that prevent the snake venom α-neurotoxin from binding, though those mutations developed separately and independently. The olfactory regions have not been studied in the hedgehog. In mammals, the olfactory part of the brain is covered by neopallium; this difficulty is not insurmountable. Tests have suggested. Although traditionally classified in the now abandoned order Insectivora, hedgehogs are omnivorous, they feed on insects, snails and toads, bird eggs, mushrooms, grass roots, berries and watermelons. Berries constitute a major part of an Afghan hedgehog's diet in early spring after hibernation. During hibernation, the body temperature of a hedgehog can decrease to about 2 °C; when the animal awakes from hibernation, the body temperature rises from 2–5 °C back to its normal 30–35 °C body temperature. Depending on the species, the gestation period is 35–58 days; the average litter is 5 -- 6 for smaller ones.
As with many animals, it is not unusual for an adult male hedgehog to kill newborn males. Hedgehogs have a long lifespan for their size. Larger species of hedgehogs live 4–7 years in the wild, smaller species live 2–4 years, compared to a mouse at 2 years and a large rat at 3–5 years. Lack of predators and controlled diet contribute to a longer lifespan in captivity. Hedgehogs are born blind with a protective membrane covering their quills, which dries and shrinks over the next several hours; the quills emerge through the skin after they have been cleaned. Hedgehog bones have been found in the pellets of the European eagle owl. In Britain, the main predator is the badger. European hedgehog populations in the United Kingdom are lower in areas where badgers are numerous, British hedgehog rescue societies will not release hedgehogs into known badger territories. Badgers compete with hedgehogs for food; the most common p
A herbivore is an animal anatomically and physiologically adapted to eating plant material, for example foliage or marine algae, for the main component of its diet. As a result of their plant diet, herbivorous animals have mouthparts adapted to rasping or grinding. Horses and other herbivores have wide flat teeth that are adapted to grinding grass, tree bark, other tough plant material. A large percentage of herbivores have mutualistic gut flora that help them digest plant matter, more difficult to digest than animal prey; this flora is made up of cellulose-digesting bacteria. Herbivore is the anglicized form of a modern Latin coinage, cited in Charles Lyell's 1830 Principles of Geology. Richard Owen employed the anglicized term in an 1854 work on fossil skeletons. Herbivora is derived from the Latin herba meaning a small plant or herb, vora, from vorare, to eat or devour. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants and photosynthesizing bacteria.
More organisms that feed on autotrophs in general are known as primary consumers. Herbivory is limited to animals that eat plants. Fungi and protists that feed on living plants are termed plant pathogens, while fungi and microbes that feed on dead plants are described as saprotrophs. Flowering plants that obtain nutrition from other living plants are termed parasitic plants. There is, however, no single exclusive and definitive ecological classification of consumption patterns. In zoology, an herbivore is an animal, adapted to eat plant matter. Our understanding of herbivory in geological time comes from three sources: fossilized plants, which may preserve evidence of defence, or herbivory-related damage. Although herbivory was long thought to be a Mesozoic phenomenon, fossils have shown that within less than 20 million years after the first land plants evolved, plants were being consumed by arthropods. Insects fed on the spores of early Devonian plants, the Rhynie chert provides evidence that organisms fed on plants using a "pierce and suck" technique.
During the next 75 million years, plants evolved a range of more complex organs, such as roots and seeds. There is no evidence of any organism being fed upon until the middle-late Mississippian, 330.9 million years ago. There was a gap of 50 to 100 million years between the time each organ evolved and the time organisms evolved to feed upon them. Further than their arthropod status, the identity of these early herbivores is uncertain. Hole feeding and skeletonisation are recorded in the early Permian, with surface fluid feeding evolving by the end of that period. Herbivory among four-limbed terrestrial vertebrates, the tetrapods developed in the Late Carboniferous. Early tetrapods were large amphibious piscivores. While amphibians continued to feed on fish and insects, some reptiles began exploring two new food types and plants; the entire dinosaur order ornithischia was composed with herbivores dinosaurs. Carnivory was a natural transition from insectivory for medium and large tetrapods, requiring minimal adaptation.
