Why Do Cats Love to Knead?

iStock
iStock

If you're a cat lover, chances are your favorite feline has shown a penchant for kneading, and at some point has given you and/or a favorite piece of furniture a massage with his or her rhythmic paws. Colloquially called “making biscuits,” kneading is a common behavior among kittens and adult cats alike—but animal experts still aren't sure exactly why they do it.

Scientists have a few theories, some of which SciShow’s Hank Green outlined in this fascinating video. One theory is that your cat's kneading is an attempt to mark its territory—yes, even if that “territory” is you—with the scent glands in its paws. Another rationale is that kneading is a neotenic behavior, or a juvenile trait that sticks with cats into adulthood. Kittens knead their mother's belly to stimulate milk production—an act that’s nearly identical to that strange, Shiatsu-like practice it’s doing in your lap. (This could also explain why some adult cats also "suckle" the items they're kneading.)

Green does point out that domestic cats knead, whereas wild cats don’t, which raises the question: Why have only domestic felines retained this behavior? Green attributes this to the fact that house cats were selected over thousands of years for their friendlier, less aggressive traits, but says they've "probably also held on to some of their more social, baby-like behavior, just because it serves them well when they’re around people."

"I don’t know if you’ve heard this, but wildcats are not super social," Green jokes. "They don’t come up and cuddle, so much as try to eat your flesh. Felis silvestris, the ancestor of all domestic cats, is a solitary hunter that only socializes with members of its own species when it’s time to breed. So wildcats only developed social behaviors for two situations”—mating and caretaking behaviors between mother cats and their kittens.

“Unlike wild cats though, domesticated cats have a lot of social behaviors as adults, because they’re not wild loners anymore," Green adds. "They have us to cuddle with, con treats out of, and demand food from. So their innate tendencies for snuggling with mom and hitting on the lady cats are put to good use on us."

While occasionally painful or bothersome, kneading one’s owner is definitely a loving act on the part of the cat, a way of letting you know that it feels comfortable and safe with you. That said, don't sweat it if your cat isn’t big on the habit—or, conversely, worry that it kneads too much.

“Some cats are more needy and knead more than others,” Dr. Michael W. Fox, a veterinarian and author of the syndicated newspaper column "Animal Doctor,” advised one anxious reader who reported that her kitty had taken to kneading the family dog. “This behavior is exacerbated when a cat is weaned from its mother too soon. It’s an anxious cat’s way of seeking contact comfort.”

If you’re not a fan of kneading, it's futile to train your cat to cease a perfectly natural behavior. Instead, consider investing in a pair of nail clippers—and when you’ve finally had enough, gently push the cat away and enjoy the fleeting freedom of an empty lap.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

Why Does Humidity Make Us Feel Hotter?

Tomwang112/iStock via Getty Images
Tomwang112/iStock via Getty Images

With temperatures spiking around the country, we thought it might be a good time to answer some questions about the heat index—and why humidity makes us feel hotter.

Why does humidity make us feel hotter?

To answer that question, we need to talk about getting sweaty.

As you probably remember from your high school biology class, one of the ways our bodies cool themselves is by sweating. The sweat then evaporates from our skin, and it carries heat away from the body as it leaves.

Humidity throws a wrench in that system of evaporative cooling, though. As relative humidity increases, the evaporation of sweat from our skin slows down. Instead, the sweat just drips off of us, which leaves us with all of the stinkiness and none of the cooling effect. Thus, when the humidity spikes, our bodies effectively lose a key tool that could normally be used to cool us down.

What's relative about relative humidity?

We all know that humidity refers to the amount of water contained in the air. However, as the air’s temperature changes, so does the amount of water the air can hold. (Air can hold more water vapor as the temperature heats up.) Relative humidity compares the actual humidity to the maximum amount of water vapor the air can hold at any given temperature.

Whose idea was the heat index?

While the notion of humidity making days feel warmer is painfully apparent to anyone who has ever been outside on a soupy day, our current system owes a big debt to Robert G. Steadman, an academic textile researcher. In a 1979 research paper called, “An Assessment of Sultriness, Parts I and II,” Steadman laid out the basic factors that would affect how hot a person felt under a given set of conditions, and meteorologists soon used his work to derive a simplified formula for calculating heat index.

The formula is long and cumbersome, but luckily it can be transformed into easy-to-read charts. Today your local meteorologist just needs to know the air temperature and the relative humidity, and the chart will tell him or her the rest.

Is the heat index calculation the same for everyone?

