Have you ever found yourself zoning out during a long work day and feel that you’re not getting anything done while those around you are hustling and bustling non-stop? It seems like something only humans would go through, but it turns out we’re not alone.
Ants have an incredible reputation as being some of the hardest working creatures in the animal kingdom. It takes hundreds, if not thousands, of ants working together to build a nest, and it usually gets done in impressive time. Looking at a group of ants, it might look like they’re all active and pitching in, but scientists have found out that nearly half of them really aren’t doing anything at all.
Daniel Charbonneau of the University of Arizona became interested in how ant colonies work, and decided to create a study to see how efficient all ants were. Charbonneau painted the ants with unique colors to help them stand out, and tracked their movements while building colonies. What he found was a bit of a surprise, with around 40 percent of the worker ants not chipping in. So what were the ants doing exactly?
“They really just sit there,” Charbonneau said. “And whenever they’re doing anything other than doing nothing, they do chores around the nest, like a bit of brood care here or grooming another worker there.” That’s not the only purpose that these “lazy” ants serve, though, and there’s a bit of a dark side to it. Charbonneau explained that the abdomens of the lazier ants were more distended than the others, meaning they had eaten much more before the colony started to build a nest.
It wasn’t easy for Charbonneau to set up the study, as he had to apply very small dots of paint to every single ant. “One on (the) head, one on (the) thorax, and two dots on (the) abdomen,” he explained. “The combination of colors and location identifies each individual, so we can track it in our recordings.”
Charbonneau theorized that the lazy ants might actually be used as a food supply if the worker ants are starving and have to turn to cannibalism. In a lighter hypothesis, Charbonneau says that the ants might be making a sort of wall for protection so that the working ants aren’t attacked or washed out by excessive water. They might even be reserves for if the worker ants can no longer perform their task, ready to step in at a moment’s notice.
There was even a separate experiment conducted by Charbonneau and his team to see how effective the lazy ants could be when needed. The researchers removed 20 percent of the active worker ants to see if the lazy ones would pick up the slack. It turned out they were ready for action, and were quite effective. “Serving as a replacement workforce is a long-held suspicion about the function of lazy ants,” said researcher Anna Dornhaus. “But it was just an assumption and never had been empirically confirmed (before).”
In some of their other studies, the lazy ants continued to be, well, lazy when some of the workers were removed, leading the team to come up with more questions than they had when starting. The team said that “This makes sense because without foraging and brood care, workers and brood won’t be fed, which will likely incur a large fitness cost to the colony very quickly. Thus, it seems that colonies do not seek to maintain homeostasis of colony activity in general, but rather that worker replacement depends on the immediate necessity of the task.”
The next step for Charbonneau is to study ants in the wild instead of in a controlled atmosphere. “We don’t know how quickly their populations turn over in their natural habitat,” he said, “but it doesn’t take much for a colony to lose a bunch of workers. Since they can live for up to five years or more, they have to overwinter, and being snowed in claims many workers each season.” This could be another reason why some ants are larger, as they would be more able to survive throughout the winter with a larger mass and become workers eventually.
Charbonneau concluded by saying “My speculation is this: Since young workers start out as the most vulnerable members of the colony, it makes sense for them to lay low and be inactive…When the colony loses workers, it makes sense to replace them with those ants that are not already busy pursuing other tasks.” In the end, ants have a very similar synergy when it comes to efficiency in the workplace just like humans, so maybe we’re not so different after all.