Many people view loners and introverts with a sense of suspicion, thinking it odd they chose a solo life. However, according to Corina Tarnita, an associate professor of ecology and evolutionary biology, loners exist across many species including those that travel in herds and swarms. In fact, even in plant life and mold, you can find single “beings” intent on leading a life away from the rest. According to Princeton researchers, there’s a very good reason for this and it has to do with survival. (1)

An Evolutionary Insurance Plan

The Princeton team’s goal was to show that loners are devised by nature as an “evolutionary insurance plan.” Loners diversify their species’ genetic portfolio not to go against collective behavior, but instead to ensure its survival. (1)

In order to prove their theory, they had to demonstrate it was a choice to lead a loner’s life, not some other form of natural selection. The Princeton team decided that the cellular slime mold, Dictyostelium discoideum would help them prove there is such a thing as loner behavior, even in this simple life form. (1)

“I was at a conference, and a speaker was showing videos of slime molds doing this very complex collective behavior, all determined to reach the center of aggregation,” says Tarnita. “All but some, I noticed: Here and there, some scattered cells on the plate just didn’t seem to react at all to this aggregation process.” While the speaker at the conference dismissed these anomalies as “mistakes,” Tarnita was intrigued. (1)

Testing For Flaws

Tarnita approached Allyson Sgro, a postdoctoral researcher in the lab of Thomas Gregor at the time. They “started to poke at the loners a little bit” and then tested them for flaws. Nothing was “wrong” with them. They behaved like other cells other than the fact they resisted the need to assemble into the reproductive tower-like other mold cells. (1)

Tarnita and her co-authors Sgro and Ricardo Martinez-Garcia, theorized it was possible some of these loners served a purpose. They could take advantage of resources in the environment while their counterparts were busy. After a few years of study, Fernando Rossine joined the group and mastered a system. (1)

Loners Part Of The Process

He determined the slime mold loners were “part of the process.” In fact, 30% chose the role of loner. Rossine then also discovered that Tarnita’s hypothesis that loners are not random, but instead a heritable trait, was true. However, he noted the number of loners was dependent on population density. In smaller populations, all cells were loners, while in larger populations the number of loners plateaued. (1)

“This was exhilarating because it meant that we had originally been right that the loners were far from boring, but it also meant that, theoretically, we needed to go back to the drawing board,” says Tarnita. (1)

Species Become Invulnerable

Having loners leaves the species invulnerable to what they would face collectively. A perfect example? COVID-19. While the rest of us are in danger due to our social nature, loners and introverts naturally choose isolation. This reduces their risk for contracting the virus. (1)

However, in the case of the mold, the decision might be collective. “It’s a social bet-hedging,” says Rossine. “And a fascinating conclusion that follows from our findings is that, at least for slime molds, the decision not to become part of the collective is, in fact, taken collectively. All the cells kind of talk to each other chemically: ‘Oh, you’re going? I guess I’m staying.’ There’s communication involved in becoming a loner.” (1)