Man's best friend may understand you as well as your actual best friend might.
Research comparing the brain function of dogs and humans found that dogs have "voice areas" in their brains located in the same region as humans. And in both species, this part of the brain is adept at understanding the subtleties between our voice tones that express our different emotions.
"Dogs and humans share a similar social environment," Attila Andics of MTA-ELTE Comparative Ethology Research Group in Hungary said in a press release. "Our findings suggest that they also use similar brain mechanisms to process social information. This may support the successfulness of vocal communication between the two species."
Researchers scanned the brains of 11 dogs with an fMRI scanner -- a device that measures brain activity -- while they listened to almost 200 dog and human sounds. The samples included whining, crying, happy barks and laughing.
Both dog and human brains lit up in the voice area -- which was located in similar, corresponding locations -- when they heard the sounds.
They also saw that both dogs and humans processed emotion-ridden sounds the same way. For example, the primary auditory cortex was activated more when a happy sample was played more than a sad sound in both species.
"This method offers a totally new way of investigating neural processing in dogs," Andics says. "At last we begin to understand how our best friend is looking at us and navigating in our social environment."
Before you join a pack, there were some key differences: 39 percent of the dog's vocal regions were activated most by sounds made by dogs, and 48 percent lit up due to non-verbal noises. Only 13 percent responded the most to human vocalizations.
As for humans, 10 percent of their vocal region were most activated due to environmental sounds, and just 3 percent responded the most to non-vocal noises.
The study was published Feb. 20 in Current Biology.
The study suggests that the voice area must have evolved at least 100 million years ago, which is the age of the last known common ancestor between our two species.
Marc Bekoff, a fellow of the Animal Behavior Society and a former professor of ecology and evolutionary biology at the University of Colorado, Boulder, told Wired that being able to understand sounds and emotions is key for dogs.
The fact that dogs were bred by humans may have helped make them more akin to our emotions, but chances are their capacity to understand emotion was already pretty advanced before we made them pets. Wolves, coyotes and other undomesticated canines have been observed to be vocal and responsive to emotion.
"It's not a surprising finding, but it's an important finding," said Bekoff, who was not involved in the study.