How large is a cat's brain?
Cat intelligence
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.
Pizzicato Pussycat
Suddenly there is a flurry of media activity around the house. The cat is examined by scientists, but they are unable to find anything abnormal about the cat; for instance, an x-ray of his brain shows it (humorously) to be the size of a peanut.
Cat intelligence
The surface area of a cat's cerebral cortex is approximately whereas the human brain has a surface area of about . Furthermore, a theoretical cat weighing has a cerebellum weighing , 0.17% of the total weight.
Cat
Cats have excellent hearing and can detect an extremely broad range of frequencies. They can hear higher-pitched sounds than either dogs or humans, detecting frequencies from 55 Hz to 79,000 Hz, a range of 10.5 octaves, while humans and dogs both have ranges of about 9 octaves. Cats can hear ultrasound, which is important in hunting because many species of rodents make ultrasonic calls. However, they do not communicate using ultrasound like rodents do. Cats' hearing is also sensitive and among the best of any mammal, being most acute in the range of 500 Hz to 32 kHz. This sensitivity is further enhanced by the cat's large movable outer ears (their pinnae), which both amplify sounds and help detect the direction of a noise.
Cat cognitive support diets
Omega-3 fatty acid also aids in uptake of glucose in the brain which is needed for energy for cognitive health. Though no studies in cats have been completed, it was found that rats with low levels of omega-3 fatty acids resulted in a decrease of glucose uptake in the brain.
Brain size
The volume of the human braincase has increased as humans have evolved (see Homininae), starting from about 600 cm in "Homo habilis" up to 1740 cm in "Homo neanderthalensis", which was the hominin with the biggest brain size.
Bekenstein bound
An average human brain has a mass of 1.5 kg and a volume of 1260 cm. If the brain is approximated by a sphere, then the radius will be 6.7 cm.
Wildcat
Compared to other members of the "Felinae", the wildcat is a small species, but is nonetheless larger than the housecat. The wildcat is similar in appearance to a striped tabby cat, but has relatively longer legs, a more robust build, and a greater cranial volume. The tail is long, and usually slightly exceeds one-half of the animal's body length. Its skull is more spherical in shape than that of the jungle and leopard cat. The ears are moderate in length, and broad at the base. The eyes are large, with vertical pupils, and yellowish-green irises. Its dentition is relatively smaller and weaker than the jungle cat's. The species size varies according to Bergmann's rule, with the largest specimens occurring in cool, northern areas of Europe (such as Scotland and Scandinavia) and of Middle Asia (such as Mongolia, Manchuria and Siberia). Males measure in body length, in tail length, and normally weigh . Females are slightly smaller, measuring in body length and in tail length, and weighing .
Both sexes possess pre-anal glands, which consist of moderately sized sweat and sebaceous glands around the anal opening. Large-sized sebaceous and scent glands extend along the full length of the tail on the dorsal side. Male wildcats have pre-anal pockets located on the tail, which are activated upon reaching sexual maturity. These pockets play a significant role in reproduction and territorial marking. The species has two thoracic and two abdominal teats. The wildcat has good night vision, having 20 to 100% higher retinal ganglion cell densities than the housecat. It may have colour vision as the densities of its cone receptors are more than 100% higher than in the housecat. Its sense of smell is acute, and it can detect meat at up to 200 metres. The wildcat's whiskers are white; they can reach 5 to 8 cm in length on the lips, and number 7 to 16 on each side. The eyelashes range from 5 to 6 cm in length, and can number 6 to 8 per side. Whiskers are also present on the inner surface of the wrist, and can measure 3 to 4 cm.
Asian golden cat
The Asian golden cat is heavily built, with a typical cat-like appearance. It has a head-body length of , with a tail long, and is tall at the shoulder. The weight ranges from , which is about two or three times that of a domestic cat.
Cat senses
A cat has about twenty-four movable vibrissae ("whiskers"), in four sets on each upper lip on either side of its nose (some cats may have more). There are also a few on each cheek, tufts over the eyes, bristles on the chin, the cat's inner "wrists", and at the back of the legs. The Sphynx (a nearly hairless breed) may have full length, short, or no whiskers at all.
Neanderthal
Neanderthals are known for their large cranial capacity, which at is larger on average than that of modern humans. One study has found that drainage of the dural venous sinuses (low pressure blood vessels that run between the meninges and skull leading down through the skull) in the occipital lobe region of Neanderthal brains appears more asymmetric than other hominid brains. In 2008, a group of scientists produced a study using three-dimensional computer-assisted reconstructions of Neanderthal infants based on fossils found in Russia and Syria. It indicated that Neanderthal and modern human brains were the same size at birth, but that by adulthood, the Neanderthal brain was larger than the modern human brain. They had almost the same degree of encephalisation (i.e. brain-to-body-size ratio) as modern humans.
Human brain
The human brain has many properties that are common to all vertebrate brains. Many of its features are common to all mammalian brains, most notably a six-layered cerebral cortex and a set of associated structures, including the hippocampus and amygdala. The cortex is proportionally larger in greater mammals and humans than many other mammals. Humans have more association cortex, sensory and motor parts than smaller mammals such as the rat and the cat.
Dolphin
Brain size was previously considered a major indicator of the intelligence of an animal. Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. Allometric analysis indicates that mammalian brain size scales at approximately the ⅔ or ¾ exponent of the body mass. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an encephalization quotient that can be used as another indication of animal intelligence. Killer whales have the second largest brain mass of any animal on earth, next to the sperm whale. The brain to body mass ratio in some is second only to humans.
Cat
Cats have excellent night vision and can see at only one-sixth the light level required for human vision. This is partly the result of cat eyes having a tapetum lucidum, which reflects any light that passes through the retina back into the eye, thereby increasing the eye's sensitivity to dim light. Another adaptation to dim light is the large pupils of cats' eyes. Unlike some big cats, such as tigers, domestic cats have slit pupils. These slit pupils can focus bright light without chromatic aberration, and are needed since the domestic cat's pupils are much larger, relative to their eyes, than the pupils of the big cats. At low light levels, a cat's pupils will expand to cover most of the exposed surface of its eyes. However, domestic cats have rather poor color vision and (like most nonprimate mammals) have only two types of cones, optimized for sensitivity to blue and yellowish green; they have limited ability to distinguish between red and green. A 1993 paper reported a response to middle wavelengths from a system other than the rods which might be due to a third type of cone. However, this appears to be an adaptation to low light levels rather than representing true trichromatic vision.
King-Size Canary
The mouse in the house takes a few sips of plant food, instantly ballooning to gigantic size. The dog chases the cat to the city, only for the now gargantuan mouse to show up and scare the bulldog away with a simple "Boo!". The mouse who is as tall as a 20 story building and just as fat, reminds the cat that he told him he would save his life. The cat thanks him as the mouse hands him the bottle back and waddles off. The cat, rubs his enormous belly realizing he still is hungry, sees the huge mouse stomping off and gets another idea. He suddenly drinks more of the formula and grows even bigger and fatter than the mouse. The cat who is by now 100 stories tall, chases the giant but smaller mouse through the city and across the country, passing the Grand Canyon, Hoover Dam and the mountains.
