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12 Scientifically Cute Facts About Puppies

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Puppies are hard-wired to appeal to us, with their adorable squishy faces, little paws, and wet noses. But there is more to young dogs than downy fur and floppy ears. Here are 12 scientific facts about them to coo over:

1. THEY LIKE BABY TALK.

A January 2017 study found that puppies respond when humans speak in sing-song tones, but adult dogs couldn’t care less. Researchers from the University of Lyon at Saint-Etienne found that people speak more slowly and at a much higher pitch when talking to puppies (or pictures of them, at least) than when talking to humans or adult dogs. When the researchers played recordings of participants’ puppy talk to dogs, they found that the puppies showed greater responses to the cooing than to recordings of humans using their regular (human-directed) voices. Adult dogs, on the other hand, did not. It’s hard to say why that is, but it could be that puppies are wired to respond to high-pitched sounds, but they eventually grow out of it.

2. THEY CAN HELP YOU FOCUS.

Looking at cute pictures of puppies at work is more productive than you’d think. In a 2012 study, Japanese researchers found that viewing pictures of puppies made people better at tasks that required close attention. Viewing pictures of older dogs, however, was not as effective. People were more effective and more careful in accomplishing the tasks before them if they were flooded by the positive emotions of seeing an amazingly adorable baby animal. The researchers suggest that maybe people should look at cute things before driving or at work to help them focus.

3. THEY REALLY DO LIKE YOU.

In a Hungarian study published in 2005, researchers found that pet puppies show specific attachments to the humans that care for them. While even wolves that had been hand-raised from birth by humans didn’t show any preference for the people that raised them—they reacted the same way to strangers as to the caregivers they had spent their entire lives with—domestic puppies as young as 4 months old showed a significant preference to their owners. They followed and greeted their owners more than they did strange humans, and when their owner left, they tended to stand by the door waiting for them to return. This difference was observed in both puppies that had been hand-raised with extensive socialization and puppies that had been reared in a litter by their mothers, indicating that as a species, dogs have evolved to bond with their human owners.

4. THEIR SENSES DON'T DEVELOP UNTIL A FEW WEEKS AFTER BIRTH.

When they’re first born, puppies only respond to warmth, touch, and smell. Their eyes remain closed, and they can’t hear. Puppies don’t fully develop the ability to hear until they are 4 weeks old, and it is not until 6 weeks of age, on average, that they develop full vision. Once their senses develop, they begin exploring the world in earnest, beginning a critical period of socialization.

5. IT'S IMPORTANT TO FAMILIARIZE THEM WITH PEOPLE EARLY.

Studies [PDF] have shown that puppies are most socially malleable during their second month of life. During that time, their sensory systems are developed enough to let them explore, but they’re not yet fearful of new experiences. As one 1961 study on puppy litters isolated from humans found, puppies that aren’t played with showed "increasing tendency to withdraw from human beings after 5 weeks of age and unless socialization occurred before 14 weeks of age, withdrawal reactions from humans became so intense that normal relationships could not thereafter be established."

6. THEIR PHYSICAL AND EMOTIONAL DEVELOPMENT VARIES BY BREED.

Puppies don’t all develop on the same timeline. A 2015 study of almost 100 purebred dogs found that different breeds of dogs develop a sense of fear at different times in puppyhood. The researchers put puppies from 4 weeks old to 10 weeks old through several tests designed to provoke a fear response, like making them listen to a loud bang or explore a seesaw. They found that Cavalier King Charles spaniels didn’t show fear-related behavior (like crouching down) until later than German shepherds or Yorkshire terriers. While German shepherds typically began showing a fear response around 35 days old, the spaniels didn’t start avoiding scary stimuli until 55 days old.

7. THEY LEARN TO UNDERSTAND HUMAN GESTURES AS THEY AGE.

Dogs can understand human social cues like pointing, but it’s something that they learn over time. In 2007, researchers tested 6-, 8-, 16-, and 24-week-old puppies [PDF] on their ability to decode a human’s finger point. Though these researchers reported that dogs of all ages could understand the cue and use it to find food under a cup, subsequent analysis by another research group showed that actually, those skills improved over time [PDF]. The older the dogs were, the better they were able to understand the pointing and suss out the correct cup. In itself, the act of testing seemed to help them learn, too. The youngest puppies showed improvement between the first half of their trials and the second half, the 2008 follow-up analysis found.

8. THEY DON'T CRY AS MUCH AS ADULT DOGS.

Dogs aren’t born with very moist eyes. One 2012 study found that 4-week-old puppies do produce basal tears, but in much smaller quantities than adult dogs. Their eyes get wetter every day, finally reaching adult levels of tears at about 10 weeks old. By contrast, full-term human babies have eyes which are just as wet as those of adults, unless they’re born premature, in which case they have lower secretions of tears until a few weeks later. (These are just the tears that keep eyes moist, not the psychological kind.)

9. THEIR LITTER SIZE DEPENDS A LOT ON BREED.

How many puppies a dog has varies by breed. While a 2011 review of birth data from 224 dog breeds found that the average purebred dog litter consisted of five or so puppies (5.4, to be exact), older and smaller dogs tend to have fewer puppies. Rhodesian Ridgebacks gave birth to the most puppies (an average of 8.9 puppies per litter), while toy Poodles and Pomeranians gave birth to an average of 2.4 puppies at a time.

