ratio of word probabilities predicted from brain for cat and horse

cat	horse
top 10 words in brain distribution (in article): species animal bird female male fish breed human live food	top 10 words in brain distribution (in article): species animal horse wear female time male form live food
top 10 words in brain distribution (not in article): egg wolf ant genus bee lock nest fossil switch shark	top 10 words in brain distribution (not in article): bird egg fish card ant woman bee nest clothe snake
times more probable under cat 30 20 10 6 4 2.5 1.25 1 1.25 2.5 4 6 10 20 30 times more probable under horse (words not in the model)
The cat'" ("Felis catus"), also known as the domestic cat'" or "'house cat'" to distinguish it from other felines and felids, is a small predatory carnivorous species of crepuscular mammal that is valued by humans for its companionship and its ability to hunt vermin, snakes, scorpions, and other unwanted household pests. It has been associated with humans for at least 9,500 years. A skilled predator, the cat is known to hunt over 1,000 species for food. It can be trained to obey simple commands. Individual cats have also been known to learn on their own to manipulate simple mechanisms, such as doorknobs. Cats use a variety of vocalizations and types of body language for communication, including meowing, purring, hissing, growling, squeaking, chirping, clicking, and grunting. Cats may be the most popular pet in the world, with over 600 million in homes all over the world. They are also bred and shown as registered pedigree pets. This hobby is known as the "cat fancy." Until recently the cat was commonly believed to have been domesticated in ancient Egypt, where it was a cult animal. However a 2007 study found that the lines of descent of all house cats probably run through as few as five self-domesticating African Wildcats "(Felis silvestris lybica)" circa 8000 BC, in the Near East. Size. Cats typically weigh between 2.5 and 7 kg (5.5–16 pounds); however, some, such as the Maine Coon, can exceed. Some have been known to reach up to due to overfeeding. Conversely, very small cats (less than) have been reported. The largest cat ever was officially reported to have weighed in at about (46 lb 15.25 oz). The smallest cat ever officially recorded weighed around 3 lbs (1.36 kg). Cats average about in height and in head body length (males being larger than females), with tails averaging in length. Skeleton. Cats have 7 cervical vertebrae like almost all mammals, 13 thoracic vertebrae (humans have 12), 7 lumbar vertebrae (humans have 5), 3 sacral vertebrae like most mammals (humans have 5 because of their bipedal posture), and, except for Manx cats, 22 or 23 caudal vertebrae (humans have 3 to 5, fused into an internal coccyx). The extra lumbar and thoracic vertebrae account for the cat's enhanced spinal mobility and flexibility, compared with humans. The caudal vertebrae form the tail, used by the cat as a counterbalance to the body during quick movements. Cats also have free-floating clavicle bones, which allows them to pass their body through any space into which they can fit their heads. Mouth. Cats have highly specialized teeth for the killing of prey and the tearing of meat. The premolar and first molar together compose the carnassial pair on each side of the mouth, which efficiently functions to shear meat like a pair of scissors. While this is present in canids, it is highly developed in felines. The cat's tongue has sharp spines, or papillae, useful for retaining and ripping flesh from a carcass. These papillae are small backward-facing hooks that contain keratin which also assist in their grooming. As facilitated by their oral structure, cats use a variety of vocalizations and types of body language for communication, including meowing, purring, hissing, growling, squeaking, chirping, clicking, and grunting. Ears. Thirty-two individual muscles in each ear allow for a manner of directional hearing: a cat can move each ear independently of the other. Because of this mobility, a cat can move its body in one direction and point its ears in another direction. Most cats have straight ears pointing upward. Unlike dogs, flap-eared breeds are extremely rare (Scottish Folds are one such exceptional mutation.) When angry or frightened, a cat will lay back its ears, to accompany the growling or hissing sounds it makes. Cats also turn their ears back when they are playing, or to listen to a sound coming from behind them. The angle of cats' ears is an important clue to their mood. Legs. Cats, like dogs, are digitigrades. They walk directly on their toes, with the bones of their feet making up the lower part of the visible leg. Cats are capable of walking very precisely, because like all felines they directly register; that is, they place each hind paw (almost) directly in the print of the corresponding forepaw, minimizing noise and visible tracks. This also provides sure footing for their hind paws when they navigate rough terrain. Claws. Like nearly all members of family Felidae, cats have protractable claws. In their normal, relaxed position the claws are sheathed with the skin and fur around the toe pads. This keeps the claws sharp by preventing wear from contact with the ground and allows the silent stalking of prey. The claws on the forefeet are typically sharper than those on the hind feet. Cats can voluntarily extend their claws on one or more paws. They may extend their claws in hunting or self-defense, climbing, "kneading", or for extra traction on soft surfaces (bedspreads, thick rugs, etc.). It is also possible to make a cooperative cat extend its claws by carefully pressing both the top and bottom of the paw. The curved claws may become entangled in carpet or thick fabric, which may cause injury if the cat is unable to free itself. Most cats have five claws on their front paws, and four or five on their rear paws. Because of an ancient mutation, however, domestic and feral cats are prone to polydactylyism, (particularly in the east coast of Canada and north east coast of the United States) and may have six or seven toes. The fifth front claw (the dewclaw) is proximal to the other claws. More proximally, there is a protrusion which appears to be a sixth "finger". This special feature of the front paws, on the inside of the wrists, is the carpal pad, also found on the paws of big cats and dogs. It has no function in normal walking, but is thought to be an anti-skidding device used while jumping. Skin. Cats possess rather loose skin; this allows them to turn and confront a predator or another cat in a fight, even when it has a grip on them. This is also an advantage for veterinary purposes, as it simplifies injections. In fact, the lives of cats with kidney failure can sometimes be extended for years by the regular injection of large volumes of fluid subcutaneously, which serves as an alternative to dialysis. The particularly loose skin at the back of the neck is known as the "scruff", and is the area by which a mother cat grips her kittens to carry them. As a result, cats tend to become quiet and passive when gripped there. This behavior also extends into adulthood, when a male will grab the female by the scruff to immobilize her while he mounts, and to prevent her from running away as the mating process takes place. This technique can be useful when attempting to treat or move an uncooperative cat. However, since an adult cat is heavier than a kitten, a pet cat should never be carried by the scruff, but should instead have its weight supported at the rump and hind legs, and at the chest and front paws. Often (much like a small child) a cat will lie with its head and front paws over a person's shoulder, and its back legs and rump supported under the person's arm. Senses. Cat senses are attuned for hunting. Cats have highly advanced hearing, eyesight, taste, and touch receptors, making the cat extremely sensitive among mammals. Cats' night vision is superior to humans although their vision in daylight is inferior. Cat eyes have a tapetum lucidum and cat eyes that are blue typically lack melanin and hence can show the red-eye effect (see odd-eyed cat). Humans and cats have a similar range of hearing on the low end of the scale, but cats can hear much higher-pitched sounds, up to 64 kHz, which is 1.6 octaves above the range of a human, and even one octave above the range of a dog. A domestic cat's sense of smell is about fourteen times as strong as a human's. Due to a mutation in an early cat ancestor, one of two genes necessary to taste sweetness may have been lost by the cat family. To aid with navigation and sensation, cats have dozens of movable vibrissae (whiskers) over their body, especially their face. Metabolism. Cats conserve energy by sleeping more than most animals, especially as they grow older. The daily duration of sleep varies, usually 12–16 hours, with 13–14 being the average. Some cats can sleep as much as 20 hours in a 24-hour period. The term "cat nap" refers to the cat's ability to fall asleep (lightly) for a brief period and has entered the English lexicon – someone who nods off for a few minutes is said to be "taking a cat nap". Due to their crepuscular nature, cats are often known to enter a period of increased activity and playfulness during the evening and early morning, dubbed the "evening crazies", "night crazies", "elevenses", or "mad half-hour" by some. The temperament of a cat can vary depending on the breed and socialization. Cats with oriental body types tend to be thinner and more active, while cats that have a cobby body type tend to be heavier and less active. The normal body temperature of a cat is between 38 and 39 °C (101 and 102.2 °F). A cat is considered febrile (hyperthermic) if it has a temperature of 39.5 °C (103 °F) or greater, or hypothermic if less than 37.5 °C (100 °F). For comparison, humans have a normal temperature of approximately 36.8 °C (98.6 °F). A domestic cat's normal heart rate ranges from 140 to 220 beats per minute, and is largely dependent on how excited the cat is. For a cat at rest, the average heart rate usually is between 150 and 180 bpm, about twice that of a human (average 80 bpm). Genetics. A 2007 study published in the journal "Science" asserts that all house cats are descended from a group of self-domesticating desert wildcats "Felis silvestris lybica" circa 10,000 years ago, in the Near East. The domesticated cat and its closest wild ancestor are both diploid organisms that possess 38 chromosomes, in which over 200 heritable genetic defects have been identified, many homologous to human inborn errors. Specific metabolic defects have been identified underlying many of these feline diseases. There are several genes responsible for the hair color identified. The combination of them gives different phenotypes. Features like hair length, lack of tail, or presence of a very short tail (bobtail cat) are also determined by single alleles and modified by polygenes. The Cat Genome Project, sponsored by the Laboratory of Genomic Diversity at the U.S. National Cancer Institute Frederick Cancer Research and Development Center in Frederick, Maryland, focuses on the development of the cat as an animal model for human hereditary disease, infectious disease, genome evolution, comparative research initiatives within the family Felidae, and forensic potential. All felines, including the big cats, have a genetic anomaly that may prevent them from tasting sweetness, which is a likely factor for their indifference to or avoidance of fruits, berries, and other sugary foods. Feeding and diet. Cats feed on small prey such as insects, birds, and rodents. Feral cats, or house cats who are free-fed, consume about 8 to 16 small meals in a single day. Despite this, adult cats can adapt to being fed once a day. Cats are classified