The images revealed that dog brains have voice areas and that they process voices in the same way that human brains do, the team reports online today in Current Biology. And because these voice areas are found in similar locations in the brains of both dogs and humans, the scientists suggest that they likely evolved at least 100 million years ago, when humans and dogs last shared a common ancestor, an insectivore. Indeed, some think that brain areas for processing vocal sounds could be discovered in more species.
Still, when voice areas were first discovered in humans, they were thought to be special and somehow tied specifically to the evolution of language. "So what are they doing in dog brains?" Andics asks.
The answer lies, he thinks, in what the scans also revealed: Striking similarities in how dog and human brains process emotionally laden sounds. Happy sounds, such as an infant's giggle, made the primary auditory cortex of both species light up more than did unhappy sounds, such as a man's harsh cough. "It shows that dogs and humans have similar brain mechanisms for processing the social meaning of sound," Andics says, noting that other research has shown that dogs "respond to the way we say something rather than to what we say." The similarity in auditory processing, he adds, "helps explain why vocal communication between the two species is so successful."