Vol. 23, Issue 1: Fall 2015

The Giggle Gene: Are Our Genes Making Us Laugh?

Isabel Marchand

Long has the question been asked if there is a link between genes and personalities. Due to the joint efforts of researchers at the University of California, Berkeley and Northwestern University, including Robert Levenson and Dacher Keltner of UC Berkeley and Claudia M. Haase of Northwestern, the existence of a “laughing gene” in the human genome was discovered in 2015. Individuals in the study possessing the short version of a specific gene, known as 5-HTTLPR, were more likely to smile or laugh than those with the longer version of the gene. This discovery may offer insight into the interaction between our genes and our responses to the environment.

The relationship between genes and personality has perplexed scientists for quite some time. Until now, very little was known about the relationship between genetics and personality. However, the discovery of this link between 5-HTTLPR and emotional responses may change that. The findings associating a short 5-HTTLPR allele with positive emotions refutes prior research that asserted this same allele caused more somber emotions in certain individuals. Prior to this study, the neurotransmitter 5-HTTLPR was thought to create feelings of depression and anxiety, in addition to some degree of Post-traumatic Stress Disorder. Occasionally, it has even been referred to as the “depression gene.”

In this experiment, three different groups of individuals watched different scenarios that would evoke both positive and negative emotional responses. Over three hundred individuals participated in this study. The first group of young adults watched cartoons, the second group watched a more subtly comical movie, while the third group watched a martial conflict unfold. The researchers filmed the test subjects and then tested the recordings with a decoding system that observed and recorded the emotional microexpressions of participants. These microexpressions, which we make subconsciously in response to emotional situations, reveals what emotions we are feeling. The researchers wanted individuals to express genuine emotion. The most important clue for this is engagement of the eye muscles responsible for creating “crow’s feet.” If an individual’s smile or laugh was accompanied with crow’s feet, the researchers knew it was a genuine, positive reaction. In addition to recording these microexpressions, the researchers took saliva samples to test for the allele itself.

The findings are ground-breaking in the discipline of psychology. Not only did individuals possessing the short 5-HTTLPR allele show more genuine positive emotion, but these results held true even after taking into account gender, race, and ethnicity—strengthening the argument that this allele and its effects are present in the entire human genome. This new research argues that individuals with this short 5-HTTLPR allele are not simply more predisposed to negative emotional reactivity, like originally thought, but are rather more likely to feel the emotional highs and lows of life as a whole. In other words, individuals with the short allele are more likely to experience the extremes of the emotional spectrum, while those with the long-allele are less likely to react in such drastic ways.

It is important to note that this research may indicate a link between genes and personality, but it does not mean that there is necessarily a causal relationship between the two. Further research would need to be conducted in order to test if the alleles themselves are solely responsible for evoking emotional responses to stimuli. Different upbringings and other personality contributors could also be responsible for our varied emotional responses. Hopefully, though, this study can lead researchers to eventually determine whether this cause and effect relationship does exist . treated as such.

About the Author

Isabel Marchand is currently a second year Molecular Environmental Biology major in the College of Natural Resources and plans to pursue a career in either medicine or environmental health.