Instruct: Given a question, retrieve passages that can help answer the question.
Query: Are humans considered carnivores?
Various mammals are omnivorous in the wild, such as species of pigs, badgers, bears, coatis, civets, hedgehogs, opossums, skunks, sloths, squirrels, raccoons, chipmunks, mice, and rats. Hominidae, including humans and chimpanzees, are also omnivores.
Most bear species are omnivores, but individual diets can range from almost exclusively herbivorous to almost exclusively carnivorous, depending on what food sources are available locally and seasonally. Polar bears are classified as carnivores, both taxonomically (they are in the order Carnivora), and behaviorally (they subsist on a largely carnivorous diet). Depending on the species of bear, there is generally a preference for one class of food, as plants and animals are digested differently. Wolf subspecies (including wolves, dogs, dingoes, and coyotes) eat some plant matter, but they have a general preference and are evolutionarily geared towards meat. Also, the maned wolf is a canid whose diet is naturally 50% plant matter.
Their diet includes the fruit and seeds of local cactus plants, as well as beans of the mesquite plant. They do not only eat vegetation, and also consume insects, small rodents and carrion. They have a variety of predators including the bobcat, coyotes, as well as local snakes and domestic animals such as dogs and cats.
The general bite-and-retreat hypothesis has been criticised because of its bloodiness and because the struggling prey would have attracted any predators and scavengers in the area. The idea that a single animal would wound, release, and follow a prey animal has been counteracted more strongly. Cats rarely walk away from prey until they have eaten their fill and it would have risked being stolen by other predators.
Encounters between people and Kodiak bears have been very frequent since ancient times. Today, these encounters have become more common as a result of the increase in the human population in the region. Such encounters have included the hunting of bears by humans for their fur or meat, and, less commonly, attacks by bears upon humans. More recently, as conservation efforts have become more commonplace, concerns over the sustenance and stability of the Kodiak bear population have arisen. The IUCN classifies "Ursus arctos", the species to which the Kodiak belongs, as being of "least concern" in terms of endangerment or extinction. However, the IUCN does not differentiate between subspecies; therefore, it is unknown whether the Kodiak bear population is as healthy as is stated. As a result, the Alaska Department of Fish and Game, along with, to a lesser extent, the United States Fish and Wildlife Service, closely monitors the number of bears hunted in the state.
Carbohydrates are a common source of energy in living organisms; however, no single carbohydrate is an essential nutrient in humans. Humans are able to obtain all of their energy requirement from protein and fats, though the potential for some negative health effects of extreme carbohydrate restriction remains, as the issue has not been studied extensively yet. However, in the case of dietary fiber – indigestible carbohydrates which are not a source of energy – inadequate intake can lead to significant increases in mortality.
The image of the caveman is commonly associated with the Stone Age. For example, a 2003 documentary series showing the evolution of humans through the Stone Age was called "Walking with Cavemen", but only the last programme showed humans living in caves. While the idea that human beings and dinosaurs coexisted is sometimes portrayed in popular culture in cartoons, films and computer games, such as "The Flintstones", "One Million Years B.C." and "Chuck Rock", the notion of hominids and non-avian dinosaurs co-existing is not supported by any scientific evidence.
The fear of wolves has been pervasive in many societies, though humans are not part of the wolf's natural prey. How wolves react to humans depends largely on their prior experience with people: wolves lacking any negative experience of humans, or which are food-conditioned, may show little fear of people. Although wolves may react aggressively under provocation, such attacks are mostly limited to quick bites on extremities, and the attacks are not pressed. Predatory attacks (attacks by wolves treating humans as food) may be preceded by a long period of habituation, in which wolves gradually lose their fear of humans. The victims are repeatedly bitten on the head and face, and are then dragged off and consumed, unless the wolves are driven off. Such attacks typically occur only locally, and do not stop until the wolves involved are eliminated. Predatory attacks can occur at any time of the year, with a peak in the June–August period, when the chances of people entering forested areas (for livestock grazing or berry and mushroom picking) increase, though cases of non-rabid wolf attacks in winter have been recorded in Belarus, Kirov and Irkutsk oblasts, Karelia and Ukraine. Also, wolves with pups experience greater food stresses during this period.
On occasion, the bone of a fossilised predator is preserved well enough to retain recognizable proteins that belong to the species it consumed when alive. Stable isotope analysis of these proteins has shown that "Smilodon" preyed mainly on bison and horses, and occasionally ground sloths and mammoths, while "Homotherium" often preyed on young mammoths and other grazers such as pronghorn antelope and bighorn sheep when mammoths were not available.
Rodents make up the largest order of mammals, with over 40 percent of mammalian species. They have two incisors in the upper and lower jaw which grow continually and must be kept short by gnawing. Most rodents are small though the capybara, a rodent native to South America, can weigh up to 45 kg (100 lb).
