Why do animals differ in personality? Researchers at LiU used human drugs that alter two brain chemicals, serotonin and dopamine, to see if these drugs would change the behavior of animals. Take a closer look at the crickets used in the study, in the video below.

Individuals in many animal species show different personality types. Some individuals are for example consistently bolder than others. Robin Abbey-Lee, postdoctoral researcher (photo from video).

“However, in biology, we still do not fully understand what causes people or animals to show differences in personality. In humans, people with different levels of brain chemicals, such as serotonin and dopamine, often behave differently. However, we do not know if these chemicals can explain personality differences also in other species, and if the chemicals are causing the observed differences or if both the differences in behavior and chemical levels are caused by another underlying factor”, says Robin Abbey-Lee, postdoctoral researcher at the Department of Physics, Chemistry and Biology, IFM, and lead author of the study.

The researchers, therefore, set out to experimentally change the levels of the brain chemicals serotonin and dopamine in the crickets. They did that by giving the crickets human pharmaceuticals that are known to act on the dopamine and serotonin systems and are used to treat Parkinson disease and depression, respectively. Hanne Løvlie Photo credit Anna Nilsen

“In this study we wanted to really address an important gap in our knowledge by experimentally altering these brain chemicals and seeing if we could get a resulting behavioral change”, says Hanne Løvlie, associate professor at IFM, and senior author.

What the researchers found was that changing the serotonin levels made crickets less active and less aggressive. But changing the dopamine levels of crickets did not change their behavior.

“This suggest that serotonin has a clearer underlying role in these behaviors”, says Hanne Løvlie.

These results both improve our understanding of why animals have personality, and also raise the issue of how increasing levels of pharmaceuticals leaking into nature through our waste water may affect animals.

The study is published in Scientific Reports.



The article: ”Experimental manipulation of monoamine levels alters personality in crickets”, Robin N Abbey-Lee, Emily J Uhrig, Laura Garnham, Kristoffer Lundgren, Sarah Child and Hanne Løvlie, (2018), Scientific Reports, published online 1 November 2018, doi: 10.1038/s41598-018-34519-z