Why cats purr and 9 other facts you didn't know about them

Domestic cats, invasive exotic species in this country 0:43

(CNN Spanish) --

When they are just a few days old, cats learn to purr, that characteristic sound that in general for us humans means that they are well.

However, behind the purr there is more than we imagine.

Veterinarians suggest that when cats start purring within days of birth, the sound is a way of telling their mothers they're there and okay, according to a review by the US Library of Congress.

It is also a mechanism to strengthen ties with mothers.

The purr, however, continues when they enter adulthood.

"Many suggest that a cat purrs for contentment and pleasure. But a cat also purrs when he is hurt and in pain," the post explains.

Purring, with a low-frequency vibration, is a "natural healing mechanism," suggests Dr. Elizabeth Von Muggenthaler.

An article in the journal

delves into this view: cats also purr when they are "under pressure", for example during a visit to the vet.

The difference between this sound and others made by cats is that they are produced during the entire respiratory cycle, that is, during inhalation and exhalation.

And the frequency is between 25 and 150 Hertz.

"Several researchers have shown that sound frequencies in this range can improve bone density and promote healing," the journal explains.

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In tribute to the felines in their day, we also leave you another nine facts about them that you may not know.

1. Do you think your cat sleeps too much?

The average sleep is 12 to 18 hours a day, with a very different pattern from that of humans.

More than half of cats sleep between 12 and 18 hours a day, according to the Sleep Foundation.

Unlike humans, they do not sleep most of those hours during a single period but have a sleep pattern called polyphasic.

This means that they sleep several times a day, in periods that last between 50 and 113 minutes.

Cats have a circadian rhythm, that is, a kind of internal biological clock that guides their sleep schedules.

However, unlike the diurnal cycle of humans who are naturally disposed to sleep at night and be awake during the day, cats have a twilight cycle with two cycles of activity: one before sunrise and one around sunset .

2. Sleeping with you is beneficial for your health

With all the time cats spend sleeping, this fact may be especially important to you: Sleeping in bed with the humans they live with helps them bond, and by doing so "they get additional health benefits, including increased beneficial neurotransmitters like oxytocin and dopamine, the feel-good hormones," Dr. Dana Varble, chief veterinary officer for the North American Veterinary Community, told CNN.

But watch out!

That they sleep with you, in some cases, can bring you harm.

In fact, experts have traditionally said that this habit interferes with quality sleep, although in specific situations it brings benefits.

So yes or no?

Everything you need to know is in this article.

3. Not so long ago, cats were considered old at 8 years old.

The figure changed drastically

Thanks to improved nutrition, indoor living and improved treatments for cats, a feline is now considered old when it's 12 to 14 years old, according to Cornell University School of Veterinary Medicine.

It is not unusual for veterinarians to see patients who are in their 20s.

Older cats, the university says, tend to be less active and playful and may have changes in weight and sleep more.

However, experts caution, you shouldn't automatically attribute these types of changes in behavior and body to aging because they can also be signs of disease.

4. Even if they don't show it to you, cats form bonds with people

The indifference of cats, especially when compared to dogs, can be painful.

However, both pets respond to the people they've bonded with in similar ways and can form secure or insecure bonds with them, according to a 2019 study.

"Like dogs, cats show social flexibility with respect to their attachments to humans," study author Kristyn Vitale said at the time.

"Most cats are securely attached to their owner and use them as a source of security in a novel environment."

Read all the details here. 

5. They understand their name... but they may choose to ignore you when you call them.

Cats can distinguish their names from other random sounds, according to a study done in Japan.

This means that your cat simply chooses not to respond to your calls... just because.

To do this study, the researchers chose nouns with roughly the same stress and length as the cat's name and had both the cat's owner and a stranger record them.

They played the audio to the cats with 15-second intervals between each sound.

Regardless of who was speaking, most of the cats reacted in some way, shaking their heads or pricking up their ears when their names were called.

6. Cats can track your "invisible presence" using only their ears.

Another study out of Japan found that a stationary cat can track its owner's location using audio cues, specifically your voice.

Other animals, such as vervet monkeys and meerkats, also demonstrate this sense.

According to the study, this ability to create mental images based on sound and other stimuli indicates complex thinking.

This ability is especially important for animals that have to hunt prey in poor visibility.

7. There is a popular island where the number of cats exceeds that of humans

On Japan's Cat Island (Tashirojima) dogs have long been excluded and cats outnumber humans.

Local fishermen take great care of them and have an altar for cats where they leave offerings to ensure a good catch.

The most prominent structure on the island, the Manga Building and Camp, is adorned with a pair of pointed ears, in tribute to the island's lucky charms.

It is not the only cat island in Japan.

Ainoshima, in a more remote location, also has a multitude of happy cats that often gather at the port to wait for fishing boats or ferries to dock.

8. There are those who consider cats "the ecological axis of evil"

If you're a feline lover, you won't like this stark reality: America's cats kill between 1.4 and 3.7 million birds each year and are responsible for dozens of mammal extinctions.

There is a conservation organization that describes them as "the ecological axis of evil".

"You leave them in any environment and they are capable of killing anything that is smaller than them and even things that are a little larger. They are like a meat-eating machine," journalist Abigail Tucker, author of the book, said about them. "The lion in the room: How cats tamed us and took over the world."

9. There are 5 types of cat owners.

Which one are you?

This research is not so much about cats, but about cat owners, but it has an impact on the lives of felines.

While some owners embrace their cats' wilder tendencies and allow them the space to roam outside, others prefer to breed house cats, keeping their furry friends indoors and under supervision, according to the University of Exeter study. In England.

The five defined categories of owners are:

Which one are you?

With reporting from CNN's Skylar Mitchell, Alice Robb, Sandee LaMotte, Ashley Strickland and Allen Kim.

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