10. THEY'RE NOT ALWAYS PLANNED.

In one of the first benchmark studies on pet population trends in the U.S., researchers found that 43 percent of puppy litters in 1996 were unplanned—about 2.6 million compared to 3.38 million planned litters. That’s a lot less than the whopping 83 percent of kitten litters that were unplanned.

11. THEY CAN BE IDENTICAL TWINS.

In 2016, a veterinarian encountered what is thought to be the first verified instance of identical twin puppies. When South African vet Kurt de Cramer performed a C-section on a pregnant Irish wolfhound, he discovered that two male puppies shared the same placenta. Later, he had their DNA tested and confirmed that they were, in fact, identical twins.

12. THEIR BEHAVIORAL TRAITS AREN'T SET YET AT 8 WEEKS OLD.

A long-term study of 1235 German shepherd puppies bred at the Swedish Dog Training Center in the late 1970s and early 1980s found that at 8 weeks old, a dog’s personality is not yet developed enough to analyze. The researchers wanted to know if suitability tests for guide dogs and other working dogs could be accurately performed on puppies as young as 8 weeks old. They found that at that point, puppy behavior is still changing rapidly, and test results from that young wouldn’t reveal much about the future behavior of the dog as an adult. In other words, it’s O.K. if your puppy is an idiot (or rambunctious, or whiny)—he’ll grow out of it, hopefully.

All images via iStock.

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There May Be an Ancient Reason Why Your Dog Eats Poop
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Dogs aren't known for their picky taste in food, but some pups go beyond the normal trash hunting and start rooting around in poop, whether it be their own or a friend's. Just why dogs exhibit this behavior is a scientific mystery. Only some dogs do it, and researchers aren't quite sure where the impulse comes from. But if your dog is a poop eater, it's nearly impossible to steer them away from their favorite feces.

A new study in the journal Veterinary Medicine and Science, spotted by The Washington Post, presents a new theory for what scientists call "canine conspecific coprophagy," or dogs eating dog poop.

In online surveys about domestic dogs' poop-eating habits completed by thousands of pet owners, the researchers found no link between eating poop and a dog's sex, house training, compulsive behavior, or the style of mothering they received as puppies. However, they did find one common link between the poop eaters. Most tended to eat only poop that was less than two days old. According to their data, 85 percent of poop-eaters only go for the fresh stuff.

That timeline is important because it tracks with the lifespan of parasites. And this led the researchers to the following hypothesis: that eating poop is a holdover behavior from domestic dogs' ancestors, who may have had a decent reason to tuck into their friends' poop.

Since their poop has a high chance of containing intestinal parasites, wolves poop far from their dens. But if a sick wolf doesn't quite make it out of the den in time, they might do their business too close to home. A healthier wolf might eat this poop, but the parasite eggs wouldn't have hatched within the first day or two of the feces being dropped. Thus, the healthy wolf would carry the risk of infection away from the den, depositing the eggs they had consumed away in their own, subsequent bowel movements at an appropriate distance before the eggs had the chance to hatch into larvae and transmit the parasite to the pack.

Domestic dogs may just be enacting this behavior instinctively—only for them, there isn't as much danger of them picking up a parasite at home. However, the theory isn't foolproof. The surveys also found that so-called "greedy eaters" were more likely to eat feces than dogs who aren't quite so intense about food. So yes, it could still be about a poop-loving palate.

But really, it's much more pleasant to think about the behavior as a parasite-protection measure than our best pals foraging for a delicious fecal snack. 

[h/t The Washington Post]

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What Makes a Cat's Tail Puff Up When It's Scared?
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Cats wear their emotions on their tails, not their sleeves. They tap their fluffy rear appendages during relaxing naps, thrash them while tense, and hold them stiff and aloft when they’re feeling aggressive, among other behaviors. And in some scary situations (like, say, being surprised by a cucumber), a cat’s tail will actually expand, puffing up to nearly twice its volume as its owner hisses, arches its back, and flattens its ears. What does a super-sized tail signify, and how does it occur naturally without help from hairspray?

Cats with puffed tails are “basically trying to make themselves look as big as possible, and that’s because they detect a threat in the environment," Dr. Mikel Delgado, a certified cat behavior consultant who studied animal behavior and human-pet relationships as a PhD student at the University of California, Berkeley, tells Mental Floss. The “threat” in question can be as major as an approaching dog or as minor as an unexpected noise. Even if a cat isn't technically in any real danger, it's still biologically wired to spring to the offensive at a moment’s notice, as it's "not quite at the top of the food chain,” Delgado says. And a big tail is reflexive feline body language for “I’m big and scary, and you wouldn't want to mess with me,” she adds.

A cat’s tail puffs when muscles in its skin (where the hair base is) contract in response to hormone signals from the stress/fight or flight system, or sympathetic nervous system. Occasionally, the hairs on a cat’s back will also puff up along with the tail. That said, not all cats swell up when a startling situation strikes. “I’ve seen some cats that seem unflappable, and they never get poofed up,” Delgado says. “My cats get puffed up pretty easily.”

In addition to cats, other animals also experience piloerection, as this phenomenon is technically called. For example, “some birds puff up when they're encountering an enemy or a threat,” Delgado says. “I think it is a universal response among animals to try to get themselves out of a [potentially dangerous] situation. Really, the idea is that you don't have to fight because if you fight, you might lose an ear or you might get an injury that could be fatal. For most animals, they’re trying to figure out how to scare another animal off without actually going fisticuffs.” In other words, hiss softly, but carry a big tail.

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