Animals fall into prolonged bad moods over minor slights in the same way as humans, scientists have discovered.
A new study, which promises to transform the understanding of animal psychology, found that birds, rats, fish – and everything in between – can be far less pragmatically minded than previously thought.
Researchers have long assumed that animals’ emotional state principally reflects how well or badly they are managing to achieve life’s core priorities: in essence keeping safe, keeping fed, and reproducing.
It was thought that where a creature appeared gloomy, that was likely to be because they are faring badly against one of these essential goals.
Now, however, a new analysis has found that it could be just as likely that the animal is suffering from what amounts to a lengthy strop provoked by a previous and unrelated factor.
The reverse is also true.
The team at Queen’s University Belfast gave examples of starlings with more comfortable nests appearing more upbeat in the face of temporal stresses compared with those with less commodious homes.
They also pointed to honeybees having a more pessimistic reaction to smells if they have previously received a fright.
The scientists draw on a theory of “contests” between animals, interactions where two or more organisms are competing for the same core advantage.
While the significance of any particular contest may be small, the outcome can affect an animal’s mood long-term, the new study found.
Dr Andrew Crump, postdoctoral researcher from the School of Biological Sciences at Queen’s and Lead Author of the paper, said: “Human emotion influences unrelated cognition and behaviour.
“For example, people rate their overall life satisfaction higher on sunny days than rainy days.
“We have found that animals’ emotions also influence unrelated cognition and behaviour.
“For example, animals that won a contest experienced a more positive mood and expected fewer predators in their environment.
“Similarly, animals that lost a contest experienced negative emotions and took part in less future contests. These carryover effects may lead to maladaptive behaviour.”
Using case studies, the researchers suggest that just as depressed or anxious humans are more pessimistic about the future, animals that lose fights will be in a more negative emotional state, more pessimistic about whether they can win, and so are less willing to engage in future fights.
“Stimuli or events that elicit emotional responses might influence virtually any decision, potentially with life-or-death consequences,” said Dr Crump.
“For example, are rustling leaves a predator or the wind? Anxious animals will probably interpret the rustling as a predator and run away.
“This mood is adaptive when the anxiety is relevant, for example, if it was induced by previous experience of predator attacks.
“But the mood is maladaptive if it was induced by something else, say, losing a contest.”
Emotions in animals can be measured empirically through changes to cognition, how much energy and drive a creature shows, and nervous system activity.
Dr Gareth Arnott, senior lecturer from the School of Biological Sciences and Principal Investigator on the paper, said currently animal behaviour researchers typically do not consider animal emotions in their work.
“The results of this study show that this may need to be considered as the role of animals’ emotion is crucial in relation to understanding their subsequent behaviour,” he said.
Telegraph Media Group Limited