Brain size
Brain size tends to vary according to body size. The relationship is not proportional, however; the brain-to-body mass ratio varies. The largest ratio found is in the shrew. Averaging brain weight across all orders of mammals, it follows a power law, with an exponent of about 0.75. This power law formula applies to the "average" brain of mammals taken as a whole, but each family (cats, rodents, primates, etc.) departs from it to some degree, in a way that generally reflects the overall "sophistication" of behavior. Primates, for a given body size, have brains 5 to 10 times as large as the formula predicts. Predators tend to have relatively larger brains than the animals they prey on; placental mammals (the great majority) have relatively larger brains than marsupials such as the opossum.
Asian cat
It is a medium-sized cat with a muscular and compact body devoid of fat. It has a broad, rounded chest and slender legs. Its tail is a medium length. The pleasantly rounded head has no flattened areas, and there is a very visible spot in its profile. This gives the Asian a full-looking face. The round and wide-set eyes come in the colour of yellow. Females aren't quite as big as the males. They can weigh anywhere from 6–13 pounds.
Brain
Here is a list of some of the most important vertebrate brain components, along with a brief description of their functions as currently understood:The most obvious difference between the brains of mammals and other vertebrates is in terms of size. On average, a mammal has a brain roughly twice as large as that of a bird of the same body size, and ten times as large as that of a reptile of the same body size.
Cat
Cats have relatively few taste buds compared to humans (470 or so versus more than 9,000 on the human tongue). Domestic and wild cats share a gene mutation that keeps their sweet taste buds from binding to sugary molecules, leaving them with no ability to taste sweetness. Their taste buds instead respond to acids, amino acids like protein, and bitter tastes. Cats also have a distinct temperature preference for their food, preferring food with a temperature around which is similar to that of a fresh kill and routinely rejecting food presented cold or refrigerated (which would signal to the cat that the "prey" item is long dead and therefore possibly toxic or decomposing).
To aid with navigation and sensation, cats have dozens of movable whiskers (vibrissae) over their body, especially their faces. These provide information on the width of gaps and on the location of objects in the dark, both by touching objects directly and by sensing air currents; they also trigger protective blink reflexes to protect the eyes from damage.
Cat senses
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 1 octave above the range of a dog. When listening for something, a cat's ears will swivel in that direction; a cat's ear flaps (pinnae) can independently point backwards as well as forwards and sideways to pinpoint the source of the sound. Cats can judge within the location of a sound being made away—this can be useful for locating their prey.
Cat intelligence
Taurine is an amino acid, which is essential in cat diets due to their low capacity to synthesize it. Because taurine has the ability to cross the blood–brain barrier in the brain, it has been found to have a role in many neurological functions, especially in the visual development. Without taurine, felines can have an abnormal morphology in the cerebellum and visual cortex. When cats were fed a diet deficient in taurine, this leads to a decrease in the concentration of taurine in the retina of the eye. This results in deterioration of the photoreceptors, followed by complete blindness.
Sperm whale
The brain is the largest known of any modern or extinct animal, weighing on average about , more than five times heavier than a human's, and has a volume of about 8,000 cm. Although larger brains generally correlate with higher intelligence, it is not the only factor. Elephants and dolphins also have larger brains than humans. The sperm whale has a lower encephalization quotient than many other whale and dolphin species, lower than that of non-human anthropoid apes, and much lower than humans'.
Human interaction with cats
Cats can also come in several body types, ranging between two extremes:Because of their small size, domesticated house cats pose little physical danger to adult humans. However, in the USA cats inflict about 400,000 bites per year. This number represents about one in ten of all animal bites. Many cat bites will become infected, sometimes with serious consequences such as cat-scratch disease, or, more rarely, rabies. Cats may also pose a danger to pregnant women and immunosuppressed individuals, since their feces can transmit toxoplasmosis. A large percentage of cats are infected with this parasite, with infection rates ranging from around 40 to 60% in both domestic and stray cats worldwide. Research indicates a correlation between the parasite "Toxoplasma gondii", which sexually reproduces exclusively in cats, and numerous human psychiatric conditions, including OCD. The compulsive hoarding of cats, a symptom of obsessive compulsive disorder (OCD), has long been associated with "crazy cat ladies".
Coati
Adult coatis measure from head to the base of the tail, which can be as long as their bodies. Coatis are about tall at the shoulder and weigh between , about the size of a large house cat. Males can become almost twice as large as females and have large, sharp canine teeth. The above measurements are for the white-nosed and South America coatis. The two mountain coatis are smaller.
Smilodon
Another argument for sociality is based on the healed injuries in several "Smilodon" fossils, which would suggest that the animals needed others to provide it food. This argument has been questioned, as cats can recover quickly from even severe bone damage and an injured "Smilodon" could survive if it had access to water. The brain of "Smilodon" was relatively small compared to other cat species. Some researchers have argued that "Smilodon"'s brain would have been too small for it to have been a social animal. An analysis of brain size in living big cats found no correlation between brain size and sociality. Another argument against "Smilodon" being social is that being an ambush hunter in closed habitat would likely have made group-living unnecessary, as in most modern cats. Yet it has also been proposed that being the largest predator in an environment comparable to the savanna of Africa, "Smilodon" may have had a social structure similar to modern lions, which possibly live in groups primarily to defend optimal territory from other lions (lions are the only social big cats today).
Human brain
Other animals, including whales and elephants have larger brains than humans. However, when the brain-to-body mass ratio is taken into account, the human brain is almost twice as large as that of a bottlenose dolphin, and three times as large as that of a chimpanzee. However, a high ratio does not of itself demonstrate intelligence: very small animals have high ratios and the treeshrew has the largest quotient of any mammal.
Pulvinar nuclei
The pulvinar varies in importance in different animals: it is virtually nonexistent in the rat, and grouped as the lateral posterior-pulvinar complex with the lateral posterior thalamic nucleus due to its small size in cats. In humans it makes up roughly 40% of the thalamus making it the largest of its nuclei. Significant research has been undertaken in the marmoset examining the role of the retinorecipient region of the inferior pulvinar (medial subdivision), which projects to visual cortical area MT, in the early development of MT and the dorsal stream, as well as following early-life lesions of the primary visual cortex (V1).
Whale
Brain size was previously considered a major indicator of the intelligence of an animal. Since most of the brain is used for maintaining bodily functions, greater ratios of brain to body mass may increase the amount of brain mass available for more complex cognitive tasks. Allometric analysis indicates that mammalian brain size scales at approximately the ⅔ or ¾ exponent of the body mass. Comparison of a particular animal's brain size with the expected brain size based on such allometric analysis provides an encephalisation quotient that can be used as another indication of animal intelligence. Sperm whales have the largest brain mass of any animal on earth, averaging and in mature males, in comparison to the average human brain which averages in mature males. The brain to body mass ratio in some odontocetes, such as belugas and narwhals, is second only to humans.
