Tag Archives: Current Biology

A bond that goes way back

The special relationship between humans and dogs may go back 27,000 to 40,000 years, according to genomic analysis of an ancient Taimyr wolf bone reported in the Cell Press journal Current Biology on May 21. Earlier genome-based estimates have suggested that the ancestors of modern-day dogs diverged from wolves no more than 16,000 years ago, after the last Ice Age.

The genome from this ancient specimen, which has been radiocarbon dated to 35,000 years ago, reveals that the Taimyr wolf represents the most recent common ancestor of modern wolves and dogs.

his image compares an ancient Taimyr Wolf bone from the lower jaw to a modern pipette.  Photo by Love Dalén

This image compares an ancient Taimyr Wolf bone from the lower jaw to a modern pipette. Photo by Love Dalén

“Dogs may have been domesticated much earlier than is generally believed,” says Love Dalén of the Swedish Museum of Natural History. “The only other explanation is that there was a major divergence between two wolf populations at that time, and one of these populations subsequently gave rise to all modern wolves.” Dalén considers this second explanation less likely, since it would require that the second wolf population subsequently became extinct in the wild.

“It is [still] possible that a population of wolves remained relatively untamed but tracked human groups to a large degree, for a long time,” adds first author of the study Pontus Skoglund of Harvard Medical School and the Broad Institute.

The researchers made these discoveries based on a small piece of bone picked up during an expedition to the Taimyr Peninsula in Siberia. Initially, they didn’t realize the bone fragment came from a wolf at all; this was only determined using a genetic test back in the laboratory. But wolves are common on the Taimyr Peninsula, and the bone could have easily belonged to a modern-day wolf. On a hunch, the researchers decided to radiocarbon date the bone anyway. It was only then that they realized what they had: a 35,000-year-old bone from an ancient Taimyr wolf.

The DNA evidence also shows that modern-day Siberian Huskies and Greenland sled dogs share an unusually large number of genes with the ancient Taimyr wolf.

“The power of DNA can provide direct evidence that a Siberian Husky you see walking down the street shares ancestry with a wolf that roamed Northern Siberia 35,000 years ago,” Skoglund says. To put that in perspective, “this wolf lived just a few thousand years after Neandertals disappeared from Europe and modern humans started populating Europe and Asia.”

Source:  EurekAlert! media statement

Happy faces/sad faces

This is the experimental set-up used to test whether dogs can discriminate emotional expressions of human faces.  Photo by Anjuli Barber, Messerli Research Institute

This is the experimental set-up used to test whether dogs can discriminate emotional expressions of human faces. Photo by Anjuli Barber, Messerli Research Institute

Dogs can tell the difference between happy and angry human faces, according to a research published recently in the journal Cell Biology.

The discovery represents the first solid evidence that an animal other than humans can discriminate between emotional expressions in another species, the researchers say.

Previous attempts had been made to test whether dogs could discriminate between human emotional expressions, but none of them had been completely convincing. In the new study, the researchers trained dogs to discriminate between images of the same person making either a happy or an angry face. In every case, the dogs were shown only the upper or the lower half of the face. After training on 15 picture pairs, the dogs’ discriminatory abilities were tested in four types of trials, including (1) the same half of the faces as in the training but of novel faces, (2) the other half of the faces used in training, (3) the other half of novel faces, and (4) the left half of the faces used in training.

The dogs were able to select the angry or happy face more often than would be expected by random chance in every case, the study found. The findings show that not only could the dogs learn to identify facial expressions, but they were also able to transfer what they learned in training to new cues.

“Our study demonstrates that dogs can distinguish angry and happy expressions in humans, they can tell that these two expressions have different meanings, and they can do this not only for people they know well, but even for faces they have never seen before,” says Ludwig Huber, senior author and head of the group at the University of Veterinary Medicine Vienna’s Messerli Research Institute.

This research adds to the body of knowledge about the human-animal bond.  The researchers believe it is likely that the dogs associate a smile with a positive meaning and an angry expression with a negative one.

