You may not guess it when they are happily gnawing on your shoelaces, but goats are smart, complex creatures. Their emotional intelligence is a particularly interesting point of inquiry. Research has shown that goats, highly social animals that congregate in herds, are sensitive to human facial expressions, and that their vocalizations encode information about their emotional states. Now, a new study suggests that goats are able to distinguish between positive and negative emotions expressed in other goats’ calls—and that these calls might affect how the listener is feeling too.
Scientists are keen to learn more about how non-human animals communicate emotion—an important evolutionary trait, given that “expression of emotions can regulate social interactions and promote coordination within a group,” an international team of researchers explains in Frontiers in Zoology. Hoping to shed new light on one farm animal species, the researchers headed to the Buttercup Sanctuary for Goats in Kent, U.K., where they conducted an experiment with 24 adult goats. One at a time, the goats were brought into a rectangular pen, where a loudspeaker had been set up outside the main gate and hidden with camouflage netting, rendering the goats unable to see it.
Next, the researchers looked to vocalizations that had been recorded from other goats during a previous study. The recordings consisted of both “positive” and “negative” calls; the positive calls were collected from goats as they saw someone approaching with a bucket of food, and the negative ones had been collected from goats that had seen another animal being fed, while not getting any snacks themselves. Some of the negative calls had also been recorded among goats that were kept in isolation for five minutes. But lead study author Luigi Baciadonna tells Clare Wilson of New Scientist that “[t]his was not extreme distress–I don’t think most people could tell the difference in their calls.”
The researchers played the goats a sequence of recordings: nine positive followed by three negative, or vice versa, and then a final call that matched the emotion of the first phase. Scientists found that the goats looked towards the speaker when the first recordings were played, then seemed to lose interest as the calls continued. But when the emotional tone of the vocalizations shifted, the animals were likely to look back at the speaker—suggesting that they were picking up on the difference. It took the goats a moment to register the change; the animals were more likely to look up on the second vocalization of the set of three recordings. But the researchers nevertheless posit that the goats seemed able to “discriminate emotions conveyed in calls.”
It wasn’t just the goats’ behavioral clues that led the study authors to this conclusion. The team also fitted their animal subjects with external heart monitors, and found that the goats’ heart rate variability—or the variation in time between each heart beat—was greater when positive calls were played. This in turn suggests that goats “are able to perceive a positive or negative [emotion] and it could affect how they are feeling as well,” study author Alan McElligott tells Meghan Holohan of Today.
From an evolutionary perspective, this makes sense. “Perceiving the emotional state of another individual through its vocalisations and being affected by those vocalisations have a strong adaptive value considering the dynamics of social organisations where, for example, group size and composition changes over time,” the study authors write. Like many other social animals, goats live in environments where they might not be able to stay in constant visual contact with one another—so being able to interpret their buddies’ calls would be advantageous.
The study authors also hope that their insights into goats’ emotional perceptiveness might influence the way these animals are treated as livestock. “They are not meat and milk or hair producing machines,” McElligott tells Holohan. “They have complex social lives.”