Common characteristics of modern bears include large bodies with stocky legs, long snouts, small rounded ears, shaggy hair, plantigrade paws with five nonretractile claws, and short tails.

With their powerful physical presence, they play a prominent role in the arts, mythology, and other cultural aspects of various human societies.

[16] European genera morphologically very similar to Allocyon, and to the much younger American Kolponomos (about 18 Mya),[17] are known from the Oligocene, including Amphicticeps and Amphicynodon.

[27][28] The New World short-faced bears (Tremarctinae) differentiated from Ursinae following a dispersal event into North America during the mid-Miocene (about 13 Mya).

[16] The subfamily Ursinae experienced a dramatic proliferation of taxa about 5.3–4.5 Mya, coincident with major environmental changes; the first members of the genus Ursus appeared around this time.

The sloth bear is a modern survivor of one of the earliest lineages to diverge during this radiation event (5.3 Mya); it took on its peculiar morphology, related to its diet of termites and ants, no later than by the early Pleistocene.

By 3–4 Mya, the species Ursus minimus appears in the fossil record of Europe; apart from its size, it was nearly identical to today's Asian black bear.

One is all species of bears are classified in seven subfamilies as adopted here and related articles: Amphicynodontinae, Hemicyoninae, Ursavinae, Agriotheriinae, Ailuropodinae, Tremarctinae, and Ursinae.

Pandas are unique in having a bony extension on the wrist of the front feet which acts as a thumb, and is used for gripping bamboo shoots as the animals feed.

Polar bears have hollow, translucent guard hairs which gain heat from the sun and conduct it to the dark-colored skin below.

[47] While bears tend to be uniform in color, some species may have markings on the chest or face and the giant panda has a bold black-and-white pelage.

Polar bears appear to have secondarily re-evolved carnassial-like cheek teeth, as their diets have switched back towards carnivory.

[53] Bears have a fairly simple digestive system typical for carnivorans, with a single stomach, short undifferentiated intestines and no cecum.

[57] Extant bears are found in sixty countries primarily in the Northern Hemisphere and are concentrated in Asia, North America, and Europe.

[58] They occur in a range of habitats which include tropical lowland rainforest, both coniferous and broadleaf forests, prairies, steppes, montane grassland, alpine scree slopes, Arctic tundra and in the case of the polar bear, ice floes.

[61] Brown and American black bears are generally diurnal, meaning that they are active for the most part during the day, though they may forage substantially by night.

The only times bears are encountered in groups are mothers with young or occasional seasonal bounties of rich food (such as salmon runs).

[67] They eat anything from leaves, roots, and berries to insects, carrion, fresh meat, and fish, and have digestive systems and teeth adapted to such a diet.

[57] For example, Asiatic black bears in Taiwan consume large numbers of acorns when these are most common, and switch to ungulates at other times of the year.

[68] When foraging for plants, bears choose to eat them at the stage when they are at their most nutritious and digestible, typically avoiding older grasses, sedges and leaves.

[80] Fish are an important source of food for some species, and brown bears in particular gather in large numbers at salmon runs.

Staring is an aggressive act and the facial markings of spectacled bears and giant pandas may help draw attention to the eyes during agonistic encounters.

Dominance between bears is asserted by making a frontal orientation, showing the canine teeth, muzzle twisting and neck stretching.

A male bear may visit a female continuously over a period of several days or weeks, depending on the species, to test her reproductive state.

[113] If they have stored enough body fat, their muscles remain in good condition, and their protein maintenance requirements are met from recycling waste urea.

A study of American black bears found seventeen species of endoparasite including the protozoan Sarcocystis, the parasitic worm Diphyllobothrium mansonoides, and the nematodes Dirofilaria immitis, Capillaria aerophila, Physaloptera sp., Strongyloides sp.

In general, these two species inhabit remote areas with little interaction with humans, and the main non-natural causes of mortality are hunting, trapping, road-kill and depredation.

[128][129] In poorer rural regions, attitudes may be more shaped by the dangers posed by bears, and the economic costs they cause to farmers and ranchers.

The image of the mother bear was prevalent throughout societies in North America and Eurasia, based on the female's devotion and protection of her cubs.

[139] A widespread belief among cultures of North America and northern Asia associated bears with shaman; this may be based on the solitary nature of both.