Brain size
Hominins
Manot 1
Manot 1 is an adult individual represented by an almost complete skullcap (calvaria) very similar to those of modern humans. But it has a relatively small brain size, which is estimated at around 1,100 mL, compared to modern human brain which is about 1,400 mL. Its unique features are the bun-shaped occipital, the moderate arch of the parietals, flat sagittal area, presence of a suprainiac fossa, and the pronounced superior nuchal line. These combined features indicate that it shares a number of features between the most recent African humans and those of European from the Upper Paleolithic period. But it has notable differences from those of other archaic humans found in the neighbouring Levant. The discoverers concluded that:
Homininae
There has been a gradual increase in brain volume (brain size) as the ancestors of modern humans progressed along the timeline of human evolution, starting from about 600 cm in "Homo habilis" up to 1500 cm in "Homo neanderthalensis". However, modern "Homo sapiens" have a brain volume slightly smaller (1250 cm) than Neanderthals, women have a brain slightly smaller than men and the Flores hominids ("Homo floresiensis"), nicknamed hobbits, had a cranial capacity of about 380 cm (considered small for a chimpanzee), about a third of the "Homo erectus" average. It is proposed that they evolved from "H. erectus" as a case of insular dwarfism. In spite of their smaller brain, there is evidence that "H. floresiensis" used fire and made stone tools at least as sophisticated as those of their proposed ancestors "H. erectus". In this case, it seems that for intelligence, the structure of the brain is more important than its size.
Human brain
The adult human brain weighs on average about which is about 2% of the total body weight, with a volume of around 1260 cm in men and 1130 cm in women, although there is substantial individual variation. Neurological differences between the sexes have not been shown to correlate in any simple way with IQ or other measures of cognitive performance.
Cat intelligence
Grouse "et al." 1979 ascertained the neuroplasticity of kittens' brains, with respect to control of visual stimulus correlated with changes in RNA structures. In a later study, it was found that cats possess visual-recognition memory, and have flexibility of cerebral encoding from visual information.
Microcephaly
Microcephaly generally is due to the diminished size of the largest part of the human brain, the cerebral cortex, and the condition can arise during embryonic and fetal development due to insufficient neural stem cell proliferation, impaired or premature neurogenesis, the death of neural stem cells or neurons, or a combination of these factors. Research in animal models such as rodents has found many genes that are required for normal brain growth. For example, the Notch pathway genes regulate the balance between stem cell proliferation and neurogenesis in the stem cell layer known as the ventricular zone, and experimental mutations of many genes can cause microcephaly in mice, similar to human microcephaly. Mutations of the abnormal spindle-like microcephaly-associated (ASPM) gene are associated with microcephaly in humans and a knockout model has been developed in ferrets that exhibits severe microcephaly. In addition, viruses such as cytomegalovirus (CMV) or Zika have been shown to infect and kill the primary stem cell of the brain—the radial glial cell, resulting in the loss of future daughter neurons. The severity of the condition may depend on the timing of infection during pregnancy.
List of The Ren &amp; Stimpy Show characters
Stimpson "Stimpy" J. Cat is a fat, red and white Cornish Rex cat (described by George Liquor as a "Cornish Rex Hound" to enter him in a dog show) with a large blue nose, purple eyelids, no tail, white gloves with fingernails on them, human-style buttocks, flat feet and a brain the size of a peanut (despite some intelligence, such as when cooking and inventing). Martin "Dr. Toon" Goodman of Animation World Magazine described Stimpy as "obese" and "brain-damaged". Andy Meisler of "The New York Times" described Stimpy as "barrel-chested" and "good-natured".
Neuron
The human brain has a huge number of synapses. Each of the 10 (one hundred billion) neurons has on average 7,000 synaptic connections to other neurons. It has been estimated that the brain of a three-year-old child has about 10 synapses (1 quadrillion). This number declines with age, stabilizing by adulthood. Estimates vary for an adult, ranging from 10 to 5 x 10 synapses (100 to 500 trillion).
In 1937, John Zachary Young suggested that the squid giant axon could be used to study neuronal electrical properties. Being larger than but similar in nature to human neurons, squid cells were easier to study. By inserting electrodes into the giant squid axons, accurate measurements were made of the membrane potential.
Cat senses
A domestic cat's sense of smell is about fourteen times as strong as humans'. Cats have twice as many receptors in the olfactory epithelium (i.e. smell-sensitive cells in their noses) as people do, meaning that cats have a more acute sense of smell than humans. In fact cats have 200 million odor-sensitive cells in their noses where as humans only have 5 million odor-sensitive cells. Cats also have a scent organ in the roof of their mouths called the vomeronasal (or Jacobson's) organ. When a cat wrinkles its muzzle, lowers its chin, and lets its tongue hang a bit, it is opening the passage to the vomeronasal. This is called "gaping", "sneering", "snake mouth", or "flehming". Gaping is the equivalent of the Flehmen response in other animals, such as dogs, horses and big cats.
Brain-to-body mass ratio
Dolphins have the highest brain-to-body weight ratio of all cetaceans. Monitor lizards, tegus and anoles and some tortoise species have the largest among reptiles. Among birds, the highest brain-to-body ratios are found among parrots, crows, magpies, jays and ravens. Among amphibians, the studies are still limited. Either octopuses or jumping spiders have some of the highest for an invertebrate, although some ant species have 14%-15% of their mass in their brains, the highest value known for any animal. Sharks have one of the highest for fish alongside manta rays (although the electrogenic elephantfish has a ratio nearly 80 times higher - about 1/32, which is slightly higher than that for humans). Treeshrews have a higher brain to body mass ratio than any other mammal, including humans. Shrews hold about 10% of their body mass in their brain.
Neuroscience and intelligence
Another theory of brain size in vertebrates is that it may relate to social rather than mechanical skill. Cortical size relates directly to a pairbonding life style and among primates cerebral cortex size varies directly with the demands of living in a large complex social network. Compared to other mammals, primates have significantly larger brain size. Additionally, most primates are found to be polygynandrous, having many social relationships with others. Although inconclusive, some studies have shown that this polygnandrous statue correlates to brain size.
Cat cognitive support diets
Recommended DHA and EPA concentrations have not been yet determined for cats in present day. According to AAFCO Dog and Cat Food Nutrient Profiles (2014), DHA and EPA the minimum amount for the growth and reproduction in cat food is 0.0012% on a dry matter basis or 0.03g per 1000 kcal ME per day. Alpha-linolenic acid, was recommended at 0.02% on a dry matter basis and 0.05g per 1000 kcal ME per day.
