Instruct: Given a question, retrieve relevant passages that answer the question.
Query: How large is a cat's brain?
The brain of the domesticated cat is about long, and weighs . If a typical cat is taken to be long with a weight of , then the brain would be at 0.91% of its total body mass, compared to 2.33% of total body mass in the average human. Within the encephalization quotient proposed by Jerison in 1973, values above 1 are classified big brained, while values lower than 1 are small brained. The domestic cat is attributed a value of between 1–1.71 relative to human value that is 7.44–7.8. The largest brains in the Felidae family are those of the tigers in Java and Bali, of which the largest relative brain size within the "panthera" is the "tigris". It is debated whether there exists a causal relationship between brain size and intelligence in vertebrates. Correlations have been shown between these factors in a number of experiments. However, correlation does not imply causation. Most experiments involving the relevance of brain size to intelligence hinge on the assumption that complex behavior requires a complex (and therefore intelligent) brain; however, this connection has not been consistently demonstrated.
Cats have historically been associated with magic, and have been revered by various human cultures, the ancient Egyptians worshipping them as gods and the creatures being feared as demons in ancient Japan, such as the "bakeneko". 
Vogue magazine has suggested that the popularity of cats on the internet is culturally-specific, being popular in North America, Western Europe, and Japan. Other nations favor different animals online, Ugandans sharing images of goats and chickens, Mexicans preferring llamas, and Chinese internet users sharing images of the river crab and grass-mud horse due to double-meanings of their names allowing them to "subvert government Internet censors". While cats on the internet might be culturally-specific, cat content is increasing in its popularity in various cultures as a scientific study showed by looking at German, English, Italian, and Russian media.
Cats often purr when distressed or in pain, such as in labour. This purring may trigger a cat's brain to release a hormone which helps it in relaxing and acts as a painkiller. Purring may also be a healing mechanism to offset long periods of rest and sleep that would otherwise contribute to a loss of bone density. The vibrations and contractions of a purr show a consistent pattern and frequency around 25 Hz; these frequencies have been shown to improve bone density and promote healing in animal models and humans.
A fully-grown "Smilodon" weighed approximately and had a short tail, powerful legs, and a large head. The cats have two huge canine teeth, about long, that are used to kill prey by suffocation. The jaws could open to about 120 degrees in order to use these fangs to deadly effect. They would die out due to climate change.
The brain of "Smilodon" had sulcal patterns similar to modern cats, which suggests an increased complexity of the regions that control the sense of hearing, sight, and coordination of the limbs. Felid saber-tooths in general had relatively small eyes that were not as forward-facing as those of modern cats, which have good binocular vision to help them move in trees. "Smilodon" was likely an ambush predator that concealed itself in dense vegetation, as its limb proportions were similar to modern forest dwelling cats, and its short tail would not have helped it balance while running. Unlike its ancestor "Megantereon", which was at least partially scansorial and therefore able to climb trees, "Smilodon" was probably completely terrestrial due to its greater weight and lack of climbing adaptations. The heel bone of "Smilodon" was fairly long, which suggests it was a good jumper. Its well-developed flexor and extensor muscles in its forearms probably enabled it to pull down, and securely hold down, large prey. Analysis of the cross-sections of "S. fatalis" humeri indicated that they were strengthened by cortical thickening to such an extent that they would have been able to sustain greater loading than those of extant big cats, or of the extinct American lion. The thickening of "S. fatalis" femurs was within the range of extant felids. Its canines were fragile and could not have bitten into bone; due to the risk of breaking, these cats had to subdue and restrain their prey with their powerful forelimbs before they could use their canine teeth, and likely used quick slashing or stabbing bites rather than the slow, suffocating bites typically used by modern cats. On rare occasions, as evidenced by fossils, "Smilodon" was willing to risk biting into bone with its canines. This may have been focused more towards competition such as other "Smilodon" or potential threats such as other carnivores than on prey.
