In numerous species, individuals vary in cognition, but why is still unclear. A group of researchers at the Department of Physics, Chemistry and Biology (IFM) at Linköping University explored cognitive variation in red junglefowl. They hypothesised that variation in dopaminergic and serotonergic genes would help explain individual variation in cognition. For instance, why some individuals are more optimistic than others.
So why red junglefowl?
— We have studied cognition of red junglefowl, the ancestor of our domestic fowl, for many years now. These birds are ideal for cognitive studies, as they are easily habituated to human handling and more than happy to work for food rewards. We always find individual differences in cognition, for example, in optimism, which enables us to investigate why this is, says Hanne Løvlie.
Photo credit Sam HurencampBut how can one scientifically measure how optimistic an animal is?
— If an animal learns that it is rewarded for approaching one cue, for example, a white card, but not for approaching another, for example, a black card, we can decipher their optimism from how they respond to a cue that is ambiguous between the two, for example, a grey card. If they approach the grey card quickly, this shows they are expecting a reward, that is, they are optimistic, explains Laura Garnham, a PhD student in Hanne Løvlie’s research group, who worked on the study.
Why investigate if variation in dopaminergic and serotonergic genes explain variation in optimism?
— The dopaminergic and serotonergic systems are often linked to behaviour and cognition. Therefore, we predicted that genes from these systems could play an important role in determining variation in optimism in our red junglefowl, says Clara Gómez Dunlop, together with Robert Boddington, who is one of the main authors of the study.
Dopaminergic and serotoninergic system genes turned out to be important pieces of the puzzle for understanding junglefowl cognition.
— Our results indicated that variation in gene expression in these systems underlies variation in cognition. In terms of optimism, one of our dopaminergic genes was positively correlated, while one of our serotonergic genes was negative correlated, with optimism. As individuals differ in expression of these genes, this helps explain why some are more optimistic than others. We also found connections between dopaminergic and serotonergic genes and cognitive flexibility, that is, how quickly the birds could unlearn one thing and learn something new. Overall, our results help improve our understanding of animal cognition. Dopamine and serotonin influence cognition in humans also, so our results point to similarities in cognition between human and non-human animals, summarises Hanne Løvlie.