Bears are mammals of the family Ursidae. They are caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although only eight species of bears are extant, they are widespread, appearing in a wide variety of habitats throughout the Northern Hemisphere and partially in the Southern Hemisphere. Bears are found on the continents of North America, South America, Europe, and Asia. Common characteristics of modern bears include large bodies with stocky legs, long snouts, shaggy hair, plantigrade paws with five nonretractile claws, and short tails. The polar bear is mostly carnivorous, the giant panda feeds almost entirely on bamboo, and the remaining six species are omnivorous with varied diets. Except courting individuals and mothers with their young, bears are typically solitary animals. They are generally diurnal, but may be active during the night (nocturnal) or twilight (crepuscular) particularly around humans. Bears possess an excellent sense of smell and, despite their heavy build and awkward gait, are adept runners, climbers, and swimmers. In autumn, some bear species forage much fermented fruit, which affects their behaviour.[1] Bears den in caves and burrows; most species occupy their dens during the winter for a long period (up to 100 days) of sleep that resembles hibernation.[2] Bears have been hunted since prehistoric times for their meat and fur. With their tremendous physical presence and charisma, they play a prominent role in the arts, mythology, and other cultural aspects of various human societies. In modern times, the bears' existence has been pressured through the encroachment on their habitats and the illegal trade of bears and bear parts, including the Asian bile bear market. The IUCN lists six bear species as vulnerable or endangered, and even 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 that originate from an adjective meaning "brown".[3] In Scandinavia, the word for bear is björn (or bjørn), and is a relatively common given name for males. The use of this name is ancient and has been found mentioned in several runestone inscriptions.[4] The reconstructed Proto-Indo-European name of the bear is *h₂ŕ̥tḱos, whence Sanskrit r̥kṣa, Avestan arša, Greek ἄρκτος (arktos), Latin ursus, Welsh arth (whence perhaps "Arthur"), Albanian ari, Armenian արջ (arj). Also compared is Hittite ḫartagga-, the name of a monster or predator.[3] In the binomial name of the brown bear, Ursus arctos, Linnaeus simply combined the Latin and Greek names. The Proto-Indo-European (PIE) word for bear, *h₂ŕ̥tḱos seems to have been subject to taboo deformation or replacement in some languages (as was the word for wolf, wlkwos), resulting in the use of numerous unrelated words with meanings like "brown one" (English bruin) and "honey-eater" (Slavic medved).[5] Thus, some Indo-European language groups do not share the same PIE root. The giant panda's taxonomy (subfamily Ailuropodinae) has long been debated. Its original classification by Armand David in 1869 was within the bear genus Ursus, but in 1870, it was reclassified by Alphonse Milne-Edwards to the raccoon family.[14] In recent studies, the majority of DNA analyses suggest the giant panda has a much closer relationship to other bears and should be considered a member of the family Ursidae.[15] Estimates of divergence dates place the giant panda as the most ancient offshoot among living taxa within Ursidae, having split from other bears 17.9 to 22.1 Mya.[10] The red panda was included within Ursidae in the past. However, more recent research does not support such a conclusion, and instead places it in its own family Ailuridae, in superfamily Musteloidea along with Mustelidae, Procyonidae, and Mephitidae.[16][17][18] Multiple similarities between the two pandas, including the presence of false thumbs, are thus thought to represent an example of convergent evolution for feeding primarily on bamboo. Unlike their neighbors elsewhere, the brown bears of Alaska's ABC Islands evidently are more closely related to polar bears than to other brown bears in the world. Researchers Gerald Shields and Sandra Talbot of the University of Alaska Fairbanks Institute of Arctic Biology studied the DNA of several samples of the species and found their DNA is different from that of other brown bears. The discovery has shown, while all other brown bears share a brown bear as their closest relative, those of Alaska's ABC Islands differ and share their closest relation with the polar bear.[19] Also, the very rare Tibetan blue bear is a type of brown bear. This animal has never been photographed.[citation needed]

• published: 14 Dec 2013
• views: 2