Illustration of species Apodemus semotus (image: Shingo Sakuma,1941/Wikimedia)

Hanging out a lot with the same crowd can make immune systems of individual animals similar, even if the crowd is not related. That’s according to a recent paper in Science Advances that teased out connections between social behaviors and immune cell profiles of lab mice which were allowed to “rewild” and do as they pleased in controlled, predator-free, outdoor enclosures.

SFI External Professor Andrea Graham (Princeton University) and coauthors carefully tracked the behaviors of mice from three inbred strains, including their socializing with other mice, to see how it correlated to their immune systems’ T and B cell profiles.

They found that the more two mice hung out, the more similar their immune system profiles got. In fact, their immune profiles became even more similar than those of siblings or mice that had been similarly infected. The results highlight the immunological importance of shared spaces and activities, as well as social networks.

Read the paper “Spatiotemporal-social association predicts immunological similarity in rewilded mice” in Science Advances (December 22, 2023) at