When viruses, parasites and other pathogens spread, humans and other animals tend to hunker down with immediate family and peer groups to avoid outsiders as much as possible. But could these instincts, developed to protect us from illnesses, generalize into avoidance of healthy individuals who simply look, speak or live differently?
Jessica Stephenson, an assistant professor in the University of Pittsburgh Department of Biological Sciences, coauthored a paper exploring the answer, which was recently published in the Proceedings of the Royal Society of London, Series B.
"During epidemics, humans tend to become overly sensitive, so any sort of physical abnormality that somebody has suddenly becomes a potential indicator of infection. We become much more bigoted, we pay way more attention to things that differentiate people from what we perceive as our own phenotype. People who look different from us and sound different from us, which, of course, leads to a lot more xenophobia," said Stephenson, who runs Stephenson Lab of Disease Ecology and Evolutionary Parasitology at Pitt.
One example noted in the study showed that black garden ants exposed to a fungus clustered together in groups much smaller than researchers could predict by chance, which effectively limited the spread of disease. Similar behaviors seen among 19 non-human primate species were also credited for lowering direct spread of parasites.
Human beings share these same biological impulses to separate into modular social groups. However, when pathogens are spreading, humans tend to also adopt a set of behaviors that are "hyper vigilant and particularly error prone," the researchers wrote.
"It's interesting and really disappointing," Stephenson said.
As COVID-19 continues its spread, humans are even more susceptible to the impulse.
"We shouldn't discriminate against different groups in our social distancing, or in our efforts to work together to beat the virus," she said. "But I think our natural, evolved tendencies would be to associate only within our ingroups. We have to fight that natural antipathy towards people who differ from ourselves, and not shut down."
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For more information or to discuss the study with Stephenson, contact dmtodd@pitt.edu.