Bambiraptor
"Bambiraptor" had a brain size in the lower range of modern birds. Because of its enlarged cerebellum, which may indicate higher agility and higher intelligence than other dromaeosaurs, David A. Burnham has hypothesized that "Bambiraptor feinbergi" may have been arboreal. Life in the trees may have required evolutionary pressure that resulted in a larger brain. Burnham also offers an alternative hypothesis that a larger brain could be selected for as a result of hunting more agile prey items such as lizards and mammals. The "Bambiraptor" holotype had with 14 cm³ the largest brain for its size of any dinosaur yet discovered, although the brain size may be due to its age, because juvenile animals tend to have larger brain-to-body ratios compared to adults.
Flat-headed cat
The flat-headed cat is distinguished at once by the extreme depression of the skull, which extends along the nose to the extremity of the muzzle, the sides of which are laterally distended. The general habit of body is slender, and the extremities are delicate and lengthened. The head itself is more lengthened and cylindrical than in the domestic cat. The distance between the eyes and the ears is comparatively great. The cylindrical form and lateral contraction of the head is contrasted by an unusual length of the teeth. The canine teeth are nearly as long as in an individual of double its size.
Snowshoe cat
The ear size ranges from medium to medium-large with slightly rounded tips. The head may be triangular, however can be an "applehead" shape with a traditional cat look. The short-haired coat consists of solid and white patterns. Points (ears, tail, face-mask and sometimes legs) are solid black-based colors. White patterns vary, typically falling along the face, chest, stomach, and paws. The body is an even coloration, subtle shading to point color on back, shoulders and hips; toning to a lighter shade near chest and stomach. Paw pads may be white, point color, flesh tone, or mottled. Their color will darken with age, even to the point of turning a chocolate brown shade. In purebreds, the eyes are always blue. The tail is medium-sized. Snowshoe cats come in blue, lilac, lynx, fawn, chocolate, and seal points. The Snowshoe is a medium-large cat and longer length wise than many cats, with many males reaching 14  lbs or more.
Felis
The genus includes the domestic cat. The smallest "Felis" species is the black-footed cat with a head and body length from . The largest is the jungle cat with a head and body length from . 
"Felis" species inhabit a wide range of different habitats, from swampland to desert, and generally hunt small rodents, birds and other small animals, depending on their local environment. The worldwide introduction of the domestic cat also made it common to urban landscapes around the globe.
Human brain
As a primate brain, the human brain has a much larger cerebral cortex, in proportion to body size, than most mammals, and a highly developed visual system.
Ardipithecus
"Ardipithecus ramidus" had a small brain, measuring between 300 and 350 cm. This is slightly smaller than a modern bonobo or female common chimpanzee brain, but much smaller than the brain of australopithecines like Lucy (~400 to 550 cm) and roughly 20% the size of the modern "Homo sapiens" brain. Like common chimpanzees, "A. ramidus" was much more prognathic than modern humans.
Short-beaked echidna
The short-beaked echidna has the largest prefrontal cortex relative to body size of any mammal, taking up 50% of the volume in comparison to 29% for humans. This part of the brain in humans is thought to be used for planning and analytical behaviour, leading to debate as to whether the echidna has reasoning and strategising ability. Experiments in a simple maze and with a test on opening a trap door to access food, and the echidna's ability to remember what it has learnt for over a month, has led scientists to conclude its learning ability is similar to that of a cat or a rat.
Sand cat
The sand cat's fur is of a pale, sandy, light brownish-yellow color. Markings vary between individuals: some have neither spots nor stripes, some are faintly spotted, some have both spots and stripes. There are dark brown to blackish bars on the limbs, and the tail has a black tip with two or three dark rings alternating with buff bands. The head is sandy brown, whereas the lower and upper lips, chin, throat, and belly are white. Some individuals have a yellowish throat. The large, greenish-yellow eyes are ringed with white, and the nose is blackish. The lower part of the face is whitish, and a faint reddish line runs from the outer corner of each eye across the cheeks. The cat's whiskers are white and up to long.
The sand cat is a small cat, characterized by a flat, wide head, short legs, and a relatively long tail of . It stands at the shoulder and weighs . The head-and-body length ranges from . The long ears are set low, giving a broad, flat appearance to the head. The ears are tawny at the base and tipped with black, and more pointed than those of the Pallas's cat ("Otocolobus manul").
Chato Murciano
Along with its short nose, the breed usually has a black or white color and has small sized heads. Generally the head Chato Murciano can grow up to 28.5 cm long and 20 cm wide after reaching 12 years of age. This is only a 2–4 cm growth from when it is one year old. On its head, the snout increases size up to 10.5 cm but then decreases to about 9.5 cm when the pig reaches twelve years of age. Pigs at about 3.5 years or 12 years have their eyes separated from each other at about 16 cm where at 1 year, they are separated by 12.5 cm.
Brain size
When the mammalian brain increases in size, not all parts increase at the same rate. In particular, the larger the brain of a species, the greater the fraction taken up by the cortex. Thus, in the species with the largest brains, most of their volume is filled with cortex: this applies not only to humans, but also to animals such as dolphins, whales or elephants.
Cat intelligence
The number of cortical neurons contained in the brain of the cat is reported to be 763 million. Area 17 of the visual cortex was found to contain about 51,400 neurons per mm. Area 17 is the primary visual cortex.
Hans Thewissen
Thewissen’s current work involves counting neurons in bowhead and beluga whale brain samples, to assess brain function, in Utqiagvik—formerly Barrow—Alaska. Though the size of the brains of sperm whales and killer whales are larger than those of any other organism, including humans, a better measure of brain function is to determine how many neurons there are in the brain. Suzana Herculano-Houzel has developed a method of counting of neurons of human and other animals' brains and the relation between the cerebral cortex area and thickness and number of cortical folds. Humans and other primates pack about twice the number of neurons in a cubed inch of brain as most other mammals.
Craniometry
Based on craniometry data, Morton claimed in "Crania Americana" that the Caucasians had the biggest brains, averaging 87 cubic inches, Indians were in the middle with an average of 82 cubic inches and Negroes had the smallest brains with an average of 78 cubic inches.
Elephant cognition
Elephants also have a very large and highly convoluted hippocampus, a brain structure in the limbic system that is much bigger than that of any human, primate or cetacean. The hippocampus of an elephant takes up about 0.7% of the central structures of the brain, comparable to 0.5% for humans and with 0.1% in Risso's dolphins and 0.05% in bottlenose dolphins.
Catopithecus
CGM 42222 is the specimen in which the outline of the braincase was best preserved. After adjusting for potential distortion caused by crushing, a brain model was prepared that determining the approximate volume of the brain of CGM 42222 to be 3.1 cm ± 10%.4 Using the estimations of brain volume and body weight an encephalization quotient (EQ) was calculated that showed the brain volume to body size ratio of C. browni is small compared to extant anthropoids of similar weight.
Scientific racism
In Morton's "Crania Americana", his claims were based on Craniometry data, that the Caucasians had the biggest brains, averaging 87 cubic inches, Native Americans were in the middle with an average of 82 cubic inches and Negroes had the smallest brains with an average of 78 cubic inches.
Cat intelligence
According to researchers at Tufts University School of Veterinary Medicine, the physical structure of the brains of humans and cats is very similar. The human brain and the cat brain both have cerebral cortices with similar lobes.