The main predator of sun bears throughout its range by far is man. Commercial poaching of bears for the wildlife trade is a considerable threat in most countries. During surveys in Kalimantan between 1994 and 1997, interviewees admitted to hunting sun bears and indicated that sun bear meat is eaten by indigenous people in several areas in Kalimantan. High consumption of bear parts was reported to occur where Japanese or Korean expatriate employees of timber companies created a temporary demand. Traditional Chinese medicine (TCM) shops in Sarawak and Sabah offered sun bear gallbladders. Several confiscated sun bears indicated that live bears are also in demand for the pet trade.
The polar bear ("Ursus maritimus") is a hypercarnivorous bear whose native range lies largely within the Arctic Circle, encompassing the Arctic Ocean, its surrounding seas and surrounding land masses. It is a large bear, approximately the same size as the omnivorous Kodiak bear ("Ursus arctos middendorffi"). A boar (adult male) weighs around , while a sow (adult female) is about half that size. Although it is the sister species of the brown bear, it has evolved to occupy a narrower ecological niche, with many body characteristics adapted for cold temperatures, for moving across snow, ice and open water, and for hunting seals, which make up most of its diet. Although most polar bears are born on land, they spend most of their time on the sea ice. Their scientific name means "maritime bear" and derives from this fact. Polar bears hunt their preferred food of seals from the edge of sea ice, often living off fat reserves when no sea ice is present. Because of their dependence on the sea ice, polar bears are classified as marine mammals.
Although insects can be a problem, by far the biggest killer of carnivorous plants (besides human maltreatment) is grey mold ("Botrytis cinerea"). This thrives under warm, humid conditions and can be a real problem in winter. To some extent, temperate carnivorous plants can be protected from this pathogen by ensuring that they are kept cool and well ventilated in winter and that any dead leaves are removed promptly. If this fails, a fungicide is in order.
Now recognised as a member of the family Spinosauridae, "Baryonyx" affinities were obscure when it was discovered. Some researchers have suggested that "Suchosaurus cultridens" is a senior synonym (being an older name), and that "Suchomimus tenerensis" belongs in the same genus; subsequent authors have kept them separate. "Baryonyx" was the first theropod dinosaur demonstrated to have been piscivorous (fish-eating), as evidenced by fish scales in the stomach region of the holotype specimen. It may also have been an active predator of larger prey and a scavenger, since it also contained bones of a juvenile "Iguanodon". The creature would have caught and processed its prey primarily with its forelimbs and large claws. "Baryonyx" may have had semiaquatic habits, and coexisted with other theropod, ornithopod, and sauropod dinosaurs, as well as pterosaurs, crocodiles, turtles and fishes, in a fluvial environment.
"Phytoplankton are eaten by zooplankton - small animals which, like phytoplankton, drift in the ocean currents. The most abundant zooplankton species are copepods and krill: tiny crustaceans that are the most numerous animals on Earth. Other types of zooplankton include jelly fish and the larvae of fish, marine worms, starfish, and other marine organisms". In turn, the zooplankton are eaten by filter-feeding animals, including some seabirds, small forage fish like herrings and sardines, whale sharks, manta rays, and the largest animal in the world, the blue whale. Yet again, moving up the foodchain, the small forage fish are in turn eaten by larger predators, such as tuna, marlin, sharks, large squid, seabirds, dolphins, and toothed whales.
An American black bear has better eyesight and a better sense of hearing compared to humans. Their keenest sense is their sense of smell, which is about seven times greater than a domestic dog's. American black bears are excellent and strong swimmers, doing so for pleasure and to feed (largely on fish). They regularly climb trees to feed, escape enemies and hibernate. Four of the eight modern bear species are habitually arboreal (the most arboreal species, the American and Asian black bears and the sun bear, being fairly closely related). Their arboreal abilities tend to decline with age. American black bears may be active at any time of the day or night, although they mainly forage by night. American black bears living near human habitations tend to be more extensively nocturnal and American black bears living near brown bears tend to be more extensively diurnal. Their social behavior is somewhat similar to that of canids.
The mandrill is an omnivore. It usually consumes plants, of which it eats over a hundred species. It prefers to eat fruits, but will also eat leaves, lianas, bark, stems, and fibers. It also consumes mushrooms and soil. Carnivorously, mandrills mostly eat invertebrates, particularly ants, beetles, termites, crickets, spiders, snails, and scorpions. It will also eat eggs, and even vertebrates such as birds, tortoises, frogs, porcupines, rats, and shrews. Mandrills likely will eat larger vertebrates when they have the opportunity, such as juvenile bay duikers and other small antelope. Large prey are likely killed with a bite to the nape with the mandrill's long canines. One study found the mandrill's diet was composed of fruit (50.7%), seeds (26.0%), leaves (8.2%), pith (6.8%), flowers (2.7%), and animal foods (4.1%), with other foods making up the remaining (1.4%).
