1. They can be allergic to you.

Does your cat cough frequently? You might be to blame. According to a 2005 study, feline asthma—which affects one in 200 cats—is on the rise thanks to human lifestyle. Since cats are more frequently being kept indoors, they’re more susceptible to inflammation of their airways caused by cigarette smoke, dusty houses, human dandruff, pollen and some kinds of cat litters. And in rare cases, humans can even transmit illnesses like the flu to their pets.

2. They’re not always affected by catnip.

In fact, half the cats in the world don't respond at all. Sensitivity to Nepeta cataria is inherited; cats with one catnip-sensitive parent have just a one-in-two chance of developing the sensitivity. If both parents have the sensitivity, however, the chances rise to three in four.

3. Cats can actually live with dogs.

Forget what Peter Venkman said about cats and dogs living together causing mass hysteria. A 2008 study by scientists at Tel Aviv University showed that if the animals are introduced while they're still young—six months for cats, and a year for dogs—they'll get along just fine.

4. Despite what you've read, your cats like it when you pet them.

You might have read about a study that suggested cats get anxious when you pet them. But that was a misinterpretation. “As a matter of fact, the majority of the cats enjoyed being stroked,” study co-author Rupert Palme of the Institute of Medical Biochemistry at the University of Veterinary Medicine, Vienna, explained later. “Only those animals that did not actually like to be stroked, but nevertheless allowed it, were stressed." So go ahead, pet away!

5. Cats have strategies for sharing space.

“We think we know about [domestic cats] because they are so familiar to us—living in our homes and being part of our families,” Professor Alan Wilson of Royal Veterinary College wrote on BBC.com. “In fact, we know less about some aspects of their behaviour than we do about many wild cats.” So in 2013, Wilson and a team of other scientists attached GPS trackers and cameras to 50 felines in Shamley Green, Surrey, for a BBC special. They found that the cats appeared to timeshare territory to avoid squabbles with other felines—though the cat-cams the kitties wore did capture a few fights.

6. A cat's brain is more complex than a dog's.

Sure, their brains are small, accounting for just 0.9 percent of their body mass. But according to Psychology Today, "the brains of cats have an amazing surface folding and a structure that is about 90 percent similar to ours." The cerebral cortex—the part of the brain that's responsible for cognitive information processing—is more complex in cats than in dogs, and cats have some 300 million neurons, as compared to 160 million in dogs. Some research does suggest that dogs are slightly smarter than cats, but cat owners might have a different opinion on that.

One more fun cat brain fact: The most sophisticated supercomputer in 2010 performed 83 times slower than a cat’s brain.

7. And their short-term memories are pretty good—under the right circumstances.

Short-term memories typically fade away in about a minute, but in a study published in Current Biology in 2007, scientists determined that cats' short-term memory of certain things lasts 10 minutes. The scientists tested it by stopping cats after their forelegs, but not their hindlegs, had cleared an obstacle. They distracted the cat with food and then waited to see how long the cats would remember having stepped over the obstacle. The cats remembered for about 10 minutes and would bring their hind legs up where they remembered an obstacle, even if it had been removed.

But when cats saw the obstacle and were distracted before they had a chance to step over it with their forelegs, they didn't remember the obstacle, indicating their visual memory is not so great. "We've found that the long-lasting memory for guiding hind legs over an obstacle requires stepping of the forelegs over the obstacle," researcher Keir Pearson of the University of Alberta in Canada said. "The main surprise was how short lasting the visual memory on its own was—just a few seconds when animals were stopped before their forelegs stepped over the obstacle."

8. Feral cats wander farther than free-roaming house cats.

A two-year study conducted by researchers at the University of Illinois-Champaign tracked 42 cats with radio collars and showed that the feral cats traveled more than free-roaming house cats. One of the ferals, a mixed-breed male, had the largest range of the wild cats with 1351 acres; the mean distance for house cats was a mere 4.9 acres.

That same study found that feral cats were also more active than house cats, which spent 97 percent of their time sleeping or engaged in low levels of activity. A mere 3 percent of their time was spent engaged in high levels of activity, like running or stalking prey, while the feral cats were active 14 percent of the time. "The un-owned cats have to find food to survive, and their activity is significantly greater than the owned cats throughout the day and throughout the year, especially in winter," said Jeff Horn, a former graduate student in the department of natural resources and environmental sciences, who conducted the study for his master's thesis. "These un-owned cats have to search harder to find food to create the (body) heat that they need to survive."

9. Some of their illnesses are similar to ours.

Cats are susceptible to more than 250 hereditary disorders, and many of them are similar to diseases that humans get. A genetic defect in a cat's DNA can cause retinitis pigmentosa, a disease that also affects 1 in 3500 Americans, and Feline Immunodeficiency Virus is a genetic relative of HIV. Felines even have their own form of Alzheimer’s Disease, and, like us, they can get fat—in fact, 55 percent (approximately 47 million) of American cats are overweight or obese.

10. Cat domestication began in China.

The Near Eastern Wildcat, native to Western Asia and Africa, is believed to be the primary ancestor of all domestic cats now living around the globe. Photo via Sonelle via Wikimedia Commons, used under Creative Commons license.

Scientists once believed that cats were domesticated in Ancient Egypt approximately 4000 years ago, but new research, published in 2013, shows that a breed of once-wild cats lived in close proximity to farmers in China some 5300 years ago. "Our data suggest that cats were attracted to ancient farming villages by small animals, such as rodents that were living on the grain that the farmers grew, ate and stored," says Fiona Marshall, study co-author and archaeology professor at Washington University in St. Louis. "Results of this study show that the village of Quanhucun was a source of food for the cats 5300 years ago, and the relationship between humans and cats was commensal, or advantageous for the cats. Even if these cats were not yet domesticated, our evidence confirms that they lived in close proximity to farmers, and that the relationship had mutual benefits."

