Kate McGrath, SUNY Oneonta – Facial Asymmetry in Gorillas Can Be A Sign of Stress

On SUNY Oneonta Week:  Stress in childhood can alter the shape of your face.

Kate McGrath, assistant professor of biological anthropology, discusses why.

Kate McGrath studies indicators of stress preserved in the skulls and teeth of great apes. She has done fieldwork in Rwanda, Kenya, and Tanzania at fossil sites and in national parks. Dr. McGrath studied anthropology and geology as an undergrad at the College of Charleston, and from 2011-2012, she worked full time as an imaging specialist at the Smithsonian’s National Museum of Natural History. She regularly engages in science outreach with kids and the public at K-12 schools and museums. She uses blogging, social media, and public outreach to make science more inclusive and accessible.

Facial Asymmetry in Gorillas Can Be A Sign of Stress

Have you ever used a filter to make your face perfectly symmetrical? Facial symmetry is often considered to be a sign of beauty. But one thing most of us don’t realize is that facial asymmetry can be a sign of stress during development.

Studies of lab animals like flies and rodents have found that facial asymmetry is related to developing in a stressful environment, and/or to being inbred. In our recent study, we analyzed gorillas, our second closest living relatives, to figure out which factor was more likely to contribute to facial asymmetry: inbreeding or early life stress.

One species we studied – mountain gorillas – are endangered with only around 1,000 individuals alive today. They are more inbred than even the most inbred human populations. But, we expect them to have less stressful early lives compared to other gorillas because they primarily eat plants that are available all year long.

This is in stark contrast to western lowland gorillas, the kind that you see in zoos. They are much less inbred, but in the wild, they like to eat seasonal fruits, which are in short supply at different times of the year. So, for our study, we predicted that they might experience more stressful early life environments as a result.

Our studies showed that mountain gorillas, the very inbred species, have the most asymmetric faces by far. One important consideration is that inbreeding makes individuals more susceptible to everyday stressors. If future studies continue to support the relationship between inbreeding and asymmetry, it might help to explain why people prefer symmetric faces over asymmetric ones. From an evolutionary perspective, it’s a good idea to mate with people who are not inbred, so asymmetric faces might act as a kind of warning sign.