Not quite, but it’s close. Steadman’s original research was founded on the idea of a “typical” person who was outdoors under a very precise set of conditions. Specifically, Steadman’s everyman was 5’7” tall, weighed 147 pounds, wore long pants and a short-sleeved shirt, and was walking at just over three miles per hour into a slight breeze in the shade. Any deviations from these conditions will affect how the heat/humidity combo feels to a certain person.

What difference does being in the shade make?

Quite a big one. All of the National Weather Service’s charts for calculating the heat index make the reasonable assumption that folks will look for shade when it’s oppressively hot and muggy out. Direct sunlight can add up to 15 degrees to the calculated heat index.

How does wind affect how dangerous the heat is?

Normally, when we think of wind on a hot day, we think of a nice, cooling breeze. That’s the normal state of affairs, but when the weather is really, really hot—think high-90s hot—a dry wind actually heats us up. When it’s that hot out, wind actually draws sweat away from our bodies before it can evaporate to help cool us down. Thanks to this effect, what might have been a cool breeze acts more like a convection oven.

When should I start worrying about high heat index readings?

The National Weather Service has a handy four-tiered system to tell you how dire the heat situation is. At the most severe level, when the heat index is over 130, that's classified as "Extreme Danger" and the risk of heat stroke is highly likely with continued exposure. Things get less scary as you move down the ladder, but even on "Danger" days, when the heat index ranges from 105 to 130, you probably don’t want to be outside. According to the service, that’s when prolonged exposure and/or physical activity make sunstroke, heat cramps, and heat exhaustion likely, while heat stroke is possible.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This article has been updated for 2019.

Is the Heat Index Real?

MarianVejcik/iStock via Getty Images
MarianVejcik/iStock via Getty Images

Complaining about the humidity is a mainstay of small talk. “It’s not the heat that gets you, it’s the humidity” is a common refrain around the South, just as “it’s a dry heat” is a go-to line in the desert Southwest. The clichés aren’t wrong on this one—a hot and humid day can have a dramatic effect on both your comfort and your health. We can measure this very real impact on your body using the heat index. 

The heat index is the temperature it feels like to your body when you factor in both the actual air temperature and the amount of moisture in the air. If the heat index is 103°F, that means that the combination of heat and humidity has a similar physical impact on your body as it would if the actual air temperature were 103°F. Even though it’s tempting to think of the heat index as an exaggerated temperature that only exists to make the heat sound worse than it really is, scientists came up with the measurements after decades of medical and meteorological research devoted to studying the impact of heat and humidity on the human body. It’s the real deal.

The dew point is an important component of the heat index. The dew point is the temperature at which the air would reach 100 percent relative humidity, or become fully saturated with moisture like on a foggy morning. Since cooler air can’t hold as much moisture as warmer air, lower dew points reflect lower moisture levels and higher dew points indicate higher moisture levels. Dew points below 60°F are comfortable, while readings reaching 70°F and even 80°F range from muggy to downright oppressive.

Measuring humidity on a hot day is important because moisture is how your body naturally cools itself off. Your sweat cools the surface of your skin through a process known as evaporative cooling. If the air is packed with moisture, it takes longer for your sweat to evaporate than it would in more normal conditions, preventing you from cooling off efficiently. The inability to lower your body temperature when it’s hot can quickly lead to medical emergencies like heat exhaustion or heat stroke, which is why the heat index is such an important measurement to pay attention to during the summer months.

The heat index is generally considered “dangerous” once the value climbs above 105°F, and your risk of falling ill increases the higher the heat index climbs.

Dry climates can have the opposite effect on your body, with the distinct lack of moisture in the air making it feel cooler to your body than it really is. Summers get oppressively hot in places like Arizona and Iraq, but the heat doesn’t affect residents as severely because the air is extremely dry. Dew points in desert regions can hover at or below 32°F even when the air temperature is well above 100°F, which is about as dry as it can get in the natural world.  

In 2016, a city in Kuwait measured the all-time highest confirmed temperature ever recorded in the eastern hemisphere, where temperatures climbed to a sweltering 129°F during the day on July 21, 2016. The dew point there at the same time was nearly 100 degrees cooler, leading to a heat index of just 110°F, much lower than the actual air temperature. That’s not necessarily a good thing. Extreme heat combined with extreme aridity can make your sweat evaporate too efficiently, quickly dehydrating you and potentially leading to medical emergencies similar to those you would experience in a much more humid region of the world. 

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

This story has been updated for 2019.

SECTIONS

arrow
LIVE SMARTER