11. Spots come from a particular gene.

Once, scientists didn't know how cats both big and small came by their distinctive blotched patterns. But a 2012 study pointed to a gene that scientists called Taqpep. Blotched cats had mutations on both copies of the gene, while striped cats did not. They also discovered that patterned markings are caused by variations in another gene, Edn3, and are expressed at high levels in the darkly colored hair cells. The scientists believe that early in a cat's development, the Taqpep gene establishes a periodic pattern for stripes or a spotted or blotched pattern by determining the level of Edn3 presented in each skin area.

12. They don't necessarily purr because they're happy.

Sure, cats purr when they appear to be content, but they also purr when they're giving birth, sick, nursing, wounded, or in a stressful situation. Scientists aren't quite sure why, but they do have some ideas. "Cats purr during both inhalation and exhalation with a consistent pattern and frequency between 25 and 150 Hertz," writes Leslie A. Lyons, an assistant professor at the School of Veterinary Medicine at the University of California, Davis, in Scientific American. "Various investigators have shown that sound frequencies in this range can improve bone density and promote healing...Because cats have adapted to conserve energy via long periods of rest and sleep, it is possible that purring is a low energy mechanism that stimulates muscles and bones without a lot of energy." Purring could help alleviate the dysplasia or osteoporotic conditions that are more common in dogs. So it's probably more plausible that cats use purring to communicate and as a source of self-healing.

13. They really can’t taste sweet things.

Cats aren't interested in sweet stuff because of a defect in the gene that codes for part of the mammalian sweet taste receptor. The receptor contains two protein subunits, T1R2 and T1R3, which are each coded for by a separate gene. The defect occurs on the T1R2 protein in domestic cats, as well as in cheetahs and tigers.

14. Disrupting their routines can make them act sick.

Even healthy cats can exhibit symptoms of illness—including going to the bathroom outside the litter box, vomiting, and a decreased appetite—if there's a change in their routines, according to study published in the January 1, 2011 issue of Journal of the American Veterinary Medical Association.

15. They are masters of lapping up liquid—and keeping their chins dry.

Unlike dogs, cats don't dip their tongues into liquid like ladles. Instead, it's only the surface of their tongues that touch the water. According to MIT News, "The smooth tip of the tongue barely touches the surface of the liquid before the cat draws its tongue back up. As it does so, a column of liquid forms between the moving tongue and the liquid’s surface. The cat then closes its mouth, pinching off the top of the column for a nice drink, while keeping its chin dry." Liquid adhesion causes liquid to stick to the cat's tongue, and the cat draws its tongue back so rapidly that inertia—the tendency of the moving liquid to continue following the tongue—overcomes the gravity that's pulling the water back down to the bowl. The cat snaps its mouth shut before gravity can overcome inertia.

16. They know exactly how to get what they want from their owners.

According to a 2009 study, they do it by mimicking babies crying. Cats in want of food will make an urgent cry or meowing sound in the 220 to 520-hertz frequency range while purring at a lower frequency. Babies also cry in this frequency range (usually between 300 and 600 hertz), and humans find it difficult to ignore.

Another annoying behavior that cats use to get their way is herding—darting between and rubbing on their owner's legs while they walk. “While cats are certainly not bred to be herding animals like some dogs, they do learn to direct human behavior—and motion—when their behavior is reinforced,” Dilara Goskel Parry, a cat behavior expert at Feline Minds, told The Dodo. "For example, ‘I do this, and my person is going to feed me.’ The darting and rubbing, which is called marking, likely starts as excitement, such as they feel right before feeding time. Many cat guardians reinforce these behaviors that they may find annoying simply by moving faster and feeding the cat.”

17. Even computers love cats.

Your cat loves to sit on your computer, probably because it's warm. But computers love cats, too: Google’s artificial “Brain,” a computer that contains 16,000 processors and can learn whatever it wants from the Internet, is really into cat videos.

18. There's a reason they drink water off their paws.

It's basically a matter of preference. Feline expert Mikel Delgado told The Dodo that "some cats may prefer licking their paws to drinking out of a water bowl if they don't like the shape of the water bowl. Cats are subject to ‘whisker stress’ where they may not like pressure on their whiskers while they eat or drink. It could also be because the water level isn't quite what they would like it to be—it’s usually too low.” Of course, they could also be doing it for a far simpler reason: Pawing the water creates ripples, which makes the water more interesting.

19. Males have barbed penises.

Hey, at one point, humans did, too. Scientists aren't entirely sure what cats need the 120-plus backward-pointing spines for, but they have a number of theories: That the spines encourage ovulation in the female; that they provide stimulation for the male; that they ensure his genes are passed along; or that they keep the penis in place during mating. Neuter your cat early, and he'll never develop those spines.

20. Cats spend a lot of time grooming.

OK, that fact on its own isn't very surprising. But just how much time cats spending grooming is. According to Cornell University's College of Veterinary Medicine, cats spend between 30 and 50 percent of their days cleaning themselves.

Self-cleaning has a number of benefits: It helps cool cats off, comforts them, stimulates circulation, and keeps them clean of odors that might attract predators. Sometimes, your cat might even groom you—that's her way of showing affection and marking you as one of her family group. Enjoy it!

All images courtesy of Thinkstock unless otherwise noted.