Cool Facts About Cats

By Eric M. Jones

“OWNERS OF DOGS WILL HAVE noticed that—if you provide them with food and water and shelter and affection—they will think you are god. Whereas owners of cats are compelled to realize that—if you provide them with food and water and shelter and affection—they draw the conclusion that they are gods.” ―Christopher Hitchens

My interpretation of this is a bit different. Dogs, lions, and most humans are pack hunters. There is an evolved part of the brain in such creatures that encourages them to follow the alpha leader. Even if the alpha leader is not around, the desire to follow remains strong. This complete obeisance to a leader can be interpreted as the desire for a “god.”

Most cats, badgers, bears, tigers and some humans are solitary hunters. Solitary hunters don’t have a highly-developed desire to follow any pack leader. In fact, they calculate that a pack would merely reduce their chance of finding game. Domestic cats are solitary hunters who have decided that humans are useful, because we can provide them with a warm dry place, food and shelter; but that’s about it. Dogs may think you are a god, but domestic cats are all hardcore atheists. Get over it.

Cats’ whiskers: The popular myth is that a cat’s whiskers are somehow used by the cat to measure if it can squeeze its body into tight places. Nothing could be further from the truth. Cats’ whiskers are an adaptation for hunting in very poor light. In utter darkness the cat can close its eyes to protect them and hunt only with its hearing, sense of smell, whiskers, teeth and claws. Cats have evolved to kill in a very particular way. The cat bites through the preys’ cervical spinal cord and therefore must know the exact orientation of the prey so that it can execute this precision maneuver. The whiskers encircle the prey to determine exactly how the victim is positioned for the fatal bite. There are infrared photos of cats with their whiskers neatly wrapped around a prey. If you trim off a cat’s whiskers ... there will be hell to pay. Some cats won’t eat and many more will exhibit neurotic behavior until the whiskers grow back. And the cat will never forgive you.

Like everything else on a cat, this system of whiskers is extremely complex. It consists of the twenty-four whiskers around the mouth in four sets on each upper lip, on each cheek, over the eyes, on the chin, on the cat’s inner wrists, and at the back of the legs. Each whisker has a deep connection with nerves leading to the barrel cortex of the cat’s brain which receives information from the whiskers in a manner similar to the visual cortex. This permits the cat to create a three-dimensional map of its surroundings while hunting in pitch darkness.

Odd Factoid: Tigers and lions have whiskers so stiff that they resemble ivory toothpicks. They can easily penetrate human flesh.

Cats’ dominant paw: Even though cats have been popular human pets for thousands of years, nobody seemed to have noticed that tomcats are virtually all left-pawed and pussycats are virtually all right-pawed. How this escaped human notice for all these millennia seems inexplicable, but cats don’t usually write or handle tools. Still, they have a dominant paw—as recently shown in tests where a piece of tuna fish was put into a glass tube deep enough so that the cat would use their dominant paw to try to get it (or so says the theory). Only a tiny percentage of cats of each sex seemed to show no paw-preference.

This is perhaps not as unusual as it seems at first glance. The correlation of sex and dominant-hand (or paw) occurs in humans too. A significant majority of humans are right-handed while the remaining fraction of lefty-humans are predominately males. Nobody really knows the basic human lefty-righty distribution because young human lefties are strongly pushed to become righties worldwide. In China, less than one percent of the population retains their left-handedness into adulthood. Chopsticks are always used right-handed, and Chinese written characters are extremely difficult to write left-handed. In Muslim cultures and most of Africa, the left hand is the “dirty” hand; used to wipe oneself. Allah forbid you should ever reach for food at the community table with your dirty left hand, bubella.

Cats’ taste buds are linked to their nose in a way that allows the cat to actually taste what they smell. This is why a cat licks its lips when it smells something. Cats and many animals have an auxiliary olfactory sense organ called the vomeronasal organ (VNO), or Jacobson’s organ. It is associated with both smell, taste, and pheromone detection, too.

Cats frequently exhibit a distinctive facial grimace called the flehmen response when encountering a scent that interests them. Flehmen is simply the German word for barring the upper teeth (hence it isn’t capitalized). This sends inhaled compounds directly to the Jacobson’s organ. The cat will lift its head, have a vacant stare, wrinkle its nose while lifting its lips, and stop breathing for a second or two. This sends odors to the VNO through ducts located behind the upper teeth.

It turns out that humans have a VNO too, but it is thought to “substantially” disappear during fetal development. There is some disagreement about this. There has long been a suspicion that the part of the adult human brain used to process VNO olfactory information is simply taken over for other brain functions and the VNO organ itself might work just fine. But experts say, "... based upon current evidence most in the field are skeptical about the likelihood of a functional VNO in adult human beings." However, the presence of a VNO in this writer would help explain some young-adult behavior for which I have no other conscionable excuse ... So who knows?