Brain size
Apes
Common opossum
The common opossum is similar in size to a house cat. The fur of the opossum is actually yellow in the under-fur, but is hidden by the longer black guard-hairs that cover it, while the tail, fingers, and face are lighter "with the tail being without fur, somewhat similar to a giant rat tail." It can measure nearly 20 inches long. It has large ears that are usually black, and its face is usually a pale peach in color, with black whiskers and eyes that reflect reddish in light. With a body length of nearly a foot, and a tail that can reach almost two feet, the common opossum is one of the larger members of its family. An adult can weigh more than three pounds.
Cat
Cats are known for spending considerable amounts of time licking their coats to keep them clean. The cat's tongue has backwards-facing spines about 500 μm long, which are called papillae. These contain keratin which makes them rigid so the papillae act like a hairbrush. Some cats, particularly longhaired cats, occasionally regurgitate hairballs of fur that have collected in their stomachs from grooming. These clumps of fur are usually sausage-shaped and about long. Hairballs can be prevented with remedies that ease elimination of the hair through the gut, as well as regular grooming of the coat with a comb or stiff brush.
Pteropus
The megabats, including flying foxes, have the greatest encephalization quotient (brain size relative to body size) of any bat family at 1.20. 
This value is equivalent to that of domestic dogs.
Flying foxes display behaviors that indicate a reliance on long-term information storage.
Though they have wide-ranging movements and cover thousands of square kilometers annually, they are consistently able to locate the same resource patches and roosts.
They will visit these resource patches consistently in a strategy known as trap-lining.
They can also be conditioned to perform behaviors, such as one study where spectacled flying foxes were trained to pull a lever using juice as a reinforcement.
In a follow-up to the initial study, individuals who had learned to pull the lever to receive juice still did so 3.5 years later.
Black-footed cat
The black-footed cat is the smallest wild cat in Africa and rivals the rusty-spotted cat as the world's smallest wild cat. Males reach a head-to-body length of with tails long. Females are smaller with a maximum head-to-body-length of and tails long.
Adult resident males weigh on average and a maximum of . Adult resident females weigh on average and a maximum of .
The shoulder height is about .
Encephalization quotient
Mean EQ for mammals is around 1, with carnivorans, cetaceans and primates above 1, and insectivores and herbivores below. This reflects two major trends. One is that brain matter is extremely costly in terms of energy needed to sustain it. Animals which live on relatively nutrient poor diets (plants, insects) have relatively little energy to spare for a large brain, while animals living from energy-rich food (meat, fish, fruit) can grow larger brains. The other factor is the brain power needed to catch food. Carnivores generally need to find and kill their prey, which presumably requires more cognitive power than browsing or grazing. The brain size of a wolf is about 30% larger than a similarly sized domestic dog, again reflecting different needs in their respective way of life.
Human
The human species developed a much larger brain than that of other primates—typically in modern humans, over twice the size of that of a chimpanzee or gorilla. The pattern of encephalization started with "Homo habilis" which at approximately had a brain slightly larger than chimpanzees, and continued with "Homo erectus" (), and reached a maximum in Neanderthals with an average size of , larger even than "Homo sapiens" (but less encephalized). The pattern of human postnatal brain growth differs from that of other apes (heterochrony), and allows for extended periods of social learning and language acquisition in juvenile humans. However, the differences between the structure of human brains and those of other apes may be even more significant than differences in size. The increase in volume over time has affected different areas within the brain unequally—the temporal lobes, which contain centers for language processing have increased disproportionately, as has the prefrontal cortex which has been related to complex decision making and moderating social behavior. Encephalization has been tied to an increasing emphasis on meat in the diet, or with the development of cooking, and it has been proposed that intelligence increased as a response to an increased necessity for solving social problems as human society became more complex.
Western quoll
The western quoll is about the size of a domestic cat. It is coloured a rufous brown and has 40–70 white spots on its back with a creamy white underside. Its spots actually help diminish its outline from the moon at night when hunting. It has five toes on its hind feet and granular pads. The head and body are about 36 cm to 46 cm in length, and the tail is around 22 cm to 30 cm. With large eyes and pointed ears, it is well adapted for nocturnal life. The black brush on its tail extends from halfway down to the tip. Males typically weigh around 1.3 kg, and females 0.9 kg. The longest they are likely to live is four years.
Cat intelligence
The domestic cat brain also contains the hippocampus, amygdala, frontal lobes (which comprise 3 to 3.5% of the total brain in cats compared to about 25% in humans), corpus callosum, anterior commissure, pineal gland, caudate nucleus, septal nuclei and midbrain.
Tortoise
The brain of a tortoise is extremely small. The tortoises, from Central and South America, do not have an area in the brain called the hippocampus, which relates to emotion, learning, memory and spatial navigation. Studies have shown that red-footed tortoises may rely on an area of the brain called the medial cortex, an area that humans use for actions such as decision making.
King-Size Canary
The bird is emptied from the sack, to be revealed as scrawny and little. The bird tells the cat, "Well, I've been sick..." Disgusted with the tiny creature at first but still desperate, the cat gets a (literal) brainstorm when he sees a bottle of Jumbo-Gro plant growth formula on the shelf. Quickly he pours some of the formula into the bird and sure enough, the canary grows rapidly in size. But before the cat can take a bite, the bird is already over 10 feet tall. The canary takes advantage of his new height and beats up on the cat. The cat turns the tables on the bird and drinks the Jumbo-Gro formula himself, doubling in size until he is much bigger than the bird. He tosses the potion out of the window only for it to land in the bulldog's mouth. While the now giant-sized cat chases the slightly smaller canary through the side of the house, the bulldog guzzles down the formula. After a quick run around the block, the cat and canary wind up back outside of the house, where a now gigantic bulldog appears before them. The cat runs away in fear as the bulldog tosses the bottle of plant growth food down the chimney, where it rolls out of the fireplace and straight to the mouse inside the house. The dog leaps over the house and chases the cat into the city.
Elephant cognition
The encephalization quotient (EQ) (the size of the brain relative to body size) of elephants ranges from 1.13 to 2.36. The average EQ is 2.14 for Asian elephants, and 1.67 for African, with the overall average being 1.88. In comparison to other animals, the La Plata dolphin has an EQ of 1.67; the Ganges River dolphin of 1.55; the orca of 2.57; the bottlenose dolphin of 4.14; and the tucuxi dolphin of 4.56; chimpanzees at 2.49; dogs at 1.17, cats at 1.00; and mice at 0.50. Humans have an EQ of 7.44.
Felidae
In the great majority of species, the tail is between a third and a half of the body length, although with some exceptions, like the "Lynx" species and margay.