as obligate carnivores, because their physiology is geared toward efficient processing of meat, and lacks efficient processes for digesting plant matter. The cat cannot produce its own taurine (an essential organic acid), and, as it is contained in flesh, the cat must eat flesh to survive (see Taurine and cats). Similarly as with its teeth, a cat's digestive tract has become specialized over time to suit meat eating, having shortened in length only to those segments of intestine best able to break down proteins and fats from animal flesh. This trait severely limits the cat's ability to properly digest, metabolize, and absorb plant-derived nutrients, as well as certain fatty acids. For example, taurine is scarce in plants but abundant in meats. It is a key amino sulfonic acid for eye health in cats. Taurine deficiency can cause a condition called macular degeneration wherein the cat's retina slowly degenerates, eventually causing irreversible blindness. Despite the cat's meat-oriented physiology, it is still quite common for a cat to supplement its carnivorous diet with small amounts of grass, leaves, shrubs, houseplants, or other plant matter. One theory suggests this behavior helps cats regurgitate if their digestion is upset; another is that it introduces fiber or trace minerals into the diet. In this context, caution is recommended for cat owners because some houseplants are harmful to cats. For example, the leaves of the Easter Lily can cause permanent and life-threatening kidney damage to cats, and Philodendron are also poisonous to cats. The Cat Fanciers' Association has a full list of plants harmful to cats. There are several vegetarian or vegan commercially available cat foods supplemented with chemically synthesized taurine and other added nutrients that attempt to address nutritional shortfalls. Cats can be selective eaters (which may be due in some way to the aforementioned mutation which caused their species to lose sugar-tasting ability). However, cats generally cannot tolerate lack of food for more than 36 hours without risking liver damage. Cats have a fondness for catnip, which is sensed by their olfactory systems. Many enjoy consuming catnip, and most will often roll in it, paw at it, and occasionally chew on it. Cats also can also develop odd eating habits. Some cats like to eat or chew on other things like plastic, paper, string, wool, or even coal. This condition is called pica and can threaten the cat's health depending on the amount and toxicity of the non-food items eaten. The condition's name comes from the Latin word for magpie, a bird which is reputed to eat almost anything. Toxic sensitivity. The liver of a cat is less effective at detoxification than those of other animals, including humans and dogs; therefore exposure to many common substances considered safe for households may be dangerous to them. In general, the cat's environment should be examined for the presence of such toxins and the problem corrected or alleviated as much as possible; in addition, where sudden or prolonged serious illness without obvious cause is observed, the possibility of toxicity must be considered, and the veterinarian informed of any such substances to which the cat may have had access. For instance, the common painkiller paracetamol or acetaminophen, sold under brand names such as Tylenol and Panadol, is extremely toxic to cats; because they naturally lack enzymes needed to digest it, even minute portions of doses safe for humans can be fatal and any suspected ingestion warrants immediate veterinary attention. Even aspirin, which is sometimes used to treat arthritis in cats, is much more toxic to them than to humans and must be administered cautiously. Similarly, application of minoxidil (Rogaine) to the skin of cats, either accidental or by well-meaning owners attempting to counter loss of fur, has sometimes proved fatal. In addition to such obvious dangers as insecticides and weed killers, other common household substances that should be used with caution in areas where cats may be exposed to them include mothballs and other naphthalene products, as well as phenol based products often used for cleaning and disinfecting near cats' feeding areas or litter boxes, such as Pine-Sol, Dettol (Lysol), hexachlorophene, "etc." which, although they are widely used without problem, have been sometimes seen to be fatal. Ethylene glycol, often used as an automotive antifreeze, is particularly appealing to cats, and as little as a teaspoonful can be fatal. Essential oils are toxic to cats and there have been reported cases of serious illnesses caused by tea tree oil, and tea tree oil-based flea treatments and shampoos. Many human foods are somewhat toxic to cats; theobromine in chocolate can cause theobromine poisoning, for instance, although few cats will eat chocolate. Toxicity in cats ingesting relatively large amounts of onions or garlic has also been reported. Even such seemingly safe items as cat food packaged in pull tab tin cans have been statistically linked to hyperthyroidism; although the connection is far from proven, suspicion has fallen on the use of bisphenol A-based plastics, another phenol based product as discussed above, to seal such cans. Many houseplants are at least somewhat toxic to many species, cats included and the consumption of such plants by cats is to be avoided. Sociability. For cats, life in close proximity with humans (and other animals kept by humans) amounts to a "symbiotic social adaptation" which has developed over thousands of years. It has been suggested that, ethologically, the human keeper of a cat functions as a sort of surrogate for the cat's mother, and that adult domestic cats live their lives in a kind of extended kittenhood, a form of behavioral neoteny. Cats may express affection towards their human companions, especially if they imprint on them at a very young age and are treated with consistent affection. Regardless of the average sociability of any given cat or of cats in general, there are still any number of cats who meet or exceed the negative feline stereotype insofar as being poorly socialized. Older cats have also been reported to sometimes develop aggressiveness towards kittens, which may include biting and scratching; this type of behavior is known as Feline Asocial Aggression. Cohabitation. One may see natural house cat behavior by observing feral domestic cats, which are social enough to form colonies. Each cat in a colony holds a distinct territory, with sexually active males having the largest territories, and neutered cats having the smallest. Between these territories are neutral areas where cats watch and greet one another without territorial conflicts. Outside these neutral areas, territory holders usually aggressively chase away stranger cats, at first by staring, hissing, and growling, and if that does not work, by short but noisy and violent attacks. Despite cohabitation in colonies, cats do not have a social survival strategy, or a pack mentality. This mainly means that an individual cat takes care of all basic needs on its own (e.g., finding food, and defending itself), and thus cats are always lone hunters; they do not hunt in groups as dogs or lions do. Cats frequently tonguebathe themselves (see hygiene). The chemistry of their saliva, expended during their frequent grooming, appears to be a natural deodorant. Thus, a cat's cleanliness would aid in decreasing the chance a prey animal could notice the cat's presence. By contrast, dog odor is an advantage in hunting, for a dog is a pack hunter; part of the pack stations itself upwind, and its odor drives prey towards the rest of the pack stationed downwind. This requires a cooperative effort, which in turn requires communication skills. No such communication skills are required of a lone hunter. Fighting. When engaged in feline-to-feline combat for self-defense, territory, reproduction, or dominance, fighting cats make themselves appear more impressive and threatening by raising their fur and arching their backs, thus increasing their apparent size. Cats also behave this way while playing. Attacks usually comprise powerful slaps to the face and body with the forepaws as well as bites, but serious damage is rare; usually the loser runs away with little more than a few scratches to the face, and perhaps the ears. Cats will also throw themselves to the ground in a defensive posture to rake with their powerful hind legs. Normally, serious negative effects will be limited to possible infections of the scratches and bites, though these have been known to sometimes kill cats if untreated. In addition, such fighting is believed to be the primary route of transmission of feline immunodeficiency virus (FIV). Sexually active males will usually be in many fights during their lives, and often have decidedly battered faces with obvious scars and cuts to the ears and nose. Not only males will fight; females will also fight over territory or to defend their kittens. Play. Domestic cats, especially young kittens, are known for their love of play. This behavior mimics hunting and is important in helping kittens learn to stalk, capture, and kill prey. Many cats cannot resist a dangling piece of string, or a piece of rope drawn randomly and enticingly across the floor. This well known love of string is often depicted in cartoons and photographs, which show kittens or cats playing with balls of yarn. It is probably related to hunting instincts, including the common practice of kittens hunting their mother's and each other's tails. If string is ingested, however, it can become caught in the cat’s stomach or intestines, causing illness, or in extreme cases, death. Due to possible complications caused by ingesting a string, string play is sometimes replaced with a laser pointer's dot, which some cats will chase. While caution is called for, there are no documented cases of feline eye damage from a laser pointer, and the combination of precision needed and low energy involved make it a remote risk. A common compromise is to use the laser pointer to draw the cat to a prepositioned toy so the cat gets a reward at the end of the chase. A regular flashlight with a well-focused light spot has been commonly used in such play for decades, preceding the availability of consumer laser pointers. Cats will also engage in play fighting, with each other and with human partners. Humans "wrestling" with a supine cat, however, should be wary: if the cat is overstimulated or startled it may decide that the play has turned serious and cease to pull its punches; this can lead to serious scratches and occasionally even bites. Hunting. Much like their big cat relatives, domestic and feral cats are very effective predators. Domestic felines ambush or pounce upon and immobilize vertebrate prey using tactics similar to those of leopards and tigers. Having overpowered such prey, a cat delivers a lethal neck bite with its long canine teeth that either severs the prey's spinal cord with irreversible paralysis to prey, causes fatal bleeding by puncturing the carotid artery or the jugular vein, or asphyxiates the prey by crushing its trachea. One poorly understood element of cat hunting behavior is the presentation of prey to human owners. Ethologist Paul Leyhausen proposed that cats adopt humans into their social group, and share excess kill with others in the group according to the local pecking order, in which humans are placed at or near the top. However, anthropologist and animal scientist Desmond Morris in his 1986 book "Catwatching" suggests that when cats bring home mice or birds they have caught, they are teaching their human to hunt, or helping their human as if feeding (his words) "an elderly, inept kitten". Another possibility is that presenting the kill might be a relic of a kitten's behavior of