A voice gives you a lot of information in just a few seconds. How do our brains make sense of this rich vocal stream, and so quickly? In 2000, scientists scanned people’s brains and discovered a piece of neural real estate that’s dedicated to the task: a spot above the ear that responds to vocal sounds more strongly than other types of sounds.
This result was intriguing partly because the neuroscience world was buzzing about the specificity of other brain areas, notes Pascal Belin, a neuroscientist at the University of Glasgow and the lead author of the 2000 voice study. Just a few years earlier, another group had shown that a region in the visual cortex, the fusiform face area, is tuned to faces. These studies posed obvious evolutionary questions, Belin says. “These voice regions respond to speech and non-speech. So, are they uniquely human, or not?”
That was answered in 2008, when another lab reported that macaque monkeys have a similar voice-sensitive region in their brains. The area responded more to the voices of other macaques than to vocalizations of other species or non-voice sounds. “With that paper, it became clear: these regions didn’t just appear with humans,” Belin says. “It’s evolutionarily much older.”
You can imagine how interpreting the voices of other members of your species would be evolutionarily advantageous, whether for discerning a rival’s fury or a lover’s desire. That monkey paper suggested that voice-sensitive brain regions existed in the last common ancestor of humans and macaques, which roamed the earth some 30 million years ago.
A brain-scanning study published today in Current Biology reports similar voice regions in the dog brain. One region responds selectively to dog vocalizations, while a nearby area responds to the emotional cues of a voice, regardless of whether the voice came from a dog or from a human. Researchers don’t agree on the evolutionary implications of these results (more on that later). Still, the study may shed light on why dogs and people get on so well.
“Dogs use very similar brain mechanisms to process social and emotional information as humans do,” says Attila Andics, a researcher in the MTA-ELTE Comparative Ethology Research Group in Budapest, who led the new study. “This probably helps the dogs tune in to the feelings of their owners, and also probably helps humans tune in to the feelings of their dog.”