Cat species vary greatly in body and skull sizes, and weights:
Southern grasshopper mouse
Relative brain size tends to vary with food preferences. Brain size is usually smallest in folivores, larger in both granivores and insectivores, and largest in generalists. Measurements of cranial volume of museum specimens of southern grasshopper mouse have shown that on average, females were heavier and longer than males, but their cranial volume was about 3% less than that of males. However, this was not a significant difference. This pattern of brain-body relationship can also be seen in northern grasshopper mice. Moreover, the tail length of southern grasshopper mice made up an average of 33.9% of its body length. Their tail length measures an average of 4.58 ± 0.36 cm in females, and 4.50 ± 0.39 cm in males. Average tail length does not vary greatly between the sexes.
Amphimachairodus
For felines, this skull is rather long, but rivaled by the skulls of the two largest species of extant cats: the lion and tiger. When compared with the skull of a regular lion, it is long and very narrow, particularly in the muzzle and width of the zygomatic arches. Its sagittal crest is well pronounced. Compared with other machairodonts, the canines are stout and capable of large amounts of stress. This characteristic is slightly remodeled in females, whose canines are slimmer and generally longer. Compared with females, the orbit of males are smaller, muzzles larger, the anterior-most portion of the nasal bones generally flare upwards slightly, and the downward slope of the dorsal edge of the skull in front of the orbit is not as pronounced, producing a straighter profile. Compared with the most well known machairodont "Smilodon", commonly referred to as the "saber-toothed cat", the canines are much shorter, the facial portion again is much longer, and the teeth not reduced so far in number. Several machairodonts, namely "Megantereon", bear flanges on the mandible, which are very reduced in "A. giganteus" though characteristics of the mandible associated with the flanges are present, particularly the lateral flattening of the anterior portion of the mandible, creating a cross section more square than semi-circular. The dental formula for this specimen is .
Sex differences in psychology
Structurally adult male brains are on average 11–12% heavier and 10% bigger than female brains. Despite this, because of relative difference in body size the brain-to-body mass ratio does not differ between the sexes.Other studies have stated bigger male brain size can only be partly accounted by body size. Researchers also found greater cortical thickness and cortical complexity in females and greater female cortical surface area after adjusting for brain volumes. Given that cortical complexity and cortical features are positively correlated with intelligence, researchers postulated that these differences might have evolved for females to compensate for smaller brain size and equalize overall cognitive abilities with males. Women have a greater developed neuropil or the space between neurons, which contains synapses, dendrites and axons and the cortex has neurons packed more closely together in the temporal and prefrontal cortex. Females also have greater cortical thickness in posterior temporal and inferior parietal regions compared to males independent of differences in brain or body size.
Fetal EEG
The youngest fetus that Borkowski and Bernstine studied was between 43 and 45 days post-conception – only 16mm long. At 45 days after conception, the brain is bent forward and is almost as large as the entire body of the fetus, allowing for these deep recordings. The 45-day old fetus’s electrical signals resembled the “discontinuous” patterns observed in healthy newborns, premature infants, and fetuses in the last trimester of pregnancy. The doctors also observed patterns that resembled “sleep spindles” in adults. The scientists continued recording until they consistently observed patterns of brain death, since the fetuses could not survive outside the uterus.
Brain size
Not all investigators are happy with the amount of attention that has been paid to brain size. Roth and Dicke, for example, have argued that factors other than size are more highly correlated with intelligence, such as the number of cortical neurons and the speed of their connections. Moreover, they point out that intelligence depends not just on the amount of brain tissue, but on the details of how it is structured. It is also well known that crows, ravens, and grey parrots are quite intelligent even though they have small brains.
Cat senses
Cats have a "tapetum lucidum", which is a reflective layer behind the retina that sends light that passes through the retina back into the eye. While this improves the ability to see in darkness and enables cats to see using roughly one-sixth the amount of light that people need, it appears to reduce net visual acuity, thus detracting when light is abundant. A cat's visual acuity is anywhere from 20/100 to 20/200, which means a cat has to be at 20 metres to see what an average human can see at 100 or 200 metres. Cats seem to be nearsighted, which means they can't see far objects as well. The ability to see close objects would be well-suited for hunting and capturing prey. In very bright light, the slit-like pupil closes very narrowly over the eye, reducing the amount of light on the sensitive retina, and improving depth of field. Big cats have pupils that contract to a round point. The tapetum and other mechanisms give the cat a minimum light detection threshold up to seven times lower than that of humans. Variation in color of cats' eyes in flash photographs is largely due to the reflection of the flash by the tapetum.
Giraffatitan
"Giraffatitan"s brain measured about 300 cubic centimetres, which, like those of other sauropods, was small compared to its massive body size. A 2009 study calculated its Encephalization Quotient (a rough estimate of possible intelligence) at a low 0.62 or 0.79, depending on the size estimate used. Like other sauropods, "Giraffatitan" has a sacral enlargement above the hip which some older sources misleadingly referred to as a "second brain". However, glycogen bodies are a more likely explanation.
Hearing range
Cats have excellent hearing and can detect an extremely broad range of frequencies. They can hear higher-pitched sounds than humans or most dogs, detecting frequencies from 55 Hz up to 79 kHz. Cats do not use this ability to hear ultrasound for communication but it is probably important in hunting, since many species of rodents make ultrasonic calls. Cat hearing is also extremely sensitive and is among the best of any mammal, being most acute in the range of 500 Hz to 32 kHz. This sensitivity is further enhanced by the cat's large movable outer ears (their "pinnae"), which both amplify sounds and help a cat sense the direction from which a noise is coming.
The hearing ability of a dog is dependent on breed and age, though the range of hearing is usually around 67 Hz to 45 kHz. As with humans, some dog breeds' hearing ranges narrow with age, such as the German shepherd and miniature poodle. When dogs hear a sound, they will move their ears towards it in order to maximise reception. In order to achieve this, the ears of a dog are controlled by at least 18 muscles, which allow the ears to tilt and rotate. The ear's shape also allows the sound to be heard more accurately. Many breeds often have upright and curved ears, which direct and amplify sounds.
Koala
The koala has one of the smallest brains in proportion to body weight of any mammal, being 60% smaller than that of a typical diprotodont, weighing only . The brain's surface is fairly smooth, typical for a "primitive" animal. It occupies only 61% of the cranial cavity and is pressed against the inside surface by cerebrospinal fluid. The function of this relatively large amount of fluid is not known, although one possibility is that it acts as a shock absorber, cushioning the brain if the animal falls from a tree. The koala's small brain size may be an adaptation to the energy restrictions imposed by its diet, which is insufficient to sustain a larger brain. Because of its small brain, the koala has a limited ability to perform complex, unfamiliar behaviours. For example, when presented with plucked leaves on a flat surface, the animal cannot adapt to the change in its normal feeding routine and will not eat the leaves. The koala's olfactory senses are normal, and it is known to sniff the oils of individual branchlets to assess their edibility. Its nose is fairly large and covered in leathery skin. Its round ears provide it with good hearing, and it has a well-developed middle ear. A koala's vision is not well developed, and its relatively small eyes are unusual among marsupials in that the pupils have vertical slits. Koalas make use of a novel vocal organ to produce low-pitched sounds (see social spacing, below). Unlike typical mammalian vocal cords, which are folds in the larynx, these organs are placed in the velum (soft palate) and are called velar vocal cords.