demonstrating for its mother's approval that it has developed the necessary skill for hunting. Indoor cats will often retain their hunting instinct and deliver small household items to their owners, such as watches, pens, pencils, and other objects they can carry in their mouths. Reproduction. Cats are seasonally polyestrous, which means they may have many periods of heat over the course of a year. A heat period lasts about 4 to 7 days if the female is bred; if she is not, the heat period lasts longer. Multiple males will be attracted to a female in heat. The males will fight over her, and the victor wins the right to mate. At first, the female will reject the male, but eventually the female will allow the male to mate. The female will give a loud yowl as the male pulls out of her. After mating, the female will give herself a thorough wash. If a male attempts to breed with her at this point, the female will attack him. Once the female is done grooming, the cycle will repeat. The male cat's penis has spines which point backwards. Upon withdrawal of the penis, the spines rake the walls of the female's vagina, which may cause ovulation. Because this does not always occur, females are rarely impregnated by the first male with which they mate. Furthermore, cats are superfecund; that is, a female may mate with more than one male when she is in heat, meaning different kittens in a litter may have different fathers. The gestation period for cats is approximately 63–65 days. The size of a litter averages three to five kittens, with the first litter usually smaller than subsequent litters. Kittens are weaned at between six and seven weeks, and cats normally reach sexual maturity at 5–10 months (females) and to 5–7 months (males). Cats are ready to go to new homes at about 12 weeks old (the recommended minimum age by Fédération Internationale Féline), or when they are ready to leave their mother. Cats can be surgically sterilized (spayed or castrated) as early as 6–8 weeks to limit unwanted reproduction. This surgery also prevents undesirable sex-related behavior, such as territory marking (spraying urine) in males and yowling (calling) in females. If a cat is neutered after such behavior has been learned, however, then the behavior may persist. Hygiene. Cats are known for their fastidious cleanliness. They groom themselves by licking their fur, employing their hooked papillae and saliva. As mentioned, their saliva is a powerful cleaning agent and deodorant. Many cats also enjoy grooming humans or other cats. Sometimes the act of grooming another cat is initiated as an assertion of superior position in the pecking order of a group (dominance grooming). Some cats occasionally regurgitate hairballs of fur that have collected in their stomachs as a result of their grooming. Longhaired cats are more prone to this than shorthaired cats. Hairballs can be prevented with certain cat foods and remedies that ease elimination of the hair and regular grooming of the coat with a comb or stiff brush. Scratching. Cats are naturally driven to periodically hook their front claws into suitable surfaces and pull backwards, in order to clean the claws and remove the worn outer sheath, as well as exercise and stretch their muscles. This scratching behavior seems enjoyable to the cat, and even declawed cats will go through elaborate scratching routines with every evidence of great satisfaction, despite the total lack of results. Some researchers believe this is due to scent glands located in their pads, and that scratching is effectively a part of marking territory. Fondness for heights. Most breeds of cat have a noted fondness for settling in high places, or perching. Animal behaviorists have posited a number of explanations, the most common being that height gives the cat a better observation point, allowing it to survey its territory and become aware of activities of people and other pets in the area. In the wild, a higher place may serve as a concealed site from which to hunt; domestic cats are known to strike prey by pouncing from such a perch as a tree branch, as does a leopard. Height, therefore, can also give cats a sense of security. During a fall from a high place, a cat can reflexively twist its body and right itself using its acute sense of balance and flexibility. This is known as the cat's "righting reflex". It always rights itself in the same way, provided it has the time to do so, during a fall. The height required for this to occur in most cats (safely) is around 90 cm (3 feet). Cats without a tail also have this ability, since a cat mostly moves its hind legs and relies on conservation of angular momentum to set up for landing, and the tail is in fact little used for this feat. However, cats' fondness for high spaces can dangerously test the righting reflex. The American Society for the Prevention of Cruelty to Animals warns owners to safeguard the more dangerous perches in their homes, to avoid "high-rise syndrome", where an overconfident cat falls from an extreme height. Habitat. The African Wildcat ("Felis silvestris lybica"), ancestor of the domestic cat, is believed to have evolved in a desert climate, as evident in the behavior common to both the domestic and wild forms. Wildcats ("Felis sylvestris") are native to all continents other than Australia and Antarctica, although feral cats have become apex predators in the Australian Outback where they are menaces to wildlife. Their feces are usually dry, and cats prefer to bury them in sandy places. Urine is highly concentrated, which allows the cat to retain as much fluid as possible. They are able to remain motionless for long periods, especially when observing prey and preparing to pounce. In North Africa there are still small wildcats that are probably related closely to the ancestors of today's domesticated cat breeds. Being closely related to desert animals, cats enjoy heat and solar exposure, often sleeping in a sunny area during the heat of the day, as part of a general preference for warm temperatures. Where humans typically start to feel uncomfortable when their skin temperature gets higher than about 44.5 °C (112 °F), by contrast cats do not start to show signs of discomfort until their skin reaches about 52 °C (126 °F). Overall, cats can easily withstand the heat and cold of a temperate climate, so long as the cold is not for extended periods. Although certain breeds such as the Norwegian Forest Cat and Maine Coon have developed heavier coats of fur than other cats, they have little resistance against moist cold (e.g., fog, rain, and snow) and struggle to maintain their 39 °C (102 °F) body temperature when wet. In direct relation to that fact, most cats dislike immersion in water. One major exception is the Turkish Van breed which has an unusual fondness for water. Abyssinians and Bengals are also reported to be more tolerant of water than most cats. Impact of hunting. The domestic cat hunts and eats over a thousand species, many of them invertebrates, especially insects — many big cats will eat fewer than a hundred different species. Although theoretically big cats can kill most of these species as well, they often do not due to the relatively low nutritional content that smaller animals provide for the effort. An exception is the leopard, which commonly hunts rabbits and many other smaller animals. Even well-fed domestic cats may hunt and kill birds, mice, rats, scorpions, cockroaches, grasshoppers, and other small animals in their environment. As a consequence of their exceptional hunting ability, cats can be quite destructive to ecosystems in which they are not native, where local species have not had time to adapt to feline introduction. In some cases, cats have contributed to or caused extinctions — for example, see the case of the Stephens Island Wren. Due to their hunting behavior, in many countries feral cats are considered pests. Domestic cats are occasionally also required to have contained cat runs or to be kept inside entirely, as they can be hazardous to locally endangered bird species. For instance, various municipalities in Australia have enacted such legislation. In some localities, owners fit their cat with a bell in order to warn prey of its approach (although some cats may figure out how and when the bell works, thereby learning more careful movements to avoid the ringing). Domestication. In 2004, a grave was excavated in Cyprus that contained the skeletons, laid close to one another, of both a human and a cat. The grave is estimated to be 9,500 years old, pushing back the earliest known feline-human association significantly. Like some other domesticated animals, cats live in a mutualistic arrangement with humans. It is believed that the benefit of removing rats and mice from humans' food stores outweighed the trouble of extending the protection of a human settlement to a formerly wild animal, almost certainly for humans who had adopted a farming economy. Unlike the dog, which also hunts and kills rodents, the cat does not eat grains, fruits, or vegetables. In modern rural areas, farms often have dozens of semi-feral cats. Hunting in the barns and the fields, they kill and eat rodents that would otherwise spoil large parts of the grain crop. Many pet cats successfully hunt and kill rabbits, rodents, birds, lizards, frogs, fish, and large insects by instinct, but might not eat their prey. In modern urban areas, some people find feral and free-roaming pet cats annoying and intrusive. Unaltered cats can engage in persistent nighttime calling (termed caterwauling) and defecation or "marking" of private property. Indoor confinement of pets and TNR programs for feral cats can help; some people also use cat deterrents to discourage cats from entering their property. In captivity, indoor cats typically live 14 to 20 years, though the oldest known cat lived to age 36. Domesticated cats tend to live longer if they are not permitted to go outdoors (reducing the risk of injury from fights or accidents and exposure to diseases) and if they are neutered. Some such benefits are: castrated male cats cannot develop testicular cancer, spayed female cats cannot develop ovarian cancer, and both have a reduced risk of mammary cancer. Interaction with humans. Human attitudes toward cats vary widely. Some people keep cats for casual companionship as pets. Cats are also bred and shown as registered pedigree pets, in a hobby known as the cat fancy. Because of their small size, domesticated house cats pose almost no major danger to adult humans — the main hazard is the possibility of infection (e.g., cat scratch disease, or, rarely, rabies) from a cat bite or scratch. Cats can also potentially inflict severe scratches or puncture an eye, though this is quite rare (although dogs have been known to be blinded by cats in fights, where the cat specifically and accurately targeted the eyes of the larger animal). Allergens. Allergic reactions to cat dander and or cat saliva inspire one of the most common reasons people cite for disliking cats. Some humans who are allergic to cats—typically manifested by hay fever, asthma, or a skin rash—quickly acclimate themselves to a particular animal and live comfortably in the same house with it, while retaining an allergy to cats in general. However, this should not be depended upon. Many humans find the rewards of cat companionship outweigh the discomfort and problems associated with these allergens. Some cope with the problem by taking prescription allergy medicine, along with bathing their cats frequently (weekly bathing will eliminate about 90% of the cat dander present in the environment). There are also attempts to breed cats that are less likely to provoke an allergic reaction. Trainability. Some owners seek to train their cat in performing tricks commonly exhibited by dogs, such as jumping, though this