Debate continues as to how "Smilodon" killed its prey. Traditionally, the most popular theory is that the cat delivered a deep stabbing bite or open-jawed stabbing thrust to the throat, generally cutting through the jugular vein and/or the trachea and thus killing the prey very quickly. Another hypothesis suggests that "Smilodon" targeted the belly of its prey. This is disputed, as the curvature of their prey's belly would likely have prevented the cat from getting a good bite or stab. In regard to how "Smilodon" delivered its bite, the "canine shear-bite" hypothesis has been favored, where flexion of the neck and rotation of the skull assisted in biting the prey, but this may be mechanically impossible. The mandibular flanges may have helped resist bending forces when the mandible was pulled against the hide of a prey. The protruding incisors were arranged in an arch, and were used to hold the prey still and stabilize it while the canine bite was delivered. The contact surface between the canine crown and the gum was enlarged, which helped stabilize the tooth and helped the cat sense when the tooth had penetrated to its maximum extent. Since saber-toothed cats generally had a relatively large infraorbital foramen (opening) in the skull, which housed nerves associated with the whiskers, it has been suggested the improved senses would have helped the cats' precision when biting outside their field of vision, and thereby prevent breakage of the canines. The blade-like carnassial teeth were used to cut skin to access the meat, and the reduced molars suggest that they were less adapted for crushing bones than modern cats. As the food of modern cats enters the mouth through the side while cutting with the carnassials, not the front incisors between the canines, the animals do not need to gape widely, so the canines of "Smilodon" would likewise not have been a hindrance when feeding.
During the second half of the first millennium BC, the Ancient Greeks developed differing views on the function of the brain. However, due to the fact that Hippocratic doctors did not practice dissection, because the human body was considered sacred, Greek views of brain function were generally uninformed by anatomical study. It is said that it was the Pythagorean Alcmaeon of Croton (6th and 5th centuries BC) who first considered the brain to be the place where the mind was located. According to ancient authorities, "he believed the seat of sensations is in the brain. This contains the governing faculty. All the senses are connected in some way with the brain; consequently they are incapable of action if the brain is disturbed...the power of the brain to synthesize sensations makes it also the seat of thought: The storing up of perceptions gives memory and belief and when these are stabilized you get knowledge." In the 4th century BC Hippocrates, believed the brain to be the seat of intelligence (based, among others before him, on Alcmaeon's work). During the 4th century BC Aristotle thought that, while the heart was the seat of intelligence, the brain was a cooling mechanism for the blood. He reasoned that humans are more rational than the beasts because, among other reasons, they have a larger brain to cool their hot-bloodedness.
Cats in ancient Egypt were valued very highly and were seen to be very close to the gods. They believed the cats were an embodiment of the goddess Bastet. Harming a cat in ancient Egypt was an offense punishable by death. When a cat died the Egyptians would mummify and bury their cats as an offering to the gods.
One hypothesis, backed by electromyographic studies, is that cats produce the purring noise by using the vocal folds or the muscles of the larynx to alternately dilate and constrict the glottis rapidly, causing air vibrations during inhalation and exhalation. Combined with the steady inhalation and exhalation of air as the cat breathes, a purring noise is produced with strong harmonics.
The mechanism of how cats purr is elusive. This is partly because cats do not have a unique anatomical feature that is clearly responsible for this vocalization. One hypothesis, supported by electromyographic studies, is that cats produce the purring noise by using the vocal folds and/or the muscles of the larynx to alternately dilate and constrict the glottis rapidly, causing air vibrations during inhalation and exhalation. Combined with the steady inhalation and exhalation as the cat breathes, a purring noise is produced with strong harmonics. Purring is sometimes accompanied by other sounds, though this varies between individuals. Some may only purr, while other cats also emit low level outbursts sometimes described as "lurps" or "yowps".
