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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.

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13 Facts About Opossums
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Opossums, which include the roughly 100 species in the order Didelphimorphia, are some of the most misunderstood animals in the Americas. They’re often thought of as dimwitted, dirty creatures whose most impressive trick is acting like roadkill. The truth is just the opposite: Opossums are smarter, cleaner, and more beneficial to humans than many of their woodland neighbors. Read on for more opossum facts.

1. OPOSSUMS AND POSSUMS AREN’T THE SAME ANIMAL.

In North America, opossum and possum describe the same thing, but in Australia the word possum refers to a completely different animal. Among the most well known of their respective types are the Virginia opossum and the brushtail possum. Both are small to medium sized, omnivorous marsupials, but the similarities end there. The possum looks like a cute cross between a squirrel and a chinchilla and it belongs to a different order than the North American mammal that shares (most of) its name. Despite the potential for confusion, possum is accepted as the shortened version of opossum in this part of the world (and if you see the word possum in this list, you can assume it’s referring to the animal from the Americas).

2. THEY’RE THE ONLY MARSUPIALS FOUND NORTH OF MEXICO.

Marsupials—mammals that carry and nurse their young in pouches—are absent from much of the world, and in Canada and the United States opossums are the sole representatives of the group. Like other marsupials, mother possums give birth to tiny, underdeveloped offspring (called joeys) that immediately crawl into a pouch where they live and nurse during their first months of life. Only once they’ve grown big and strong enough do they venture out, transitioning between their mother’s back and the warmth of the pouch until they mature into adults.

3. THEY CAN’T CHOOSE WHEN THEY PLAY DEAD.

Possum playing dead.
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Perhaps the most famous characteristic of the opossum is its tendency to play dead in front of predators. When the animal experiences intense fear in the face of danger, it seizes up and flops to the ground where it can remain for hours staring blankly ahead and sticking out its tongue. It’s an impressive defensive mechanism, but its effectiveness can’t be chalked up to the possum’s acting skills. Possums have no control over when they play dead or for how long they do it: The comatose-like state is an involuntary reaction triggered by stress.

4. AN OFFENSIVE ODOR SELLS THE PERFORMANCE.

A picture of a possum playing dead doesn’t really do it justice. To get the full experience, you need to be standing over to it to smell the putrid odor it emits when pretending to be a corpse. The smelly substance it secretes from its anus is just one more reason for foxes and bobcats to look for their dinner elsewhere.

5. THEY SLOW THE SPREAD OF LYME DISEASE.

Even if possums aren’t the cutest creatures in the forest, they should be a welcome addition to your backyard. Unlike other mammals that carry ticks, and therefore spread Lyme Disease, possums gobble up 90 percent of the ticks that attach to them. According to the National Wildlife Federation, a single possum consumes 5000 of the parasites per tick season. That means the more possums that are in your area, the fewer ticks you’ll encounter.

6. THEIR MEMORIES ARE SURPRISINGLY SHARP.

Possum looking up at table.
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Opossums have impressive memories—at least when it comes to food. Researchers found that possums are better at remembering which runway led to a tasty treat than rats, cats, dogs, and pigs. They can also recall the smell of toxic substances up to a year after trying them.

7. THEY’RE IMMUNE TO MOST SNAKE VENOM.

While most animals look at a snake and see danger, a possum sees its next meal. The animals are immune to the venom of nearly every type of snake found in their native range, the one exception being the coral snake. Possums take advantage of this adaptation by chowing down on snakes on a regular basis.

Researchers have been trying to harvest possums’ antivenom powers for decades. A few years ago, a team of scientists made progress on this front when they recreated a peptide found in possums and and found that mice given the peptide and rattlesnake venom were successfully protected from the venom’s harmful effects.

8. THEY ALMOST NEVER GET RABIES.

While possums aren’t totally immune to rabies (a few cases have been documented), finding a specimen with the disease is extremely unlikely. Marsupials like possums have a lower body temperature than the placental mammals that dominate North America—in other words, their bodies don’t provide a suitable environment for the virus.

9. THEIR TAIL ACTS AS A FIFTH APPENDAGE.

Baby opossum hanging from a tree branch by its tail.
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Opossums are one of a handful of animals with prehensile tails. These appendages are sometimes used as an extra arm: They can carry grass and leaves for building nests or grip the sides of trees to provide extra stability while climbing. Baby possums can even use their tails to hang from branches upside down as they’re often depicted doing in cartoons. But it’s a myth that possums sleep this way: Their tails are only strong enough to hold them for a short amount of time.

10. THEY’RE CONSTANTLY SELF-GROOMING.

Thanks to their whole acting-and-smelling-like-a-corpse routine, opossums aren’t known as the most sanitary animals in nature. But they take cleanliness seriously: The Washington Department of Fish and Wildlife writes that possums, like housecats, use their tongue and paws to groom themselves frequently and thoroughly. Possums largely lack sweat glands, and this behavior is believed to help them cool down. It also has the added effect of rendering them odorless (when they’re not secreting stinky predator-repellant, that is).

11. THEIR EYES AREN’T TOTALLY BLACK.

Close-up on opossum's face.
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One of the opossum’s most recognizable features is its pair of opaque eyes. Opossum eyes do have whites and irises, but because their pupils are so large, their eyes appear completely black from a distance. The exaggerated pupil dilation is thought to help the nocturnal animals see after the sun goes down.

12. THEY’RE SOCIAL CREATURES.

It was long assumed that opossums like to keep to themselves, but a study published in the journal Biology Letters suggests they have a social side. Researchers at the Federal University of Pernambuco in Recife, Brazil observed some possums in captivity sharing dens even if they weren’t mates. In one case, 13 white-eared opossums of various age groups were cohabiting the same space. The scientists suspect that male and female possums living in the wild may even build nests together as a way to trigger the female’s reproductive hormones.

13. THEIR REPRODUCTIVE SYSTEMS ARE COMPLICATED.

The way it gives birth and raises its young isn’t the only thing that’s interesting about the opossum's reproductive life. Females have two vaginal tracts and two uteri, and males in turn have a forked or bifurcated penis. This is fairly typical for marsupials, but when European colonizers first landed in North America centuries ago, they didn’t know what to make of the confusing genitalia. One explanation they came up with was that male opossums impregnated females through the nose.

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Hero Crayfish Cheats Death By Removing Its Own Claw to Escape Pot of Boiling Water
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There remains a perpetual debate over the ethical consequences of taking a crustacean and boiling it alive. In early 2018, Switzerland actually made it illegal to give living lobsters a scalding hot bath. (Instead, chefs are expected to stun them electronically before submersion.) Scientists can’t reach a conclusion over whether decapods feel pain—or if we can even define what that means for them.

While humans argue, some clawed sacrifices are taking action. A crayfish filmed by a Facebook user in China is making the internet rounds and being hailed as a hero after taking dramatic measures to escape a boiling pot of water.

In the footage, the crayfish appears to be unable to extricate its left appendage from a bubbling vat of doom. Rather than succumb, the crayfish uses its right claw to sever its compromised claw and scurry off. At 11 seconds, it’s the best summary of a Saw film possible.

“Juike,” the user who originally posted the video to the Weibo social media site, says he has taken the crafty invertebrate home and put him in an aquarium as a pet. The tiny survivalist may even regrow his lost limb, as crawfish are able to do, although it might not reach its former size.

Crayfish are in inherent danger of being turned into soup in China, where specialty restaurants devoted to their preparation are popping up. Some observers believe their popularity is due to diners having to step away from phones and social media in order to use both hands to peel away at their shells.

[h/t BBC]

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