In contrast, a complex set of adaptations was necessary for feeding on fibrous plant materials. Arthropods evolved herbivory in four phases, changing their approach to it in response to changing plant communities. Tetrapod herbivores made their first appearance in the fossil record of their jaws near the Permio-Carboniferous boundary 300 million years ago; the earliest evidence of their herbivory has been attributed to dental occlusion, the process in which teeth from the upper jaw come in contact with teeth in the lower jaw is present. The evolution of dental occlusion led to a drastic increase in plant food processing and provides evidence about feeding strategies based on tooth wear patterns. Examination of phylogenetic frameworks of tooth and jaw morphologes has revealed that dental occlusion developed independently in several lineages tetrapod herbivores; this suggests that evolution and spread occurred within various lineages. Herbivores form an important link in the food chain because they consume plants in order to digest the carbohydrates photosynthetically produced by a plant.
Carnivores in turn consume herbivores for the same reason, while omnivores can obtain their nutrients from either plants or animals. Due to a herbivore's ability to survive on tough and fibrous plant matter, they are termed the primary consumers in the food cycle. Herbivory and omnivory can be regarded as special cases of Consumer-Resource Systems. Herbivores come in all sizes in the animal kingdom, they include aquatic and non-aquatic vertebrates. They can be large, like an elephant. Many herbivores found living in close proximity to humans, such as rodents, cows and camels. Two herbivore feeding strategies are browsing. For a terrestrial mammal to be called a grazer, at least 90% of the forage has to be grass, for a browser at least 90% tree leaves and/or twigs. An intermediate feeding strategy is called "mixed-feeding". In their daily need to take up energy from forage, herbivores of different body mass may be selective in choosing their food. "Selective" means that herbivores may choose their forage source depending on, e.g. season or food avail
Carnivora is a diverse scrotiferan order that includes over 280 species of placental mammals. Its members are formally referred to as carnivorans, whereas the word "carnivore" can refer to any meat-eating organism. Carnivorans are the most diverse in size of any mammalian order, ranging from the least weasel, at as little as 25 g and 11 cm, to the polar bear, which can weigh up to 1,000 kg, to the southern elephant seal, whose adult males weigh up to 5,000 kg and measure up to 6.7 m in length. Carnivorans have teeth and claws adapted for catching and eating other animals. Many hunt in are social animals, giving them an advantage over larger prey; some carnivorans, such as cats and pinnipeds, depend on meat for their nutrition. Others, such as raccoons and bears, are more omnivorous, depending on the habitat; the giant panda is a herbivore, but feeds on fish and insects. The polar bear subsists on seals. Carnivorans are split into two suborders: Caniformia. Carnivorans all share the same arrangement of teeth in which the last upper premolar and the first lower molar have blade-like enamel crowns that work together as carnassial teeth to shear meat.
Carnivorans have had this arrangement for over 60 million years with many adaptions, these dental adaptions help identify carnivoran species and groupings of species. Carnivorans evolved in North America out of members of the family Miacidae about 42 million years ago, they soon split into dog-like forms. Their molecular phylogeny shows the extant Carnivora are a monophyletic group, the crown group of the Carnivoramorpha. Most carnivorans are terrestrial; the last premolar of the upper jaw and first molar of the lower are termed the carnassials or sectorial teeth. These blade-like teeth occlude with a scissor-like action for shredding meat. Carnassials are most developed in the Felidae and the least developed in the Ursidae. Carnivorans have two conical canines in each jaw; the only two exceptions to this are the sea otter, which has four incisors in the lower jaw, the sloth bear, which has four incisors in the upper jaw. The number of molars and premolars is variable between carnivoran species, but all teeth are rooted and are diphyodont.
Incisors are retained by carnivorans and the third incisor is large and sharp. Carnivorans have either four or five digits on each foot, with the first digit on the forepaws known as the dew claw, being vestigial in most species and absent in some; the superfamily Canoidea – Canidae, Mustelidae, Ursidae, Otariidae and Phocidae and the extinct family Amphicyonidae – are characterized by having nonchambered or chambered auditory bullae, nonretractable claws, a well-developed baculum. Most species are rather plain in coloration, lacking the flashy spotted or rosetted coats like many species of felids and viverrids have; this is because Canoidea tend to range in the temperate and subarctic biomes, although Mustelidae and Procyonidae have a few tropical species. Most are terrestrial. All families except the Canidae and a few species of Mustelidae are plantigrade. Diet is varied and most tend to be omnivorous to some degree, thus the carnassial teeth are less specialized. Canoidea have more molars in an elongated skull.