Overall, "Smilodon" was more robustly built than any extant cat, with particularly well-developed forelimbs and exceptionally long upper canine teeth. Its jaw had a bigger gape than that of modern cats, and its upper canines were slender and fragile, being adapted for precision killing. "S. gracilis" was the smallest species at in weight. "S. fatalis" had a weight of and height of . Both of these species are mainly known from North America, but remains from South America have also been attributed to them. "S. populator" from South America was the largest species, at in weight and in height, and was among the largest known felids. The coat pattern of "Smilodon" is unknown, but it has been artistically restored with plain or spotted patterns.
It has been postulated that domestic cats can learn to manipulate their owners through vocalizations that are similar to the cries of human babies. Some cats learn to add a purr to the vocalization, which makes it less harmonious and more dissonant to humans, and therefore harder to ignore. Individual cats learn to make these vocalizations through trial-and-error; when a particular vocalization elicits a positive response from a human, the probability increases that the cat will use that vocalization in the future.
Domestic cats purr at varying frequencies. One study reported that domestic cats purr at average frequencies of 21.98 Hz in the egressive phase and 23.24 Hz in the ingressive phase with an overall mean of 22.6 Hz. Further research on purring in four domestic cats found that the fundamental frequency varied between 20.94 and 27.21 Hz for the egressive phase and between 23.0 and 26.09 Hz for the ingressive phase. There was considerable variation between the four cats in the relative amplitude, duration and frequency between egressive and ingressive phases, although this variation generally occurred within the normal range.
The best-known musical adaptation of the poems is Andrew Lloyd Webber's musical "Cats", which was premiered in the West End of London in 1981 and on Broadway in 1982. It became the longest-running Broadway show in history until it was overtaken by another musical by Lloyd Webber, "The Phantom of the Opera", and then by "Chicago". As well as the characters found in the book, "Cats" introduces several additional characters from Eliot's unpublished drafts, most notably Grizabella. A film adaptation of "Cats" is due for release on December 20, 2019.
"Brontosaurus" was a large, long-necked quadrupedal animal with a long, whip-like tail, and forelimbs that were slightly shorter than its hindlimbs. The largest species, "B. excelsus", weighed up to and measured up to long from head to tail. For comparison, the current largest land animal, the average male African bush elephant is 3.20 m (10.5 ft) tall at the shoulder and has a body mass of 6,000 kg (13,228 lb) or 6.6 short tons.
The signs of diabetes mellitus are caused by a persistently high blood glucose concentration, which may be caused by either insufficient insulin, or by a lack of response to insulin. Most cats have a type of diabetes mellitus similar to human diabetes mellitus type 2, with β-cell dysfunction and insulin resistance. Factors which contribute to insulin resistance include obesity and endocrine diseases such as acromegaly. Acromegaly affects 20–30% of diabetic cats; it can be diagnosed by measuring the concentration of insulin-like growth factor-1 (IGF-1) in the blood.
The Bhitarkanika Mangroves are home to 55 of India's 58 known mangrove species. The mangroves harbor one of India's largest populations of saltwater crocodiles, and Gahirmatha Beach, which separates the mangroves from the Bay of Bengal, is the world's most important nesting beach for olive ridley sea turtles. Some wildlife experts are of the opinion that the largest saltwater crocodile ever was in Bhitarkanika, measuring an estimated 23 feet (7.0 m) which could be traced from the skull preserved by the Kanika Royal Family. The crocodile was shot near Dhamara in 1926, and later its skull was preserved by the then Kanika King. Crocodile experts estimate the animal to have been between 20 feet (6.1 m) and 23 feet (7.0 m) long, as the size of the skull was measured one ninth of the total length of the body. In 2006 the park was recognized by the "Guinness Book of World Records" for the largest white crocodile living in captivity also measuring 23 feet. The wetland also hosts a large and diverse population of resident and migratory birds. Rhesus monkey, leopard cat, fishing cat, jungle cat, small Indian civet cat, toddy cat, common mongoose, jackal, striped hyena, Indian fox, wild pig, Indian porcupine, mole rat, long tailed tree mouse, spotted deer, sambar, common otter, smooth Indian otter are also found here.
