The emergent complexity of ant societies is one of the most fascinating phenomena in the natural world: how do these tiny creatures form such intricate social networks? These networks are so nuanced that the colony itself is sometimes referred to as an organism—or “superorganism”—in its own right, with individual ants as its component parts.

As the paper points out, negative outcomes of social contagion are strikingly rare amongst ants, suggesting that that reverse social contagion plays an important role in ant societies. To quantify how reverse social contagion regulates ant behavior, the researchers examined individual ant activity amongst 12 colonies of harvester ants. These colonies varied in size from several dozen ants to several hundred. The experiment set out to determine how the size of a colony influenced the activity level of its workers: if ant behavior depended only on positive social contagion, more ants would be expected to be active in a larger colony, as they would have more opportunities to observe a given behavior in their fellow ants.

The study found that just because the colony was larger, did not mean that more ants were exhibiting the same behavior. Because different groups engaged in a variety of behaviors, observations suggest that reverse social contagion was also at play.

This also forms a stark contrast to human societies, where the level of individuals’ activity tends to increase more quickly as a society’s population grows. The announcement accompanying the paper uses the general example of food gathering to illustrate the difference: if an ant sees multiple fellow workers gathering food, it saves its own energy for another task that might be more beneficial to the colony. If a human sees their neighbors all gathering food, however, they worry there might be none left for them—a worry that tends to become more pressing as population increases.