In general, humans can survive for two to eight weeks without food, depending on stored body fat. Survival without water is usually limited to three or four days. About 36 million humans die every year from causes directly or indirectly related to starvation. Childhood malnutrition is also common and contributes to the global burden of disease. However global food distribution is not even, and obesity among some human populations has increased rapidly, leading to health complications and increased mortality in some developed, and a few developing countries. Worldwide over one billion people are obese, while in the United States 35% of people are obese, leading to this being described as an "obesity epidemic." Obesity is caused by consuming more calories than are expended, so excessive weight gain is usually caused by an energy-dense diet.
Humans evolved to live as simple hunter-gatherers in small tribal bands. Contemporary humans now have a very different environment and way of life. This change makes present humans vulnerable to a number of health problems, termed "diseases of civilization" and "diseases of affluence". Stone-age humans evolved to live off the land, taking advantage of the resources that were readily available to them. Evolution is slow, and the rapid change from stone-age environments and practices to the world of today is problematic because we are still adapted to stone-age circumstances that no longer apply. This misfit has serious implications for our health. "Modern environments may cause many diseases such as deficiency syndromes like scurvy and rickets".)
All mammalian species produce milk, but the composition of milk for each species varies widely and other kinds of milk are often very different from human breast milk. As a rule, the milk of mammals that nurse frequently (including human babies) is less rich, or more watery, than the milk of mammals whose young nurse less often. Human milk is noticeably thinner and sweeter than cow's milk.
Foxes are often considered pests or nuisance creatures for their opportunistic attacks on poultry and other small livestock. Fox attacks on humans are not common.
Many foxes adapt well to human environments, with several species classified as "resident urban carnivores" for their ability to sustain populations entirely within urban boundaries. Foxes in urban areas can live longer and can have smaller litter sizes than foxes in non-urban areas. Urban foxes are ubiquitous in Europe, where they show altered behaviors compared to non-urban foxes, including increased population density, smaller territory, and pack foraging. Foxes have been introduced in numerous locations, with varying effects on indigenous flora and fauna.
The island has five land mammal species: pigs, deer, goats, cats, and rats. All these land mammals were introduced by humans. The Costa Rican government has vowed to control the populations of these animals, as they are harmful to the local ecosystems.
Some physiological carnivores consume plant matter and some physiological herbivores consume meat. From a behavioral aspect, this would make them omnivores, but from the physiological standpoint, this may be due to zoopharmacognosy. Physiologically, animals must be able to obtain both energy and nutrients from plant and animal materials to be considered omnivorous. Thus, such animals are still able to be classified as carnivores and herbivores when they are just obtaining nutrients from materials originating from sources that do not seemingly complement their classification. For example, it is well documented that some ungulates such as giraffes, camels, and cattle, will gnaw on bones to consume particular minerals and nutrients. Also, cats, which are generally regarded as obligate carnivores, occasionally eat grass to regurgitate indigestible material (such as hairballs), aid with hemoglobin production, and as a laxative.
Although dogs are most abundant and widely distributed terrestrial carnivores, the potential of feral and free-ranging dogs to compete with other large carnivores is limited by their strong association with humans. For example, a review of the studies in the competitive effects of dogs on sympatric carnivores did not mention any research on competition between dogs and wolves. Although wolves are known to kill dogs, they tend to live in pairs or in small packs in areas where they are highly persecuted, giving them a disadvantage facing large dog groups.
Many prehistoric mammals of the clade Carnivoramorpha (Carnivora and Miacoidea without Creodonta), along with the early order Creodonta, and some mammals of the even earlier order Cimolesta, were hypercarnivores. The earliest carnivorous mammal is considered to be "Cimolestes", which existed during the Late Cretaceous and early Paleogene periods in North America about 66 million years ago. Theropod dinosaurs such as "Tyrannosaurus rex" that existed during the late Cretaceous, although not mammals, were obligate carnivores.
It is remarkable the almost complete absence of carnivores, which are only represented by a few bones of "Ursus arctos", "Lynx pardinus" and "Canis lupus". The occurrence of carnivores in other sites, as in Boquete de Zafarraya, alternates with human presence in the stratigraphy. This event is interpreted as a seasonal occupation of the site by humans. When humans leave this habitat, carnivores take place of the site. Since this situation is not observed at Cave of the Angel, and moreover, there is no interruption in the stratigraphy of human presence, it is likely that a long term human occupation took place. In contrast, the existence of those few carnivore remains can be explained as the result of human consumption as so it happens with rabbit remains ("Oryctolagus cuniculus").