is rare. Individual cats have been known to learn to manipulate simple mechanisms, like sink faucets, by themselves or after prompting encouraging. With effort and patience on the part of an owner, the average cat can usually be trained to at least obey simple commands such as "get off the furniture" or "come to dinner". In general though, the seeming intractability of the ordinary house cat to training has long inspired the simile 'like herding cats', as a general expression to describe any situation with a stubborn or uncooperative learner. Indoor scratching. Cats are naturally driven to periodically hook their front claws into suitable surfaces and pull backwards, in order to clean the claws. Indoor cats benefit from being provided with a scratching post so that they are less likely to use carpet or furniture which they can easily ruin. Commercial scratching posts typically are covered in carpeting or upholstery, but some authorities advise against this practice, as not making it clear to the cat which surfaces are permissible and which are not; they suggest using a plain wooden surface, or reversing the carpeting on the posts so that the rougher texture of the carpet backing is a more attractive alternative to the cat than the floor covering. Scratching posts made of sisal rope or corrugated cardboard are also commonly found. Some indoor cats, however, especially those that were taken as kittens from feral colonies, may not understand the concept of a scratching post, and as a result will ignore it. Although scratching can serve cats to keep their claws from growing excessively long, their nails can be trimmed if necessary with a small nail trimmer designed for humans, or a small pair of electrician's diagonal cutting pliers, or a guillotine type cutter specifically designed for animal nail trimming. Care must always be taken to avoid cutting the quick of the claw, analogous to cutting into the tip of a finger and equally painful and bloody. The position of the quick can be easily seen through the translucent nail of a cat with light colored claws but not in cats with dark colored nails, who therefore require carefully trimming of only small amounts from the nails. Scratching can be reduced and even eliminated by disciplining the cat with a quick spritz from a water bottle when the cat is scratching or by applying a product called Sticky Paws (similar to double-sided tape) to the surface the cat is prone to scratch. Cats are also repelled by citrus scents, and a citrus-scented product may also help stop unwanted furniture destruction. Pet supply stores also sell bitter apple spray, which cats do not like and will generally avoid. Declawing. Declawing is a surgical procedure, known as "onychectomy", to remove the claw and first bone of each digit of a cat's paws. Declawing is most commonly only performed on front feet. Declawing may be performed to prevent the cat from damaging furniture. Additionally, declawing may be performed on vicious cats, cats that frequently fight with other pets, or cats that are too efficient at predation of animals. In the United States, landlords sometimes require that tenants' cats be declawed. Declawing is controversial and is uncommon outside of North America. In many countries, it is prohibited by animal cruelty laws. In the US it is condemned by both the Humane Society of the United States and the American Society for the Prevention of Cruelty to Animals and many veterinarians refuse to perform the procedure. Waste. Indoor cats are usually provided with a litter box containing litter, typically bentonite, but sometimes other absorbent material such as shredded paper or wood chips, or sometimes sand or similar material. This arrangement serves the same purpose as a toilet for humans. It should be cleaned daily and changed often, depending on the number of cats in a household and the type of litter; if it is not kept clean, a cat may be fastidious enough to find other locations in the house for urination or defecation. This may also happen for other reasons; for instance, if a cat becomes constipated and defecation is uncomfortable, it may associate the discomfort with the litter box and avoid it in favor of another location. A litterbox is recommended for indoor-outdoor cats as well. Daily attention to the litter box also serves as a monitor of the cat's health. Numerous variations on litter and litter box design exist, including some which automatically sift the litter after each use. Bentonite or clumping litter is a variation which absorbs urine into clumps which can be sifted out along with feces, and thus stays cleaner longer with regular sifting, but has sometimes been reported to cause health problems in some cats. Those with toxoplasmosis-infected cats living in habitat areas of sea otters may wish to dispose of droppings in the trash, rather than flushing them down the toilet. Litterboxes may pose a risk of toxoplasmosis transmission to susceptible pregnant women and immuno-compromised individuals. Most indoor-only cats are not normally exposed to the disease and are not carriers. Transmission risk may be reduced by daily litterbox cleaning by someone other than the susceptible individual. Some cats can be trained to use the human toilet, eliminating the litter box and its attendant expense, unpleasant odor, and the need to use landfill space for disposal. Training may involve four to six weeks of incremental moves, such as moving and elevating the litter box until it is near the toilet, as well as employing an adapter such as a bowl or small box to suspend the litter above the toilet bowl. Several kits and other aids are marketed to help toilet-train cats. When training is complete, the cat uses the toilet by squatting on the toilet seat over the bowl. Domesticated varieties. The list of cat breeds is quite large: most cat registries actually recognize between 30 and 40 breeds of cats, and several more are in development, with one or more new breeds being recognized each year on average, having distinct features and heritage. The owners and breeders of show cats compete to see whose animal bears the closest resemblance to the "ideal" definition & standard of the breed (see selective breeding). Because of common crossbreeding in populated areas, many cats are simply identified as belonging to the homogeneous breeds of domestic longhair and domestic shorthair, depending on their type of fur. In the United Kingdom and Australia, non-purebred cats are referred in slang as moggies (derived from "Maggie", short for Margaret, reputed to have been a common name for cows and calves in 18th century England and latter applied to housecats during the Victorian era). In the United States, a non-purebred cat is sometimes referred to in slang as a barn or alley cat, even if it is not a stray. Cats come in a variety of colors and patterns. These are physical properties and should not be confused with a breed of cat. Some original cat breeds that have a distinct phenotype that is the main type occurring naturally as the dominant domesticated cat type in their region of origin are sometimes considered as subspecies and also have received names as such in nomenclature, although this is not supported by feline biologists. Some of these cat breeds are: Coat patterns. Cat coat genetics can produce a variety of coat patterns. Some of the most common are: Body types. Cats can also come in several body types, ranging between two extremes: Feral cats. Feral cats may live alone, but most are found in large groups called feral colonies with communal nurseries, depending on resource availability. Most abandoned cats probably have little alternative to joining a feral colony. Some feral cat colonies are found in large cities such as around the Colosseum and Forum Romanum in Rome. The Roman cats are not truly feral because they are partly fed and vetted by the local authority. Because cats are adaptable, those in residential areas know that if they are friendly to humans they need not worry about food or shelter. Some urban "stray" cats have many houses humans to support them. Although cats are adaptable, feral felines are unable to thrive in extreme cold and heat, and with a very high protein requirement, few find adequate nutrition on their own in cities. They are often killed by dogs, coyotes, and automobiles. However, there are thousands of volunteers and organizations that trap these unadoptable feral felines, neutering them, immunize the cats against rabies and feline leukemia, and treat them with long-lasting flea products. Before release back into their feral colonies, the attending veterinarian often nips the tip off one ear to mark the feral as neutered and inoculated, since these cats will more than likely find themselves trapped again. Volunteers continue to feed and give care to these cats throughout their lives, and not only is their lifespan greatly increased, but behavior and nuisance problems, due to competition for food, are also greatly reduced. Environmental effects. Feral cats are thought to be a major predator of Hawaiian coastal and forest habitats, and are one species among many responsible for the decline of endemic forest bird species as well as seabirds like the Wedge-tailed Shearwater. In one study of 56 cats' feces, the remains of 44 birds were found, 40 of which were endemic species. In the Southern Hemisphere there are many landmasses including Australia where cat species have never been native, and other placental mammalian predators were rare or absent. Native species there, for example, the Kakapo, tend to be more ecologically vulnerable and behaviorally "naive" to predation by feral cats. Feral cats have had serious effects on these wildlife species and have played a leading role in the endangerment and extinction of many of them. In Australia a large quantity of native birds, lizards and small marsupials are taken every year by feral cats, and feral cats have played a role in driving some small marsupial species to extinction. Some organizations in Australia are now going to effort of creating fenced islands of habitat for endangered species that are free of feral cats and foxes. Ethical and humane concerns over feral cats. The environmental impact of feral cat programs and of indoor outdoor cats is a subject of debate. Part of this stems from humane concern for the cats, and part stems from concerns about cat predation on endangered species. The amount of ecological damage done by indoor outdoor cats depends on local conditions. As suggested above, the most severe effect occurs to island ecologies. Environmental concerns may be minimal in most of the UK where cats are an established species and few to none of the local prey species are endangered. Pet owners can contact veterinarians, ecological organizations, and universities for opinions about whether local conditions are suitable for outdoor cats. Additional concerns include potential dangers from larger predators and infectious diseases. Coyotes kill large numbers of housecats in the Southwestern United States, even in urban zones. FELV (feline leukemia), FIV (feline immunodeficiency virus), or rabies may be present in the area. If faced with conflicting evidence, the safe choice is to keep a cat indoors. Cats present a risk of overpopulation, as well. According to the Humane Society of the United States, 3–4 million cats and dogs are euthanized each	The horse'" ("Equus ferus caballus") is a hoofed (ungulate) mammal, a subspecies of one of seven extant species of the family Equidae. The horse has evolved over the past 45 to 55 million years from a small multi-toed creature into the large, single-toed animal of today. Humans began to domesticate horses around 4000 BC, and their domestication is believed to have been widespread by 3000 BC; by 2000 BC the use of domesticated