Wired for voices: Conserved brain responses in mammals
For social species, distinguishing vocalizations from other sounds (e.g., machine sounds or water dropping) and recognizing when a voice belongs to a member of the same species can be crucial for survival and reproduction. “Although vocal sounds carry important information for many animals, it was previously unclear how these abilities are reflected in the brain across evolutionarily distant mammal species,” says Boglárka Morvai, postdoctoral researcher at the Neuroethology of Communication Lab and first author of the study.
Human participants, family dogs, and family pigs all took part in the same auditory experiment, listening to a variety of sounds including human, dog, and pig vocalizations (e.g., human sighs or coughs, dog barking, pig grunts), as well as non-vocal environmental noises. EEG electrodes, placed gently on the head, recorded the brain’s rapid electrical responses. The animals, relaxed and at ease with their human companions, participated without training or sedation.
„The results revealed a two-step pattern in the brain’s response. In humans and pigs, vocalizations of any kind triggered distinct brain activity almost immediately, within 200 ms after stimulus presentation, suggesting that such sounds stand out as especially salient. Recognition of a voice belonging to one’s own species appeared later, only after 300 ms in all three species, reflecting a more complex process of categorizing the vocalization. Remarkably, these patterns were very similar despite the large evolutionary distance between the three species, pointing to shared neural mechanisms that likely predates the divergence of their lineages some 90 million years ago.”
“Surprisingly, even though the tested dogs and pigs live closely alongside people, their brains didn’t show a special sensitivity for human voices,” notes Lilla Magyari, an earlier member of the lab, now associate professor at University of Stavanger, Norway, who co-supervised the study. “This supports the idea that these abilities were not affected by recent domestication, but are part of an ancient mammalian heritage.”
The findings not only shed light on the deep evolutionary roots of voice perception, but also highlight the value of studying companion animals to better understand the human brain. As Attila Andics, the PI of the lab explains, “Our results show that by working with animals who trust us enough to take part in these experiments, we can uncover fundamental biological mechanisms that have shaped communication for millions of years.”