Evolution of nervous systems
There has been a gradual increase in brain volume as the ancestors of modern humans progressed along the human timeline of evolution (see Homininae), starting from about 600 cm in "Homo habilis" up to 1736 cm in "Homo neanderthalensis". Thus, in general there is a correlation between brain volume and intelligence. However, modern "Homo sapiens" have a smaller brain volume (brain size 1250 cm) than neanderthals; women have a brain volume slightly smaller than men, and the Flores hominids ("Homo floresiensis"), nicknamed "hobbits", had a cranial capacity of about 380 cm, about a third of the "Homo erectus" average and considered small for a chimpanzee. It is proposed that they evolved from "H. erectus" as a case of insular dwarfism. In spite of their threefold smaller brain there is evidence that "H. floresiensis" used fire and made stone tools as sophisticated as those of their proposed ancestor, "H. erectus". Iain Davidson summarizes the opposite evolutionary constraints on human brain size as "As large as you need and as small as you can".
Boiga siamensis
The Siamese cat snake resembles the dog-toothed snake but it occupies a different geographical range. It is a large snake, reaching almost 2 m (6 1⁄2 ft) in total length. Colours are greyish-brown with black crossbars that are most distinct interiorly. The head is dark brown with a dark streak from behind the eye to the first body crossbar that is broken just beyond the last supralabial. The chin and throat are white, the ventrals white to light brown
Caspian tiger
The Caspian tiger ranked among the largest cats that ever existed. Males had a body length of and weighed ; females measured in head-to-body and weighed . Maximum skull length in males was , while that of females was . Its occiput was broader than of the Bengal tiger.
Edmontosaurus
The brain of "Edmontosaurus" has been described in several papers and abstracts through the use of endocasts of the cavity where the brain had been. "E. annectens" and "E. regalis", as well as specimens not identified to species, have been studied in this way. The brain was not particularly large for an animal the size of "Edmontosaurus". The space holding it was only about a quarter of the length of the skull, and various endocasts have been measured as displacing to , which does not take into account that the brain may have occupied as little as 50% of the space of the endocast, the rest of the space being taken up by the dura mater surrounding the brain. For example, the brain of the specimen with the 374 millilitre endocast is estimated to have had a volume of . The brain was an elongate structure, and as with other non-mammals, there would have been no neocortex. Like "Stegosaurus", the neural canal was expanded in the hips, but not to the same degree: the endosacral space of "Stegosaurus" had 20 times the volume of its endocranial cast, whereas the endosacral space of "Edmontosaurus" was only 2.59 times larger in volume.
Lemur
A few lemurs have been noted to have relatively large brains. The extinct "Hadropithecus" was as large as a large male baboon and had a comparably sized brain, giving it the largest brain size relative to body size among all prosimians. The aye-aye also has a large brain-to-body ratio, which may indicate a higher level of intelligence. However, despite having a built-in tool in the form of its thin, elongated middle finger, which it uses to fish for insect grubs, the aye-aye has tested poorly in the use of extraneous tools.
Bobcat
The adult bobcat is long from the head to the base of the tail, averaging ; the stubby tail adds and its "bobbed" appearance gives the species its name. An adult stands about at the shoulders. Adult males can range in weight from , with an average of ; females at , with an average of . The largest bobcat accurately measured on record weighed , although unverified reports have them reaching . Furthermore, a June 20, 2012 report of a New Hampshire roadkill specimen listed the animal's weight at . The largest-bodied bobcats are from eastern Canada and northern New England of the subspecies "L. r. gigas", while the smallest are from the southeastern subspecies "L. r. floridanus", particularly those in the southern Appalachians. The bobcat is muscular, and its hind legs are longer than its front legs, giving it a bobbing gait. At birth, it weighs and is about in length. By its first birthday, it weighs about .
Cat body-type mutation
Four ears – a recessive mutation that produced four pinnae or ear flaps (the additional pinnae did not lead to additional ear canals and organs of hearing). In a group of four-eared cats studied in 1957, in addition to duplicated ears, the eyes were reduced in size, the jaw was slightly undershot and the cats were relatively inactive and lethargic. Researchers believed that the functioning of the brain was affected. Breeding data indicated it was most often lethal with kittens dying in utero. The majority of recently reported four-eared cats have been healthy with various ear configurations suggesting other genes were involved or developmental abnormalities rather than hereditary factors.
Cat intelligence
Just as in humans, advancing age may affect memory in cats. Some cats may experience a weakening of both learning ability and memory that affects them adversely in ways similar to those occurring in poorly aging humans. A slowing of function is normal, and this includes memory. Aging may affect memory by changing the way their brain stores information and by making it harder to recall stored information. Cats lose brain cells as they age, just as humans do. The older the cat, the more these changes can affect its memory. There have been no studies done on the memories of aging cats, but there is some speculation that, just like people, short-term memory is more affected by aging. In one test of where to find food, cats' short-term memory lasted about 16 hours.
Deception in animals
Tactical deception has been used as a measure of advanced social cognition as it relates to brain function. Primates have larger brains, relative to body size, than in any other mammal except for dolphins, and this size difference is mainly due to an enlarged neocortex. Research has suggested that the evolution of the primate brain is selected-for in highly social species. One study used 18 species with varying brain volumes (three strepsirrhines, four New World monkeys, seven Old World monkeys, and four ape species). The study used the frequency of tactical deception as a measure of social cognition, and it found a strong correlation between the use of social deception and size of the neocortex.
Samuel George Morton
Morton claimed in his "Crania Americana" that the Caucasians had the biggest brains, averaging 87 cubic inches (1,426 cc), Indians were in the middle with an average of 82 cubic inches (1,344 cc) and Negroes had the smallest brains with an average of 78 cubic inches (1,278 cc). Morton believed that the skulls of each race were so different that a wise creator from the beginning had created each race and positioned them in separate homelands to dwell in.
Jungle cat
The jungle cat is a medium-sized, long-legged cat, and the largest of the extant "Felis" species. The head-and-body length is typically between . This cat stands nearly at shoulder and weighs . Its body size decreases from west (Israel) to east (India); this was attributed to greater competition from small cats in the east; body size shows a similar decrease from the northern latitudes toward the tropics. Sexually dimorphic, females tend to be smaller and lighter than males. The face is long and narrow, with a white muzzle. The large, pointed ears, in length and reddish brown on the back, are set close together; a small tuft of black hairs, nearly long, emerges from the tip of both ears. The eyes have yellow irides and elliptical pupils; white lines can be seen around the eye. Dark lines run from the corner of the eyes down the sides of the nose and a dark patch marks the nose. The skull is fairly broad in the region of the zygomatic arch; hence the head of this cat appears relatively rounder.