The superfamily Feloidea – Felidae, Herpestidae, Hyaenidae and Eupleridae, as well as the extinct family Nimravidae – have spotted, rosetted or striped coats, tend to be more brilliantly colored than their Canoidean counterparts. This is because these species tend to range in tropical habitats, although a few species do inhabit temperate and subarctic habitats. Many are arboreal or semiarboreal, the majority are digitigrade. Diet tends to be more carnivorous in the family Felidae, they have fewer teeth and shorter skulls, with much more specialized carnassials meant for shearing meat. Feliformia claws are retractile, or semiretractile; the terminal phalanx, with the claw attached, folds back in the forefoot into a sheath by the outer side of the middle phalanx of the digit, is retained in this position when at rest by a strong elastic ligament. In the hindfoot, the terminal joint or phalanx is retracted on to the top, not the side of the middle phalanx. Deep flexor muscles straighten the terminal phalanges, so the claws protrude from their sheaths, the soft "velvety" paw becomes converted into a formidable weapon.
The habitual retraction of the claws preserves their points from wear. The superfamily Pinnipedia, now considered to be part of Caniformia, are medium to large aquatic mammals. Being homeothermic marine mammals, pinni
An insectivore is a carnivorous plant or animal that eats insects. An alternative term is entomophage, which refers to the human practice of eating insects; the first insectivorous vertebrates were amphibians. When they evolved 400 million years ago, the first amphibians were piscivores, with numerous sharp conical teeth, much like a modern crocodile; the same tooth arrangement is however suited for eating animals with exoskeletons, thus the ability to eat insects is an extension of piscivory. At one time, insectivorous mammals were scientifically classified in an order called Insectivora; this order is now abandoned, as not all insectivorous mammals are related. Most of the Insectivora taxa have been reclassified. Although individually small, insects exist in enormous numbers - they number over a million described species and some of those species occur in enormous numbers. Accordingly, insects make up a large part of the animal biomass in all non-marine, non-polar environments, it has been estimated that the global insect biomass is in the region of 1012 kg with an estimated population of 1018 organisms.
Many creatures depend on insects as their primary diet, many that do not use insects as a protein supplement when they are breeding. Examples of insectivores include different kinds of species of carp, frogs, nightingales, echidnas, anteaters, aardvarks, aardwolfs and spiders. Large mammals are recorded as eating insects. Insects can be insectivores. Insectivory features to various degrees amongst primates, such as marmosets, tarsiers and aye-aye. There is some suggestion that the earliest primates were arboreal insectivores. Insectivorous plants are plants that derive some of their nutrients from trapping and consuming animals or protozoan; the benefit they derive from their catch varies considerably. As a rule, such animal food, however valuable it might be as a source of certain critically important minerals, is not the plants' major source of energy, which they derive from photosynthesis. Insectivorous plants might consume insects and other animal material trapped adventitiously, though most species to which such food represents an important part of their intake are often spectacularly, adapted to attract and secure adequate supplies.
Their prey animals but not comprise insects and other arthropods. Plants adapted to reliance on animal food use a variety of mechanisms to secure their prey, such as pitfalls, sticky surfaces, hair-trigger snaps, bladder-traps, entangling furriness, lobster-pot trap mechanisms. Known as carnivorous plants, they appear adapted to grow in places where the soil is thin or poor in nutrients nitrogen, such as acidic bogs and rock outcroppings. Insectivorous plants include the Venus flytrap, several types of pitcher plants, sundews, the waterwheel plant and many members of the Bromeliaceae; the list is far from complete, some plants, such as Roridula species, exploit the prey organisms in a mutualistic relationship with other creatures, such as resident organisms that contribute to the digestion of prey. In particular animal prey organisms supply carnivorous plants with nitrogen, but they are important sources of various other soluble minerals, such as potassium and trace elements that are in short supply in environments where the plants flourish.
