Goats can pick out emotional changes in the bleats of other goats, new research suggests.
Researchers from Queen Mary University of London say the discovery has important implications for how domestic animals, particularly livestock species, are cared for.
When the emotion of a goat call changes, the likelihood of the animals looking towards the sound also changes.
In an ideal world we should really be giving these animals the best conditions in which to live
Dr Alan McElligott who led the study at Queen Mary University of London, said the research suggests there is a potential for emotional contagion among the animals.
He added: “It means that if an individual suffering and if it is producing negative calls, it can potentially negatively affect all the individuals around it as well and push them into a more negative state.”
Dr McElligott, who is now based at the University of Roehampton, continued: “Often people switch off in terms of livestock welfare because it allows them to eat meat without really thinking of the consequences, and often people considered livestock relatively simple animals.
“But here we are showing that not only do goats produce different sounding calls depending on whether they are in a positive or negative state, but the other individuals around them can actually tell the difference and are potentially affected in a physiological way.”
“In an ideal world, we should really be giving these animals the best conditions in which to live so that they are not producing these negative calls too often.”
Published in the journal Frontiers in Zoology, the study also shows the goats’ heart-rate variability – the variation in time between each heartbeat – was greater when positive calls were played compared to when negative calls were played.
According to researchers, this is the first strong evidence goats are not only able to distinguish the emotion in calls, but also that their own emotions are potentially affected.
Luigi Baciadonna, lead author of the study, said: “Despite its evolutionary importance, social communication of emotions in non-human animals is still not well understood.
“Our results suggest that non-human animals are not only attentive, but might also be sensitive to the emotional states of other individuals.”
Many social animals live in environmental conditions where they are not always in visual contact with one another.
Therefore, they could acquire an evolutionary advantage through discriminating between the emotional content of the calls of others from their species, the study says.
In the study, researchers recorded calls of goats which conveyed either positive or negative emotions.
They then played one of these calls through a loudspeaker to another goat, and subsequently exposed it to a variant of the same call type associated with the opposite emotion.
This was followed by a final call which was randomly selected.