The general bite-and-retreat hypothesis has been criticised because of its bloodiness and because the struggling prey would have attracted any predators and scavengers in the area. The idea that a single animal would wound, release, and follow a prey animal has been counteracted more strongly. Cats rarely walk away from prey until they have eaten their fill and it would have risked being stolen by other predators.
Rodents make up the largest order of mammals, with over 40 percent of mammalian species. They have two incisors in the upper and lower jaw which grow continually and must be kept short by gnawing. Most rodents are small though the capybara, a rodent native to South America, can weigh up to 45 kg (100 lb).
Cats is a 1998 direct-to-video musical film based on the stage musical "Cats" by Andrew Lloyd Webber, itself based on the novel "Old Possum's Book of Practical Cats" by T. S. Eliot. Lloyd Webber himself personally oversaw orchestration for the film and called on Gillian Lynne, the original show's choreographer, to personally train the cast for the film. Trevor Nunn, the original director, did not serve as the director of this production.
Domestic cats have barbed penises, with about 120–150 one millimeter long backwards-pointing spines. Upon withdrawal of the penis, the spines rake the walls of the female's vagina, which is a trigger for ovulation. Lions also have barbed penises. Male felids urinate backwards by curving the tip of the glans penis backward. When male cheetahs urine-mark their territories, they stand one meter away from a tree or rock surface with the tail raised, pointing the penis either horizontally backward or 60° upward.
The purr is a continuous, soft, vibrating sound made in the throat by most species of felines. Domestic kittens can purr as early as two days of age. This tonal rumbling can characterize different personalities in domestic cats. Purring is often believed to indicate a positive emotional state, but cats sometimes purr when they are ill, tense, or experiencing traumatic or painful moments such as giving birth. A more expansive definition is "purring signals a friendly social mood, and it can be given as a signal to, say, a vet from an injured cat indicating the need for friendship, or as a signal to an owner, saying thank you for friendship given."
In November 2009, scientists claimed to simulate a cat's brain using a supercomputer containing 24,576 processors. This experiment did not simulate the function of the individual neurons in the brain, nor their synaptic patterns. It was intended to demonstrate that the problem of simulating a biological brain could be scaled to very large supercomputer platforms. However, the approach has been criticised as flawed.
In mammals, neurons in the brain that process vision actually develop after birth based on signals from the eyes. A landmark experiment by David H. Hubel and Torsten Wiesel (1963) showed that cats that had one eye sewn shut from birth to three months of age (monocular deprivation) only fully developed vision in the open eye. They showed that columns in the primary visual cortex receiving inputs from the other eye took over the areas that would normally receive input from the deprived eye. In general electrophysiological analyses of axons and neurons in the lateral geniculate nucleus showed that the visual receptive field properties was comparable to adult cats. However, the layers of cortex that were deprived had less activity and fewer responses were isolated. The kittens had abnormally small ocular dominance columns (part of the brain that processes sight) connected to the closed eye, and abnormally large, wide columns connected to the open eye. Because the critical period time had elapsed, it would be impossible for the kittens to alter and develop vision in the closed eye. This did not happen to adult cats even when one eye was sewn shut for a year because they had fully developed their vision during their critical period. Later experiments in monkeys found similar results.
The skull is longer and more narrow than that of a domestic cat. When compared to the leopard cat's skull, the Iriomote cat's is roughly the same size but thicker. Because of this, the Iriomote cat's brain is smaller; a male leopard cat's brain is about 42 grams, whereas a male Iriomote cat's brain is about 30 grams. The occipital bone of the skull and the auditory capsule are not connected. The mandibular symphysis is short.
Another factor affecting relative brain size is sociality and flock size. For example, dogs (a social species) have a higher EQ than cats (a mostly solitary species). Animals with very large flock size and/or complex social systems consistently score high EQ, with dolphins and orcas having the highest EQ of all cetaceans, and humans with their extremely large societies and complex social life topping the list by a good margin.