horses had spread throughout the Eurasian continent. Although most horses today are domesticated, there are still endangered populations of the Przewalski's Horse, the only remaining true wild horse, as well as more common feral horses which live in the wild but are descended from domesticated ancestors. There is an extensive, specialized vocabulary used to describe equine-related concepts, covering everything from anatomy to life stages, size, colors, markings, breeds, locomotion, and behavior. Horses are anatomically designed to use speed to escape predators, and have a well-developed sense of balance and a strong fight-or-flight instinct. Related to this need to flee from predators in the wild is an unusual trait: horses are able to sleep both standing up and lying down. Female horses, called mares, carry their young for approximately 11 months, and a young horse, called a foal, can stand and run shortly following birth. Most domesticated horses begin training under saddle or in harness between the ages of two and four. They reach full adult development by age five, and have an average lifespan of between 25 and 30 years. Horse breeds are loosely divided into three categories based on general temperament: spirited "hot bloods" with speed and endurance; "cold bloods," such as draft horses and some ponies, suitable for slow, heavy work; and "warmbloods," developed from crosses between hot bloods and cold bloods, often focusing on creating breeds for specific riding purposes, particularly in Europe. There are over 300 breeds of horses in the world today, developed for many different uses. Horses and humans interact in many ways, not only in a wide variety of sport competitions and non-competitive recreational pursuits, but also in working activities including police work, agriculture, entertainment, assisted learning and therapy. Horses were historically used in warfare. A wide variety of riding and driving techniques have been developed, using many different styles of equipment and methods of control. Many products are derived from horses, including meat, milk, hide, hair, bone, and pharmaceuticals extracted from the urine of pregnant mares. Humans provide domesticated horses with food, water and shelter, as well as attention from specialists such as veterinarians and farriers. Biology. Horse anatomy is described by a large number of specific terms, as illustrated by the chart to the right. Specific terms also describe various ages, colors and breeds. Age. Depending on breed, management and environment, the domestic horse today has a life expectancy of 25 to 30 years. It is uncommon, but a few animals live into their 40s and, occasionally, beyond. The oldest verifiable record was "Old Billy," a 19th-century horse that lived to the age of 62. In modern times, Sugar Puff, who had been listed in the Guinness Book of World Records as the world's oldest living pony, died in 2007, aged 56. Regardless of a horse's actual birth date, for most competition purposes an animal is considered a year older on January 1 of each year in the northern hemisphere and August 1 in the southern hemisphere. The exception is in endurance riding, where the minimum age to compete is based on the animal's calendar age. A very rough estimate of a horse's age can be made from looking at its teeth. The following terminology is used to describe horses of various ages: In horse racing, the definitions of colt, filly, mare, and stallion may differ from those given above. In the UK, Thoroughbred horse racing defines a colt as a male less than five years old, and a filly as a female less than five years old. In the USA, both Thoroughbred racing and harness racing defines colts and fillies as four years old and younger. Size. The English-speaking world measures the height of horses in hands, abbreviated "h" or "hh," for "hands high," measured at the highest point of an animal's withers, where the neck meets the back, chosen as a stable point of the anatomy, unlike the head or neck, which move up and down; one hand is. Intermediate heights are defined by hands and inches, rounding to the lower measurement in hands, followed by a decimal point and the number of additional inches between 1 and 3. Thus a horse described as "15.2 h," is 15 hands, 2 inches in height. The size of horses varies by breed, but can also be influenced by nutrition. The general rule for cutoff in height between what is considered a horse and a pony at maturity is 14.2 hands. An animal 14.2 h or over is usually considered to be a horse and one less than 14.2 h a pony. However, there are exceptions to the general rule. Some breeds which typically produce individuals both under and over 14.2 h are considered horses regardless of their height. Conversely, some pony breeds may have features in common with horses, and individual animals may occasionally mature at over 14.2 h, but are still considered to be ponies. The distinction between a horse and pony is not simply a difference in height, but takes account of other aspects of "phenotype" or appearance, such as conformation and temperament. Ponies often exhibit thicker manes, tails and overall coat. They also have proportionally shorter legs, wider barrels, heavier bone, shorter and thicker necks, and short heads with broad foreheads. They often have calmer temperaments than horses and also a high level of equine intelligence that may or may not be used to cooperate with human handlers. In fact, small size, by itself, is sometimes not a factor at all. While the Shetland pony stands on average 10 hands high, the Falabella and other miniature horses, which can be no taller than, the size of a medium-sized dog, are classified by their respective registries as very small horses rather than as ponies. Light riding horses such as Arabians, Morgans, or Quarter Horses usually range in height from 14 to 16 hands and can weigh from. Larger riding horses such as Thoroughbreds, American Saddlebreds or Warmbloods usually start at about 15.2 hands and often are as tall as 17 hands, weighing from. Heavy or draft horses such as the Clydesdale, Belgian, Percheron, and Shire are usually at least 16 to 18 hands high and can weigh from about. The largest horse in recorded history was probably a Shire horse named Sampson, who lived during the late 1800s. He stood 21.2½ hands high, and his peak weight was estimated at. The current record holder for the world's smallest horse is Thumbelina, a fully mature miniature horse affected by dwarfism. She is tall and weighs. Colors and markings. Horses exhibit a diverse array of coat colors and distinctive markings, described with a specialized vocabulary. Often, a horse is classified first by its coat color, before breed or sex. Flashy or unusual colors are sometimes very popular, as are horses with particularly attractive markings. Horses of the same color may be distinguished from one another by their markings. The genetics that create many horse coat colors have been identified, although research continues on specific genes and mutations that result in specific color traits. Essentially, all horse colors begin with a genetic base of "red" (chestnut) or "black," with the addition of alleles for spotting, graying, suppression or dilution of color, or other effects acting upon the base colors to create the dozens of possible coat colors found in horses. Horses which are light in color are often misnamed as being "white" horses. A horse that looks pure white is, in most cases, actually a middle-aged or older gray. Grays have black skin underneath their white hair coat (with the exception of small amounts of pink skin under white markings). The only horses properly called white are those with pink skin under a white hair coat, a fairly rare occurrence. There are no truly albino horses, with pink skin and red eyes, as albinism is a lethal condition in horses. Reproduction and development. Pregnancy lasts for approximately 335–340 days and usually results in one foal. Twins are very rare. Colts are carried on average about 4 days longer than fillies. Horses are a precocial species, and foals are capable of standing and running within a short time following birth. Horses, particularly colts, may sometimes be physically capable of reproduction at about 18 months. In practice, individuals are rarely allowed to breed before the age of three, especially females. Horses four years old are considered mature, although the skeleton normally continues to develop until the age of six; the precise time of completion of development also depends on the horse's size, breed, gender, and the quality of care provided by its owner. Also, if the horse is larger, its bones are larger; therefore, not only do the bones take longer to actually form bone tissue, but the epiphyseal plates are also larger and take longer to convert from cartilage to bone. These plates convert after the other parts of the bones, but are crucial to development. Depending on maturity, breed, and the tasks expected, young horses are usually put under saddle and trained to be ridden between the ages of two and four. Although Thoroughbred race horses are put on the track at as young as two years old in some countries, horses specifically bred for sports such as dressage are generally not entered into top-level competition until they are a minimum of four years old, because their bones and muscles are not solidly developed, nor is their advanced training complete. For endurance riding competition, horses are not deemed mature enough to compete until they are a full 60 calendar months (5 years) old. Skeletal system. Horses have a skeleton that averages 205 bones. A significant difference between the horse skeleton, compared to that of a human, is the lack of a collarbone—the horse's front limb system is attached to the spinal column by a powerful set of muscles, tendons and ligaments that attach the shoulder blade to the torso. The horse's legs and hooves are also unique structures. Their leg bones are proportioned differently from those of a human. For example, the body part that is called a horse's "knee" is actually made up of the carpal bones that correspond to the human wrist. Similarly, the hock, contains the bones equivalent to those in the human ankle and heel. The lower leg bones of a horse correspond to the bones of the human hand or foot, and the fetlock (incorrectly called the "ankle") is actually the proximal sesamoid bones between the cannon bones (a single equivalent to the human metacarpal or metatarsal bones) and the proximal phalanges, located where one finds the "knuckles" of a human. A horse also has no muscles in its legs below the knees and hocks, only skin, hair, bone, tendons, ligaments, cartilage, and the assorted specialized tissues that make up the hoof. Hooves. The critical importance of the feet and legs is summed up by the traditional adage, "no foot, no horse". The horse hoof begins with the distal phalanges, the equivalent of the human fingertip or tip of the toe, surrounded by cartilage and other specialized, blood-rich soft tissues such as the laminae. The exterior hoof wall and horn of the sole is made of essentially the same material as a human fingernail. The end result is that a horse, weighing on average, travels on the same bones as a human on tiptoe. For the protection of the hoof under certain conditions, some horses have horseshoes placed on their feet by a professional farrier. The hoof continually grows, and needs to be trimmed (and horseshoes reset, if used) every five to eight weeks. Teeth. Horses are adapted to grazing. In an adult horse, there are 12 incisors, adapted to biting off the grass or other vegetation, at the front of the mouth. There are 24 teeth adapted for chewing, the premolars and molars, at the back of the mouth. Stallions and geldings have four additional teeth just behind