This gives them a decisive advantage over other plants, whereas in nutrient-rich soils they tend to be out-competed by plants adapted to aggressive growth where nutrient supplies are not the major constraints. Technically these plants are not insectivorous, as they consume any animal that they can secure and consume. Most of those that do have such a restrictive diet, such as certain parasitoids and hunting wasps, are specialised to exploit particular species, not insects in general. Indeed, much as large mantids and spiders will do, the larger varieties of pitcher plant have been known to consume vertebrates such as small rodents and lizards. Charles Darwin wrote the first well-known treatise on carnivorous plants in 1875; the dictionary definition of insectivore at Wiktionary Entomophagy Insectivora List of feeding behaviours Consumer-resource systems
Bears are carnivoran mammals of the family Ursidae. They are classified as doglike carnivorans. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and in the Southern Hemisphere. Bears are found on the continents of North America, South America and Asia. Common characteristics of modern bears include large bodies with stocky legs, long snouts, small rounded ears, shaggy hair, plantigrade paws with five nonretractile claws, short tails. While the polar bear is carnivorous, the giant panda feeds entirely on bamboo, the remaining six species are omnivorous with varied diets. With the exception of courting individuals and mothers with their young, bears are solitary animals, they may have an excellent sense of smell. Despite their heavy build and awkward gait, they are adept runners and swimmers. Bears use shelters, such as logs, as their dens. Bears have been hunted since prehistoric times for their fur. With their powerful physical presence, they play a prominent role in the arts and other cultural aspects of various human societies.
In modern times, bears have come under pressure through encroachment on their habitats and illegal trade in bear parts, including the Asian bile bear market. The IUCN lists six bear species as vulnerable or endangered, least concern species, such as the brown bear, are at risk of extirpation in certain countries; the poaching and international trade of these most threatened populations are prohibited, but still ongoing. The English word "bear" comes from Old English bera and belongs to a family of names for the bear in Germanic languages, such as Swedish björn used as a first name; this form is conventionally said to be related to a Proto-Indo-European word for "brown", so that "bear" would mean "the brown one". However, Ringe notes that while this etymology is semantically plausible, a word meaning "brown" of this form cannot be found in Proto-Indo-European, he suggests instead that "bear" is from the Proto-Indo-European word *ǵʰwḗr- ~ *ǵʰwér "wild animal". This terminology for the animal originated as a taboo avoidance term: proto-Germanic tribes replaced their original word for bear—arkto—with this euphemistic expression out of fear that speaking the animal's true name might cause it to appear.
According to author Ralph Keyes, this is the oldest known euphemism. Bear taxon names such as Arctoidea and Helarctos come from the ancient Greek word ἄρκτος, meaning bear, as do the names "arctic" and "antarctic", from the constellation Ursa Major, the "Great Bear", prominent in the northern sky. Bear taxon names such as Ursidae and Ursus come from he-bear/she-bear; the female first name "Ursula" derived from a Christian saint's name, means "little she-bear". In Switzerland, the male first name "Urs" is popular, while the name of the canton and city of Bern is derived from Bär, German for bear; the Germanic name Bernard means "bear-brave", "bear-hardy", or "bold bear". The Old English name Beowulf is a kenning; the family Ursidae is one of nine families in the suborder Caniformia, or "doglike" carnivorans, within the order Carnivora. Bears' closest living relatives are the pinnipeds and musteloids. Modern bears comprise eight species in three subfamilies: Ailuropodinae and Ursinae. Nuclear chromosome analysis show that the karyotype of the six ursine bears is nearly identical, with each having 74 chromosomes, whereas the giant panda has 42 chromosomes and the spectacled bear 52.
These smaller numbers can be explained by the fusing of some chromosomes, the banding patterns on these match those of the ursine species, but differ from those of procyonids, which supports the inclusion of these two species in Ursidae rather than in Procyonidae, where they had been placed by some earlier authorities. The earliest members of Ursidae belong to the extinct subfamily Amphicynodontinae, including Parictis and the younger Allocyon, both from North America; these animals looked different from today's bears, being small and raccoon-like in overall appearance, with diets more similar to that of a badger. Parictis does not appear in Africa until the Miocene, it is unclear whether late-Eocene ursids were present in Eurasia, although faunal exchange across the Bering land bridge may have been possible during a major sea level low stand as early as the late Eocene and continuing into the early Oligocene. European genera morphologically similar to Allocyon, to the much younger American Kolponomos, are known from the Oligocene, including Amphicticeps and Amphicynodon.
There has been various morphological evidence linking amphicynodontines with pinnipeds, as both groups were semi-aquatic, otter-like mammals. In addition to the support of the pinniped–amphicynodontine clade, other morphological and some molecular evidence supports bears being the closet living relatives to pinnipeds; the raccoon-sized, dog-like Cephalogale is the oldest-known member of the subfamily Hemicyoninae, which first appeared during the middle Oligocene in Eurasia about 30 Mya