Scents are extremely important to cats. They have scent glands on their paws, mouth corners, near their anus, and their urine carries scents too. Their ability to detect odors—based on olfactory nerve-cell counts—is about fourteen times superior to human abilities. Furthermore, they are probably equivalent to, or better smellers than most dogs. (It might reduce crime quite a lot if K-9 cops used lions or tigers instead of dogs ... Hey! jus’ sayin’ ...)

Water: Cats can drink either fresh water, seawater or blood for moisture. Cats have evolved to eat only freshly killed meat and if so supplied, can live entirely without other sources of water.

Cats’ eyes: So why are cats’ pupils vertical slits? It turns out that almost all terrestrial predators who live close to the ground have eyes with vertical-slit pupils. All terrestrial grazers have eyes that are horizontal slits (or ovals), but when they put their heads down to graze; they too are vertical relative to the ground. All tree-dwelling animals like monkeys, and birds have round pupils. There are very few exceptions to this rule.

There are many technical articles that take a wild stab at explaining this, but I propose that eyes with vertically slit pupils work better in hunting environments that are composed predominantly of vertical standing elements like grasses. The less that these animals depend on grasses for hunting, or the taller they are, the more likely it is that their pupils are round. Hence, the dogs’ and lions’ rounder pupils. Smaller foxes, in fact, tend to have slit pupils, while large foxes have round pupils.

Cats have a reflective light-yellow-green layer behind the retina that sends light that passes through the retina back into the eye, giving the photoreceptors two swings at every live photon. While this tapetum lucidum improves the cats’ ability to see in dim light, it probably reduces daytime visual acuity somewhat. But the tapetum lucidum, and the huge f-number of the eyes give the cat an astonishing minimum-light-detection threshold up to seven times better than that of humans.

Cats’ night vision is far superior to that of its rodent prey, too. More than a century ago it was believed that the light reflected from a cats’ tapetum could be beamed at a prey like small searchlights to illuminate the prey in very low light conditions—a seriously amazing concept indeed—and one that should not be dismissed out of hand. The now-obsolete head mirror once typically worn by ENT doctors operated in a somewhat analogous way.

Unlike humans, cats do not need to blink their eyes to keep them lubricated with tears. Unblinking eyes are probably a great advantage when hunting.

Nobody understands why cats don’t get cat hair into their own eyes. There’s your next science fair project.

Cats’ play modes: For centuries humans have described how cats and their kittens exhibit play modes that seemed to copy the physical moves that will be useful for hunting in later life. Amongst these distinctive and instinctive moves are:

The Pounce. No mystery there. Mouse ... pounce. All living cat species except cheetahs pounce. Cheetahs, like dogs, run down their prey and can’t retract their claws. Cheetahs, the swiftest land animal, can run twenty kilometers per hour faster than a greyhound.

The Leap: No mystery there either. Not much flies out of tall grasses but birds and cats’ claws.

But the Sweep and Reverse was a puzzle for ... oh ... four thousand years until one day a wild cat was filmed fishing on the bank of a stream and it was seen to sweep a fish out of a stream and reverse to bite it.

Domestic cats have been known to dive into the ocean, to catch fish.

[This snowshoe Siamese cat named Pretty Good Kitty, at right, lost a couple of whiskers on her first mouse kill, but she learned quickly and now never loses whiskers.]

Polydactyl cats (those with as many as ten extra toes) are common in New England and the east coast of the United States. There are some in the British Isles, too—otherwise they are rare.

[Not a Yeti. Below left, this paw print in the snow is from a polydactyl cat.]

The first report of polydactyl cats appears to be from an article in the “American Naturalist,” 1873. Included in the report is a plausible explanation of how the cats carrying the defective gene were inbred in a household near Freehold, NJ, from a single polydactyl tomcat carried fifteen miles distant from Allentown, NJ, Most defective genes do not breed true. But these cats were able to pass on their defective polydactyl genes to their offspring. Legend has it that sailors from Boston then carried polydactyl cats on their ships to kill vermin. One seaman gave novelist Ernest Hemingway one as a gift from which he raised a colony of polydactyl cats that still exists today in Key West.

Cats’ colors and patterns: The various coat patterns of cats evolved to camouflage them in their natural surroundings. The more visually complicated the natural surroundings, the more complicated the camouflage. It is said that some cat patterns appear from overhead to be coiled snakes so as to discourage, or perhaps attract, aerial predators. These would then become prey. A tigers’ coat pattern is unique in that it goes all the way into their skin. That is, if you were foolhardy enough to shave a tiger it would look just about the same. What advantage this brings the tiger is unknown. Domestic cats are considerably influenced in their coat appearance by humans selecting human-pleasing patterns from the litter.