Baleen whale
Baleen whales have a relatively small brain compared to their body mass. Like other mammals, their brain has a large, folded cerebrum, the part of the brain responsible for memory and processing sensory information. Their cerebrum only makes up about 68% of their brain's weight, as opposed to human's 83%. The cerebellum, the part of the brain responsible for balance and coordination, makes up 18% of their brain's weight, compared to 10% in humans, which is probably due to the great degree of control necessary for constantly swimming. Necropsies on the brains of gray whales revealed iron oxide particles, which may allow them to find magnetic north like a compass.
History of anthropometry
Several studies have demonstrated correlations between race and brain size, with varying results. In some studies, Caucasians were reported to have larger brains than other racial groups, whereas in recent studies and reanalysis of previous studies, East Asians were reported as having larger brains and skulls. More common among the studies was the report that Africans had smaller skulls than either Caucasians or East Asians. Criticisms have been raised against a number of these studies regarding questionable methods.
In "Crania Americana" Morton claimed that Caucasians had the biggest brains, averaging 87 cubic inches, Indians were in the middle with an average of 82 cubic inches and Negroes had the smallest brains with an average of 78 cubic inches. In 1873 Paul Broca (1824–1880) found the same pattern described by Samuel Morton's "Crania Americana" by weighing brains at autopsy. Other historical studies alleging a Black-White difference in brain size include Bean (1906), Mall, (1909), Pearl, (1934) and Vint (1934). But in Germany Rudolf Virchow's study led him to denounce "Nordic mysticism" in the 1885 Anthropology Congress in Karlsruhe. Josef Kollmann, a collaborator of Virchow, stated in the same congress that the people of Europe, be them German, Italian, English or French, belonged to a "mixture of various races," furthermore declaring that the "results of craniology" led to "struggle against any theory concerning the superiority of this or that European race". Virchow later rejected measure of skulls as legitimate means of taxonomy. Paul Kretschmer quoted an 1892 discussion with him concerning these criticisms, also citing Aurel von Törok's 1895 work, who basically proclaimed the failure of craniometry.
Whiskers
Anecdotally, it is often stated that cats use their whiskers to gauge whether an opening is wide enough for their body to pass through. This is sometimes supported by the statement that the whiskers of individual cats extend out to about the same width as the cat's body, but at least two informal reports indicate that whisker length is genetically determined and does not vary as the cat grows thinner or fatter. In the laboratory, rats are able to accurately (within 5-10%) discriminate the size of an opening, so it seems likely that cats can use their whiskers for this purpose. However, reports of cats, particularly kittens, with their heads firmly stuck in some discarded receptacle are commonplace indicating that if a cat has this information available, it doesn't always make best use of it.
Dragons (Dragon Prince)
In 719 Feylin had the opportunity to dissect a dragonsire. Sioned and Maarken aided her study using their Sunrunner memory and Maarken also drew careful renderings of bone, organs, and muscles. The dissection revealed that a dragon's brain is about double the size of a human one, but without as many wrinkles. The back portion of the brain is significantly larger than the front portion and the whole thing is a grayish color. Eyes, tongue, teeth, nasal cavity, stomach, lungs, heart, chest cavity, wings, and legs were also all cataloged, measured, and drawn.
Cerebral cortex
The cerebral cortex is folded in a way that allows a large surface area of neural tissue to fit within the confines of the neurocranium. When unfolded, each hemispheric cortex has a total surface area of about . The folding is inward away from the surface of the brain, and is also present on the medial surface of each hemisphere within the longitudinal fissure. Most mammals have a cerebral cortex that is convoluted with the peaks known as gyri and the troughs or grooves known as sulci. Some small mammals including some small rodents have smooth cerebral surfaces without gyrification.
Megaphragma mymaripenne
Uniquely, by the time "M. mymaripenne" reaches adulthood, 95% of its nervous cells have lost their nuclei. Only 339–372 nuclei are found throughout the central nervous system, of which 179–253 are found in the brain. The nervous system of the pupae of "M. mymaripenne" makes up 19% of its body mass, 11% of which is the brain. Unlike in adults, cells in the pupae have nuclei. Only in the final stage of development do these undergo lysis, which greatly reduces the volume of the nervous system. While the brains of pupae are 93,600 μm, those of the adults are only 52,200 μm. Accompanying this shrinkage of brain volume is a shrinking of the occipital area of the head, with the cuticle folding into helical spirals.
Brain size
The largest brain is that of the sperm whale, weighing about , and killer whales, weighing about . An elephant's brain weighs just over and a bottlenose dolphin's .
Brain size
Consistent with findings in adults, average cerebral volume is approximately 10% larger in boys than in girls. However, such differences should not be construed as imparting any sort of functional advantage or disadvantage; gross structural measures may not reflect functionally relevant factors such as neuronal connectivity and receptor density. Moreover, brain volumes, even in narrowly defined groups (e.g. children of the same age), may vary by as much as 50%. Young girls have, on average, larger hippocampi, whereas young boys have larger amygdalas.
Spectral bat
The spectral bat is the largest bat species native to the New World and the largest carnivorous bat in the world.
The wingspan typically ranges from .
Its forearm length is .
Its body length is and its mass is .
Its wings, though large in an absolute sense, are short relative to its body size.
The wings are wide, though, creating a large surface area.
Its wingtips are rounded and almost squarish.
The thumbs are long, at .
Each of its thumbs has a large, recurved claw that is grooved, similar to those of cats.
Its back fur is reddish-brown, long, and soft, while its belly fur is shorter and paler.
The forearm is furred on the half closer to the body, but naked on the half closer to the wrist and fingers.
Its molars are narrow with W-shaped crests.
While six of its molars have three cusps, as in many mammal species, the last upper molars are reduced to two cusps; they are much smaller than the other molars.
The talonids (crushing surfaces) of the molars are small relative to their trigonids (shearing surfaces).
The upper canine teeth are well-developed.
Its dental formula is for a total of 34 teeth.
Its skull is narrow and elongated with a pronounced sagittal crest. 
Overall, its skull resembles a miniature canid or bear skull.
Its nose-leaf is large, at in length.
There is no discernible tail, but the uropatagium (tail membrane) is long and broad.
Its legs are long, and the feet are composed of slender bones; each digit has a well-developed claw. The ears are large and rounded, at long.
Little brown bat
It has a relatively short snout and a gently sloped forehead.
It lacks a sagittal crest, which can be used to distinguish it from the Arizona myotis.
Its skull length is .
The braincase appears nearly circular though somewhat flattened when viewed from the back.
Its ears are long, while the tragi, or cartilaginous flaps that project in front of the ear openings, are long.
The tragi are blunt at the tips and considered of medium length for a mouse-eared bat.
Brain size
Studies on human brain size, largely based on participants of European ancestry, tend to find an average adult brain volume of 1260 cubic centimeters (cm) for men and 1130 cm for women. There is, however, substantial variation between individuals; one study of 46 adults, aged 22–49 years and of mainly European descent, found an average brain volume of 1273.6 cm for men, with a range of 1052.9 to 1498.5 cm, and 1131.1 cm for women, with a range of 974.9 to 1398.1 cm.