the incisors, a type of canine teeth that are called "tushes." Some horses, both male and female, will also develop one to four very small vestigial teeth in front of the molars, known as "wolf" teeth, which are generally removed because they can interfere with the bit. There is an empty interdental space between the incisors and the molars where the bit rests directly on the bars (gums) of the horse's mouth when the horse is bridled. The incisors show a distinct wear and growth pattern as the horse ages, as well as change in the angle at which the chewing surfaces meet. The teeth continue to erupt throughout life as they are worn down by grazing, so a very rough estimate of a horse's age can be made by an examination of its teeth, although diet and veterinary care can affect the rate of tooth wear. Digestion. Horses are herbivores with a digestive system adapted to a forage diet of grasses and other plant material, consumed steadily throughout the day. Therefore, compared to humans, they have a relatively small stomach but very long intestines to facilitate a steady flow of nutrients. A horse will eat of food per day and, under normal use, drink to of water. Horses are not ruminants, so they have only one stomach, like humans, but unlike humans, they can also digest cellulose from grasses due to the presence of a "hind gut" called the cecum, or "water gut," which food goes through before reaching the large intestine. Unlike humans, horses cannot vomit, so digestion problems can quickly cause colic, a leading cause of death. Senses. The horse's senses are generally superior to those of a human. As prey animals, they must be aware of their surroundings at all times. They have the largest eyes of any land mammal, and because their eyes are positioned on the sides of their heads, horses have a range of vision of more than 350°, with approximately 65° of this being binocular (seen with both eyes) and the remaining 285° monocular (seen with only one eye). Horses have excellent day and night vision, but studies indicate that they have two-color, or dichromatic vision; their color vision is somewhat like red-green color blindness in humans. This means that certain colors, especially red and related colors, appear more green. Their hearing is good, and the pinna of each ear can rotate up to 180°, giving the potential for 360° hearing without having to move the head. Their sense of smell, while much better than that of humans, is not their strongest asset; they rely to a greater extent on vision. Horses have a great sense of balance, due partly to their ability to feel their footing and partly to highly developed proprioceptive abilities (the unconscious sense of where the body and limbs are at all times). A horse's sense of touch is well developed. The most sensitive areas are around the eyes, ears and nose. Via touch, horses perceive and respond immediately to changes in their environment, sensing contact as subtle as an insect landing anywhere on the body. Horses have an advanced sense of taste that allows them to sort through grains and grasses to choose what they would most like to eat, and their prehensile lips can easily sort even the smallest grains. Horses generally will not eat poisonous plants. However, there are exceptions and horses will occasionally eat toxic amounts of poisonous plants even when there is adequate healthy food. Movement. All horses move naturally with four basic gaits: the four-beat walk, which averages four miles per hour; the two-beat trot or jog, which averages per hour (faster for harness racing horses); and the leaping gaits known as the canter or lope (a three-beat gait that is per hour), and the gallop. The gallop averages per hour. The world record for a horse galloping over a short, sprint distance is per hour. Besides these basic gaits, some horses perform a two-beat pace, instead of the trot. In addition, there are several four-beat "ambling" gaits that are approximately the speed of a trot or pace, though smoother to ride. These include the lateral slow gait, rack, running walk, and tölt as well as the diagonal fox trot. Ambling gaits are often genetic traits in specific breeds, known collectively as gaited horses. In most cases, gaited horses replace the standard trot with one of the ambling gaits. Behavior. Horses are prey animals with a well-developed fight-or-flight instinct. Their first response to threat is to startle and usually flee, although they are known to stand their ground and defend themselves or their offspring in cases where flight is not possible, or when their young are threatened. They also tend to be curious; when startled, they will often hesitate an instant to ascertain the cause of their fright, and may not always flee from something that they perceive as non-threatening. Through selective breeding, some breeds of horses are quite docile, particularly certain large draft horses. Most light horse riding breeds were developed for speed, agility, alertness and endurance; natural qualities that extend from their wild ancestors. Horses are herd animals, with a clear hierarchy of rank, led by a dominant animal (usually a mare). They are also social creatures who are able to form companionship attachments to their own species and to other animals, including humans. They communicate in various ways, including vocalizations such as nickering or whinnying, mutual grooming, and body language. Many horses will become difficult to manage if they are isolated. Through proper training, it is possible to teach any horse to accept a human as a type of companion, and thus be comfortable away from other horses. When confined with insufficient companionship, exercise or stimulation, individuals may develop stable vices, an assortment of bad habits, mostly psychological in origin, that include wood chewing, wall kicking, "weaving" (rocking back and forth) and other problems. Intelligence and learning. In the past, horses were considered unintelligent, with no abstract thinking ability, unable to generalize, and driven primarily by a herd mentality. However, recent studies show that they perform a number of cognitive tasks on a daily basis, and frequently engage in mental challenges that include food procurement and social system identification. They have also been shown to have good spatial discrimination abilities. Studies have assessed equine intelligence in the realms of problem solving, learning speed, and knowledge retention. Results show that horses excel at simple learning, but also are able to solve advanced cognitive challenges that involve categorization and concept learning. They have been shown to learn from habituation, desensitization, Pavlovian conditioning, and operant conditioning. They respond to and learn from both positive and negative reinforcement. Domesticated horses tend to face greater mental challenges than wild horses, due to living in artificial environments that stifle instinctual behavior while learning tasks that are not natural. Horses are creatures of habit that respond and adapt well to regimentation, and respond best when the same routines and techniques are used consistently. Some trainers believe that "intelligent" horses are reflections of intelligent trainers who effectively use response conditioning techniques and positive reinforcement to train in the style that fits best with an individual animal's natural inclinations. Others who handle horses regularly note that personality also may play a role separate from intelligence in determining how a given animal responds to various experiences. Temperament. Thoroughbred race horses are a "hot blooded" breed. Horses are mammals, and as such are "warm-blooded" creatures, as opposed to reptiles, which are cold-blooded. However, these words have developed a separate meaning in the context of equine terminology, used to describe temperament, not body temperature. For example, the "hot-bloods," such as many race horses, exhibit more sensitivity and energy, while the "cold-bloods," such as most draft breeds, are quieter and calmer. "Hot blooded" breeds include "oriental horses" such as the Akhal-Teke, Barb, Arabian horse and now-extinct Turkoman horse, as well as the Thoroughbred, a breed developed in England from the older oriental breeds. Hot bloods tend to be spirited, bold, and learn quickly. They are bred for agility and speed. They tend to be physically refined—thin-skinned, slim, and long-legged. The original oriental breeds were brought to Europe from the Middle East and North Africa when European breeders wished to infuse these traits into racing and light cavalry horses. The "cold blooded" draft breeds are powerful and heavily-muscled Muscular, heavy draft horses are known as "cold bloods," as they are bred not only for strength, but also to have the calm, patient temperament needed to pull a plow or a heavy carriage full of people. They are sometimes nicknamed "gentle giants." Well-known draft breeds include the Belgian and the Clydesdale. Some, like the Percheron are lighter and livelier, developed to pull carriages or to plow large fields in drier climates. Others, such as the Shire, are slower and more powerful, bred to plow fields with heavy, clay-based soils. The cold-blooded group also includes some pony breeds. "Warmblood" breeds, such as the Trakehner or Hanoverian, developed when European carriage and war horses were crossed with Arabians or Thoroughbreds, producing a riding horse with more refinement than a draft horse, but greater size and more phlegmatic temperament than a lighter breed. Certain pony breeds with warmblood characteristics have been developed for smaller riders. A modern "Warmblood" horse is large, but agile and athletic. Today, the term "Warmblood" refers to a specific subset of sport horse breeds that have dominated the Olympic Games and international FEI competition in dressage and show jumping since the 1970s. Prior to that time, the term "warm blood" often referred to any cross between cold-blooded and hot-blooded breeds. Examples included breeds such as the Irish Draught or the Cleveland Bay. Less often, the term was even used to refer to breeds of light riding horse other than Thoroughbreds or Arabians, such as the Morgan horse. Sleep patterns. Horses are able to sleep both standing up and lying down. In an adaptation from life in the wild, horses are able to enter light sleep by using a "stay apparatus" in their legs, allowing them to doze without collapsing. Horses sleep better when in groups because some animals will sleep while others stand guard to watch for predators. A horse kept alone will not sleep well because its instincts are to keep a constant eye out for danger. Unlike humans, horses do not sleep in a solid, unbroken period of time, but take many short periods of rest. Horses may spend anywhere from four to fifteen hours a day in standing rest, and from a few minutes to several hours lying down. Total sleep time in a day may range from several minutes to a couple of hours, mostly in short intervals of about 15 minutes each. Horses must lie down to reach REM sleep. They only have to lie down for an hour or two every few days to meet their minimum REM sleep requirements. However, if a horse is never allowed to lie down, after several days it will become sleep-deprived, and in rare cases may suddenly collapse as it involuntarily slips into REM sleep while still standing. This condition differs from narcolepsy, although horses may also suffer from that disorder. Taxonomy and evolution. The horse as it is known today adapted by evolution to survive in areas of wide-open terrain with sparse vegetation, surviving in an ecosystem where other large grazing animals, especially ruminants, could not. Horses and other equids are odd-toed ungulates of the order Perissodactyla, a group of mammals that was dominant during the