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What Do Dogs Tell Each Other by Wagging?

What do different wags mean? Canines know, and thanks to a new study, humans do too. Continue reading →

Dogs communicate with each other using their tails, and new research is helping to decipher what each tail wag means.

The direction of the tail wag - left or right - turns out to be very important, according to a study in the latest Current Biology.

While all wags look about the same to a glancing human, dogs are really clued into their direction and the hidden meaning behind that.

PHOTOS: The Earliest Dogs

When canines are distressed, such as when they see an unfriendly dog, they tend to wag their tails to the left.

This all occurs because the tail wagging is reflecting what's happening in the dogs' brains, according to lead author Giorgio Vallortigara, a researcher at the University of Trento's Center for Mind/Brain Sciences, and his colleagues.

They found that left-brain activation produces a wag to the right, and right-brain activation produces a wag to the left.

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"The direction of tail wagging does in fact matter, and it matters in a way that matches hemispheric activation," Vallortigara said in a press release.

"In other words, a dog looking to a dog wagging with a bias to the right side - and thus showing left-hemisphere activation as if it was experiencing some sort of positive/approach response - would also produce relaxed responses," continued Vallortigara.

"In contrast, a dog looking to a dog wagging with a bias to the left - and thus showing right-hemisphere activation as if it was experiencing some sort of negative/withdrawal response – would also produce anxious and targeting responses as well as increased cardiac frequency. That is amazing, I think."

As Vallortigara indicated, the study found that dogs that see another dog wagging to the left experience anxiety and increased heart rates. Dogs that see another dog wagging to the right stay perfectly relaxed.

The researchers don't think that dogs are intentionally communicating with their tails, in the way that some humans communicate visually with sign language. Instead, they believe it's more of a byproduct tied to the inner workings of doggy brains.

Nevertheless, the info is useful to dogs - and to humans - with the researchers calling on veterinarians to take note.

"It could be that left/right directions of approach could be effectively used by vets during visits of the animals," Vallortigara said, "or that dummies could be used to exploit asymmetries of emotional responses."

So don't be surprised if, one day, you spot a realistic toy dog propped up at your veterinarian's office, happily wagging its tail to the right.

Image: Siniscalchi et al.

A pointer named “Major” is identified as the first known example of a modern dog. A description of the dog was found in a now-obscure 1865 edition of a Victorian journal called The Field. It marks the earliest reported dog breed based on physical form and pedigree. “The invention of ‘breed,’ physically and imaginatively, still shapes how we see and think about dogs today,” Michael Worboys, Director of the University of Manchester’s Centre for the History of Science, Technology and Medicine, told Discovery News. Worboys and his team found the information concerning “Major” while preparing a new museum exhibit on dogs.

The first domestication of dogs was thought to have taken place 31,680 years ago -- but new research suggests the skull in question likely belong to a wolf. This particular specimen was found with a still-visible mammoth bone in its mouth.

The paleolithic dog remains resembled a modern Siberian husky, but suggest an animals that was significantly larger. Today, the Siberian husky, Samoyed and Alaskan malamute breeds are all closely related. "The most remarkable difference between these dogs and recent dog breeds is the size of the teeth,” paleontologist Mietje Germonpré said. Other early dog breeds, with a focus on the U.K., are featured in the museum exhibit curated by Worboys and his team. Entitled “Breed: The British and Their Dogs,” the exhibit runs at the University of Manchester museum through April 14.

Another team of researchers, led by Heidi Parker of the National Human Genome Research Institute, used DNA analysis to determine the genetic relationships of numerous dog breeds. One such ancient breed is the Afghan hound. As its name suggests, it's native to the Middle East. It’s one of the oldest dog breeds in existence, and was originally used for hunting hares and gazelles.

Parker and her team found that Akitas are yet another ancient breed. These dogs originated in Asia and are genetically similar to chow chows. The breed was not included in the first dog show. “The first dog show was in 1859 when only two varieties were shown: pointers and setters,” Worboys said. It had nothing to do with the handsome Akita’s looks, as he explained that the first dog show was “for gun dogs only.”

The sleek-bodied saluki comes from Iran, where its distant ancestors might have once lived near the earliest farmers from the Fertile Crescent. Dogs in this region evolved the ability to eat a starch-rich diet around 12,000 years ago. “Our findings show that it was crucial to early dogs to be able to thrive on a diet rich in starch,” Uppsala University’s Erik Axelsson, who led a related study, told Discovery News. “That indicates that dog domestication may be linked to the development of agriculture. It is possible that dogs may have been domesticated independently at locations where agriculture developed early, such as the Fertile Crescent and China.”

One of the most ancient dog breeds native to the United States is the Alaskan malamute. The DNA study found that they are genetically similar to Siberian huskies. This large, muscular dog was used -- and still is -- for pulling sleds, hauling freight by other means, and for additional work tasks.

The basenji is “an ancient African breed,” according to Parker and her colleagues. While “Major” the pointer is the first documented modern breed of dog, the basenji is arguably the first dog to be heavily bred by humans. Although this dog hails from central Africa, paleontologists believe its wolf ancestors originally came from eastern Asia.

In China, the chow chow is affectionately referred to as Songshi Quan, meaning “puffy-lion dog.” It is genetically close to the Akita, also from Asia. It represents yet another early breed.

Of the four most ancient known Asian dog breeds, the shar-pei was the first to diverge from a wolf ancestor, suggesting it is the oldest known Asian breed. This dog is famous for its deep wrinkles and blue-black tongue. Mutations of the same gene that causes wrinkles in these dogs can also cause wrinkling of human skin.