Source:  EurekAlert! media release

 

Dogs’ brains respond to human voices

Yet more research on how dogs’ brains work.  This time from a research team at Eötvös Loránd University in Hungary and published in the journal Current Biology.

Using functional MRI, the team could see where blood flowed in the brains of a group of 11 dogs.  The dogs had been specially trained using positive reinforcement techniques to lie still in the MRI scanner for six minutes.

A dog lies still in the fMRI scanner, wearing earphones to pipe in sounds as part of the study. (Photo by Eniko Kubinyi)

A dog lies still in the fMRI scanner, wearing earphones to pipe in sounds as part of the study. (Photo by Eniko Kubinyi)

which tracks blood flow to various areas of the brain, a sign of increased activity—to peer inside the minds of dogs. One of a handful of labs groups worldwide that’s using the technology in this way, they’ve used positive reinforcement training to get a study group of 11 dogs to voluntarily enter the fMRI scanner and stay perfectly still for minutes at a tRead more: http://www.smithsonianmag.com/science-nature/your-dog-can-tell-from-your-voice-if-youre-happy-or-sad-180949807/#DXcpTX0jfeQGFWVY.99
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The team played each dog a series of over 200 sounds across several MRI sessions.  The sounds included human voices, dog vocalizations, and meaningless noises.

When the results were compared, it showed that the dogs’ brains appear to have a dedicated area that displays more activity in response to voices (whether human speech or dogs barking) than other meaningless noises (such as glass breaking).

More importantly, that part of the brain shows more activity upon hearing an emotionally positive sound, as compared to a negative one.  This means that our dogs are able to distinguish a tone of voice that is positive from one that is negative. (Something many of us probably already knew)

The voice areas of the dogs’ brains is similar to that found in humans, suggesting that our species evolved from a common ancestor almost 100 million years ago, enabling a high degree of communication and social structure.

“We know that dogs don’t have language, per se, but we see now that dogs have very similar mechanisms to process social information as humans,” Attila Andics, lead researcher on the study says. “It makes us wonder what aspects of so-called ‘language skills’ are not so human-specific after all, but are also there in other species. That’s something we plan to look at.”

Source:  Smithsonian Magazine

Here are my earlier blogs about functional MRI studies on dogs:

they show that the dogs’ brains appear to have a dedicated area that displays more activity in response to voices (whether human speech or dogs barking) than other meaningless noises (such as glass breaking), and that part of this area shows more activity upon hearing an emotionally positive sound, as compared to a negative one.Read more: http://www.smithsonianmag.com/science-nature/your-dog-can-tell-from-your-voice-if-youre-happy-or-sad-180949807/#DXcpTX0jfeQGFWVY.99
Give the gift of Smithsonian magazine for only $12! http://bit.ly/1cGUiGv
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My dog wags on the right side (that’s the good side)

Whether your dog wags on the right side or the left means something – to other dogs and to observant humans…

Credit:  Siniscalchi et al.

Photo Credit: Siniscalchi et al.

Research by an Italian team has shown that dogs, like humans, have asymmetrically organized brains, with the left and right sides playing different roles.  The team has published their research in the journal Current Biology.

The research team had already found that dogs wag to the right when they feel positive emotions (upon seeing their owners, for instance) and to the left when they feel negative emotions (upon seeing an unfriendly dog, for example). That biased tail-wagging behavior reflects what is happening in the dogs’ brains. Left-brain activation produces a wag to the right, and right-brain activation produces a wag to the left.

The latest research, however, shows that the direction of tail-wagging means something to other dogs.  While monitoring their reactions, the researchers showed dogs videos of other dogs with either left- or right-asymmetric tail wagging. When dogs saw another dog wagging to the left, their heart rates picked up and they began to look anxious. When dogs saw another dog wagging to the right, they stayed perfectly relaxed.

Researcher Giorgio Vallortigara of the Center for Mind/Brain Sciences of the University of Trento says that the direction of tail-wagging a clear indication of right or left brain activation and could have many applications, such as determining state of mind during a visit to the vet.

So now that you know about this research, think about the wags on these dogs and what are they trying to say?