Tertiary period. In the past, this order contained 14 families and many species, but only three families—Equidae (the horse and related species), the tapir and the rhinoceros—containing 18 known species have survived to the present day. The earliest known member of the Equidae family was the "Hyracotherium", which lived between 45 and 55 million years ago, during the Eocene period and had 4 toes on each front foot, and 3 toes on each back foot. The extra toe on the front feet soon disappeared with the "Mesohippus", which lived 32 to 37 million years ago, and by about 5 million years ago, the modern Equus had developed. The extra side toes shrank in size until they have vanished in modern horses. All that remains is a set of small vestigial bones on the leg above the hoof, known informally as ergots, chestnuts, or splint bones. Their legs also lengthened as their toes disappeared and until they were a hoofed animal capable of running at great speed. Over millions of years, equid teeth also evolved from browsing on soft, tropical plants to adapt to browsing of drier plant material, and grazing of tougher plains grasses. Thus the proto-horses changed from leaf-eating forest-dwellers to grass-eating inhabitants of semi-arid regions worldwide, including the steppes of Eurasia and the Great Plains of North America. For reasons not fully understood, "Equus caballus" disappeared from North America around 10,000 years ago, at the end of the last ice age. The "Four Foundations" theory. Modern DNA evidence suggests that domesticated horses evolved from multiple wild populations. Specifically, the "Four Foundations" theory suggests that the modern horse evolved from multiple ancient wild prototypes, each adapted to a given habitat. However, an older theory holds that there was only one type of wild horse, the Tarpan subtype, and all other types diverged in form after domestication to meet human needs. Under the four foundations theory, all types and breeds of horses are thought to have developed from the following base prototypes: Domestication and surviving wild species. Competing theories exist as to the time and place of initial domestication. The earliest evidence for the domestication of the horse comes from Ukraine and dates to approximately 4,000 BC. It is thought that the horse was completely domesticated by 3000 BC, and by 2000 BC there was a sharp increase in the number of horse bones found in human settlements in northwestern Europe, indicating the spread of domesticated horses throughout the continent. Wild species surviving into modern times. A truly wild horse is a species or subspecies which has no ancestors that were ever domesticated. Therefore, most "wild" horses today are actually feral horses, animals that escaped or were turned loose from domestic herds and the descendants of those animals. Only two types of truly wild horses survived into recorded history. One, the Tarpan ("Equus ferus ferus") survived into the historical era, but became extinct in 1887. Its pure genetic line was lost, but three attempts have been made to re-create the Tarpan. In the early 1930s, Berlin Zoo Director Lutz Heck and Heinz Heck of the Munich Zoo began a program that by the 1960s produced the Heck horse. In 1936, Polish university professor Tadeusz Vetulani began a program using Konik horses, and in the mid-1960s Harry Hegard started a program in the United States using feral mustangs and local working ranch horses that has resulted in the Hegardt or Stroebel's Horse. None of the breeding programs were completely successful, although all three resulted in horses with many similarities to the Tarpan. There is only one true wild horse species alive today, the Przewalski's Horse ("Equus ferus przewalskii"). It is a rare Asian animal, also known as the Mongolian Wild Horse; Mongolian people know it as the "taki", and the Kyrgyz people call it a "kirtag". Small wild breeding populations of this animal, named after the Russian explorer Nikolai Przhevalsky, exist in Mongolia. There are also small populations maintained at zoos throughout the world. The species was considered extinct in the wild between 1969 and 1992, but a small breeding population was reestablished in the wild due to the conservation efforts of numerous zoos. Feral populations. Feral horses are born and live in the wild, but are descended from domesticated animals. Many populations of feral horses exist throughout the world. Studies of feral herds have provided useful insights into the behavior of prehistoric horses, as well as greater understanding of the instincts and behaviors that drive horses that live in domesticated conditions. Other modern equids. Besides the horse, there are seven other species of genus "equus" in the equidae family. These are the ass or donkey, "Equus asinus"; the Mountain Zebra, "Equus zebra"; Plains Zebra, "Equus burchelli"; Grévy's Zebra, "Equus grevyi"; the Kiang, "Equus kiang"; and the Kulan, "Equus hemionus", including its subspecies, the Onager, "Equus hemionus onager". Horses can crossbreed with other members of the "equus" genus. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, a hinny, is a cross between a stallion and a jenny (female donkey). Other hybrids include the zorse, a cross between a zebra and a horse that is bred in Africa and used for trekking on Mount Kenya. With rare exceptions, most hybrids are sterile and cannot reproduce. Breeds. Horse breeds are groups of horses with distinctive characteristics that are transmitted consistently to their offspring, such as conformation, color, performance ability, or disposition. These inherited traits are usually the result of a combination of natural crosses and artificial selection methods aimed at producing horses for specific tasks. Certain breeds are known for certain talents. For example, Standardbreds are known for their speed in harness racing. Some breeds have been developed through centuries of crossings with other breeds, while others, such as Tennessee Walking Horses and Morgans, developed from a single sire from which all current breed members descend. There are more than 300 horse breeds in the world today. Origin of breeds. Modern horse breeds developed in response to a need for "form to function", the necessity to develop certain physical characteristics in order to perform a certain type of work. Thus, powerful but refined breeds such as the Andalusian or the Lusitano developed in the Iberian peninsula as riding horses that also had a great aptitude for dressage, while heavy draft horses such as the Clydesdale and the Shire developed out of a need to perform demanding farm work and pull heavy wagons. Ponies of all breeds originally developed mainly from the need for a working animal that could fulfill specific local draft and transportation needs while surviving in harsh environments. However, by the 20th century, many pony breeds had Arabian and other blood added to make a more refined pony suitable for riding. Other horse breeds developed specifically for light agricultural work, heavy and light carriage and road work, various equestrian disciplines, or simply as pets. Purebreds and registries. Horses have been selectively bred since their domestication. Today, there are over 300 breeds of horses in the world. However, the concept of purebred bloodstock and a controlled, written breed registry only became of significant importance in modern times. Today, the standards for defining and registration of different breeds vary. Sometimes purebred horses are called Thoroughbreds, which is incorrect; "Thoroughbred" is a specific breed of horse, while a "purebred" is a horse (or any other animal) with a defined pedigree recognized by a breed registry. An early example of people who practiced selective horse breeding were the Bedouin, who had a reputation for careful breeding practices, keeping extensive pedigrees of their Arabian horses and placing great value upon pure bloodlines. Though these pedigrees were originally transmitted via an oral tradition, written pedigrees of Arabian horses can be found that date to the 14th century. In the same period of the early Renaissance, the Carthusian monks of southern Spain bred horses and kept meticulous pedigrees of the best bloodstock; the lineage survives to this day in the Andalusian horse. One of the earliest formal registries was General Stud Book for Thoroughbreds, which began in 1791 and traced back to the Arabian stallions imported to England from the Middle East that became the foundation stallions for the breed. Some breed registries have a closed stud book, where registration is based on pedigree, and no outside animals can gain admittance. For example, a registered Thoroughbred or Arabian must have two registered parents of the same breed. Other breeds have a partially closed stud book but still allow certain infusions from other breeds. For example, the modern Appaloosa must have at least one Appaloosa parent, but may also have a Quarter Horse, Thoroughbred, or Arabian parent so long as the offspring exhibits appropriate color characteristics. The Quarter Horse normally requires both parents to be registered Quarter Horses, but allows "Appendix" registration of horses with one Thoroughbred parent, and the horse may earn its way to full registration by completing certain performance requirements. Others, such as most of the warmblood breeds used in sport horse disciplines, have open stud books to varying degrees. While pedigree is considered, outside bloodlines are admitted to the registry if the horses meet the set standard for the registry. These registries usually require a studbook selection process involving judging of an individual animal's quality, performance, and conformation before registration is finalized. A few "registries," particularly some color breed registries, are very open and will allow membership of all horses that meet limited criteria, such as coat color and species, regardless of pedigree or conformation. Breed registries also differ as to their acceptance or rejection of breeding technology. For example, all Jockey Club Thoroughbred registries require that a registered Thoroughbred be a product of a natural mating, so called "live cover". A foal born of two Thoroughbred parents, but by means of artificial insemination or embryo transfer, cannot be registered in the Thoroughbred studbook. On the other hand, since the advent of DNA testing to verify parentage, most breed registries now allow artificial insemination (AI), embryo transfer (ET), or both. The high value of stallions has helped with the acceptance of these techniques because they allow a stallion to breed more mares with each "collection," and greatly reduce the risk of injury during mating. Cloning of horses is highly controversial, and at the present time most mainstream breed registries will not accept cloned horses, though several cloned horses and mules have been produced. Interaction with humans. Around the world, horses play a role within human cultures. Horses are used for leisure activities, sports, and working purposes. The Food and Agriculture Organization (FAO) reports that in 2003, China had the largest number of horses in the world with over 8 million, followed by Mexico (6,260,000), Brazil (5,900,500), the United States (5,300,000), and Argentina (3,655,000). The American Horse Council estimates that horse-related activities have a direct impact on the economy of the United States of over $39 billion, and when indirect spending is considered, the impact is over $102 billion. In a 2004 "poll" conducted by Animal Planet, more than 50,000 viewers from 73 countries voted for the horse as the world's 4th favorite animal. Sport. Historically, equestrians honed their skills through competitions, games and races. Equestrian sports have the dual purpose of providing entertainment for