But many mysteries remain. Russian biologists discovered that Siamese kittens change color in response to ambient temperature. Siamese cats apparently carry albino genes that turn on only when the ambient temperature is above 37° C. If such kittens are raised in a very warm environment, they will stay creamy white and their coats won’t darken. Exactly how this odd fact was discovered is a puzzle. One supposes other strange gene-temperature links are yet to be discovered, unless PETA stops it.

The physiology of human brains is closer to cats’ brains than to dogs’ brains. Both humans and cats have identical regions in their brains that are thought to be responsible for emotion. Kittens’ mental abilities are astonishingly malleable and adjust to their surroundings. Kittens raised in rooms with only vertical stripes will develop into cats that cannot see horizontal surfaces like chair seats, counters or table tops. Kittens raised in a room with only horizontal stripes will grow into adult cats that cannot see vertical objects like chair legs and poles. This always seemed to me to fall under the category of “How to Torture Cats.”

Cats as human pets seem to have been a recent phenomenon. Compared to dogs, cats have not changed much during their few millennia of domestication. Dogs seem to have been domesticated in the earliest human hunter-gatherer tribes, over 40,000 years ago. Domestic cats are recent arrivals in comparison. There is only a single known example of cats being kept as pets by early man—a 9,500-year-old cat burial in Cyprus. Legend has it that Egyptians domesticated the cat, but more likely the Chinese did it. Cats as human companions probably arose as a natural response to protecting agricultural harvests from rodents.

The Greeks did not seem to have had many cats, and they were rare in ancient Rome, too.

Taxonomists have had considerable difficulty in classifying the cat family. Cat bones don’t always have distinct differences between species. Indeed, many species are more a matter of size and coat markings. One older scheme divided the cat family into Big Cats and Little Cats. This was not very helpful. The recent advent of mitochondrial-DNA analysis has cleared up much of the mystery of how cats evolved and how they are related.

The hypercarnivorean Felidae cat family comprises 37 to 41 (depending on how you count them) living species. The first identifiable cat showed up in Asia about 25 million years ago and spread across Asia and Africa. It evolved into three distinct Sub-Families—Machairodontinae, (now completely extinct) which included the “saber-toothed cats,” such as the well-known hyper-specialized Smilodon. Pantherinae—which includes panthers, tigers, lions, jaguars, and leopards; and Felinae—which includes cougars, cheetahs, lynxes, ocelots, and the domestic cat.

Much of the evolution of cats had to do with ice age sea levels in the Bering Strait rising and falling ... either preventing or allowing access between the Americas and Asia-Africa. About nine million years ago cats started appearing in the Americas, and over the millennia there were at least ten major periods of migration. Cats went back and forth and evolved in small pockets on the four continents (there were no ancient cats in Australia). The cheetah, for instance, belongs to a lineage that evolved in North America and migrated back across the Bering land bridge to Africa three million years ago.

The domestic cat—the most successful cat species of all—emerged some 6.2 million years ago, probably from North American cats that had trekked back across the Bering land bridge, and later, even concocted a brilliant plan to get human beings to feed it, pet it, and take care of its young.

And the name “pussycat?” “Cat” is an ancient name probably derived from the Late Egyptian čaute. This became the Latin cattus. The derivation of “pussy” is debatable but the name has long been associated with human females. It is, of course, a slang word for the female pudenda. As such it could be associated with the connotation of a cat being soft, warm, and fuzzy. Others suggest “psss” is a sound many cats respond to, since the sound is easy for them to hear. Variations of “puss” or something similar sounding seem universal in most cultures.

Nobody is quite sure how cats purr, or how they can read our minds, why the Pope says they consort with demons, why they steal the breath of babies in cribs, or even what their ultimate plan for conquest of the Internet universe might be. But, I suppose, more will be revealed.

Nerd Note: Jacob Rabinow, polymath and inventor-extraordinaire was once wondering how cats’ movements could be so graceful. He was interested in programming robot actuators to smooth their jerky motion and was puzzled that there did not seem to be a simple way to code smooth robot and machine motion unless everything was slowed down to a crawl. One night it occurred to him that graceful motion implied that the basic equation of motion, along with its first-, second-, and third-order derivatives—the distance, the velocity, the acceleration and the impulse (rate-of-change of acceleration)—simultaneously approached zero. Ah, the ultimate equation of grace in every cat movement ... 

Further Reading

“Cat Evolution,” Nicholas Wade, “New York Times,” January 6, 2006.
American Naturalist, “Malformations,” 1873 v7, p632.
“How Humans Created Cats,” “The Atlantic.”
“On the Tapetum Lucidum,” Medico-Chirurgical Transactions, 1886.
PETA: People for the Ethical Treatment of Animals.

Eric M. Jones is the Contributing Editor of “Perihelion.” He is an engineer, designer, consultant, and entrepreneur. His Internet business PerihelionDesign, builds and sells products, parts and materials to the home-built experimental aircraft community.