crowds and creating and preserving the excellent horsemanship that was needed in battle. Many sports, such as dressage, eventing and show jumping, had origins in military training, which were focused on control and balance in both the horse and the rider. Other sports, such as rodeo, developed from practical skills such as those needed on working ranches. Sport hunting from horseback evolved from earlier practical hunting techniques. Horse racing, whether the horse was ridden or driven, evolved out of impromptu competitions between riders or drivers. The evolving competitions, requiring ever more demanding and specialized skills from both horse and rider, resulted in the systematic development of specialized breeds and equipment for each sport. The popularity of equestrian sports through the centuries has resulted in the preservation of skills that would otherwise have rapidly disappeared after horses stopped being used in combat. Horses are trained to be ridden or driven in many different sporting events and competitions. Examples include show jumping, dressage, three-day eventing, competitive driving, endurance riding, gymkhana, rodeos and fox hunting. Horse shows, which have their origins in medieval European fairs, are held around the world as venues in which horses are competed, exhibited and sold. They host a huge range of classes, covering all of the mounted and harness disciplines, as well as "In-hand" classes where the horses are led, rather than ridden, to exhibit their conformation. The method of judging classes varies depending on the discipline, but winning awards usually depends on style and ability of both horse and rider. Sports such as polo do not judge the horse itself, but rather use the horse as a partner for human competitors as a necessary part of the game. Although the horse assists this process and requires specialized training to do so, the details of its performance are not judged, only the result of the rider's actions—be it getting a ball through a goal or some other achievement. Examples of these sports of partnership between human and animal also include jousting (reenacting the skills used by medieval knights), in which the main goal is for one rider to unseat the other, and buzkashi, a team game played throughout Central Asia, the aim being to capture a goat carcass while on horseback. Horse racing is an equestrian sport and also a huge international industry, watched in almost every nation of the world. There are three types: "flat" racing; steeplechasing, i.e. racing over jumps; and harness racing, where horses trot or pace while pulling a driver in a small, light cart known as a sulky. A major part of horse racing's economic importance lies in the gambling associated with it. Communication between human and horse is paramount in any equestrian activity; to aid this process horses are usually ridden with a saddle on their backs to assist the rider with balance and positioning, and a bridle or related headgear to assist the rider in maintaining control. Sometimes horses are ridden without a saddle, and occasionally, horses are trained to perform without a bridle or other headgear. Many horses are also driven, which requires a harness, bridle and some type of vehicle. Work. There are certain jobs that horses do very well, and no technology has yet developed that can fully replace them. For example, mounted police horses are still effective for certain types of patrol duties and crowd control. Cattle ranches still require riders on horseback to round up cattle that are scattered across remote, rugged terrain. Search and rescue organizations in some countries depend upon mounted teams to locate people, particularly hikers and children, and to provide disaster relief assistance. Horses can also be used in other areas where it is necessary to avoid vehicular disruption to delicate soil. Examples include areas such as nature reserves. They may also be the only form of transport allowed in wilderness areas. They are also quieter than motorized vehicles. Law enforcement officers such as park rangers or game wardens may use horses for patrols, and horses or mules may also be used for clearing trails or other work in areas of rough terrain where vehicles are less effective. Some land management practices such as cultivating and logging can be efficiently performed with horses. In agriculture, less use of fossil fuels and increased environmental conservation can be seen over time with the use of draft animals such as horses. In forestry, logging can be done with horses and can result in reduced damage to soil structure and less damage to trees due to more selective logging. Although machinery has replaced horses in many parts of the world, an estimated 100 million horses, donkeys and mules are still used for agriculture and transportation in less developed areas such as Morocco, Kenya and Guatemala. Entertainment and culture. Modern horses are often used to reenact many of their historical work purposes. Horses are used, complete with equipment that is authentic or a meticulously recreated replica, in various live action historical reenactments of specific periods of history, especially recreations of famous battles. Horses also are used to preserve cultural traditions and for ceremonial purposes. Countries such as the United Kingdom still use horse-drawn carriages to convey royalty and other VIPs to and from certain culturally significant events. Public exhibitions are another example, such as the Budweiser Clydesdales, seen in parades and other public settings, a team of draft horses that pull a beer wagon similar to that used before to the invention of the modern motorized truck. Horses are frequently used in television and films to add authenticity to historical dramas as well as adding charm to films set in modern-day, or even futuristic science fiction settings. Both live horses and iconic images of horses are used in advertising to promote a variety of products. The horse frequently appears in coats of arms in heraldry. The horse can be represented as standing, trotting, courant (running) or salient (rearing). The horse may be saddled and bridled, harnessed, or without any harness whatsoever. The horse appears in the 12-year cycle of animals in the Chinese zodiac related to the Chinese calendar. According to Chinese folklore, each animal is associated with certain personality traits, and those born in the year of the horse are intelligent, independent and free-spirited. Assisted learning and therapy. People of all ages with physical and mental disabilities obtain beneficial results from association with horses. Therapeutic riding is used to mentally and physically stimulate disabled persons and help them improve their lives through improved balance and coordination, increased self-confidence and a greater feeling of freedom and independence. The benefits of equestrian activity for people with disabilities has also been recognized with the addition of equestrian events to the Paralympic Games and recognition of para-equestrian events by the FEI. Hippotherapy and therapeutic horseback riding are names for different physical, occupational, and speech therapy treatment strategies that utilize equine movement. In hippotherapy, a therapist uses the horse's movement to provide improve their patient's cognitive, coordination, balance and fine motor skills, whereas therapeutic horseback riding uses specific riding skills. Horses also provide psychological benefits to people whether they actually ride or not. "Equine-assisted" or "equine-facilitated" psychotherapy is a form of experiential psychotherapy that uses horses as companion animals to assist people with psychological problems, including anxiety disorders, psychotic disorders, mood disorders, behavioral difficulties, mental illness and those who are going through major life changes. Equine Assisted Learning (EAL) (also known as equine guided education or equine assisted professional development) is a field of experiential learning for corporate, professional and personal development. There are also experimental programs using horses in prison settings. Exposure to horses appears to improve the behavior of inmates in a prison setting and help reduce recidivism when they leave. Warfare. Horses in warfare have been seen for most of recorded history. The first archaeological evidence of horses used in warfare dates to between 3000 to 4000 BC, and the use of horses in warfare was widespread by the end of the Bronze Age. Although mechanization has largely replaced the horse as a weapon of war, horses are still seen today in limited military uses, mostly for ceremonial purposes, or for reconnaissance and transport activities in areas of rough terrain where motorized vehicles are ineffective. Horses have been used in the 21st century by the Janjaweed militias in the War in Darfur. Products. Horses have been used as raw material for many products made by humans throughout history, including byproducts from the slaughter of horses as well as materials collected from living horses. Products collected from living horses include mare's milk, used by people with large horse herds, such as the Mongols, who let it ferment to produce kumis. Horse blood was once used as food by the Mongols and other nomadic tribes, who found it a convenient source of nutrition when traveling. Drinking their own horses' blood allowed the Mongols to ride for extended periods of time without stopping to eat. Today, the drug Premarin is a mixture of estrogens extracted from the urine of pregnant mares (pre'"gnant "'mar'"es' ur"'in'"e). It is a widely used drug for hormone replacement therapy. The tail hair of horses can be used for making bows for string instruments such as the violin, viola, cello, and double bass. Horse meat has been used as food for humans and carnivorous animals throughout the ages. It is eaten in many parts of the world, though consumption is taboo in some cultures. Horsemeat has been an export industry in the United States and other countries, though legislation has periodically been introduced in the United States Congress which would end export from the United States. Horsehide leather has been used for boots, gloves, jackets, baseballs, and baseball gloves. Horse hooves can also be used to produce animal glue. Horse bones can be used to make implements. Specifically, in Italian cuisine, the horse tibia is sharpened into a probe called a "spinto", which is used to test the readiness of a (pig) ham as it cures. In Asia, the saba is a horsehide vessel used in the production of kumis. Care. Horses are grazing animals, and their major source of nutrients is good-quality forage from hay or pasture. They can consume approximately 2% to 2.5% of their body weight in dry feed each day. Therefore, a adult horse could eat up to of food. Sometimes, concentrated feed such as grain is fed in addition to pasture or hay, especially when the animal is very active. When grain is fed, equine nutritionists recommend that 50% or more of the animal's diet by weight should still be forage. Horses require a plentiful supply of clean water, a minimum of to per day. Although horses are adapted to live outside, they require shelter from the wind and precipitation, which can range from a simple shed or shelter to an elaborate stable. Horses require routine hoof care from a farrier as well as regular vaccinations to protect against various diseases, and periodic dental examinations from a veterinarian or a specialized equine dentist. If horses are kept inside in a barn, they require regular daily exercise for their physical health and mental well-being. When turned outside, they require well-maintained, sturdy fences to be safely contained. Regular grooming is also helpful to help the horse maintain good health of the hair coat and underlying skin.