Can insects have culture? Puzzle-solving bumblebees show it's possible

Next time you're having trouble solving a tricky puzzle, consider asking a nearby bumblebee.

A new study in the journal PLOS Biology finds that these humble insects can actually learn to solve puzzles from one another, suggesting that even some invertebrates like these social insects have a capacity for what we humans call "culture."

"These creatures are really quite incredible. They're really, really good at learning despite having these tiny, tiny brains," says Alice Bridges, a behavioral ecologist at Anglia Ruskin University in England.

In the past couple of decades, a growing body of evidence has accumulated to show that animals like chimps and birds show evidence of culture, "by which we really mean just that animals learn from each other," says Andy Whiten, a cognitive ethologist who studies wild animal minds at the University of St Andrews in Scotland. This learning can range from navigating a migratory route to using a tool to access a particular food.

"If what they learn lasts for a long time," says Whiten, "then we might be prepared to call it a tradition. And culture is made up of multiple traditions."

These behaviors tend to be passed down from one generation to the next. It's the same thing with humans. Some of us learn from more experienced individuals how to make matzo ball soup or dance the merengue, and then we pass that down to our children.

Whiten likens culture to a second, more flexible form of inheritance.

Bridges agrees. "It actually functions much faster" than genetic inheritance, she says, "because you can learn a new behavior to overcome a problem from someone else."

Since culture can be incredibly useful to a species and it seems to be increasingly common across the animal kingdom, Bridges wondered whether bumblebees might have a capacity for it.

"Nobody's really thought to look at it in invertebrates before," she says. Not even in bumblebees, which are social insects that spend a lot of time together. "They have some of the most intricate, complex behavioral repertoires in the animal kingdom. Yet people assume that they're mostly driven by innate factors."

Bridges set out to prove them wrong.

To study culture in bumblebees in the lab, she first had to train a few industrious bees to perform a novel behavior. She opted for solving a puzzle box.

"But trying to design this box was kind of crazy because bees are really, really smart, sometimes frustratingly so," Bridges explains. "They're always looking for a more efficient solution and invariably it won't be the one that you want."

The bees were always "hacking" the puzzle by, for example, squeezing through unintended gaps in the device to reach the tasty prize inside.

Finally, Bridges landed on a design the bees had to play straight. She holds up the result.

"Basically, I built it out of Petri dishes," she says, triumphant. The base of the Petri dish held the reward: a drop of super sweet sugar water. Bridges cut a small hole in the lid "to form a rotating top that can be spun by pushing either on this red tab clockwise or the blue tab anti-clockwise."

She trained some bees to head-butt the red tab to get the sugar water and trained others to push the blue tab. Then, Bridges placed these tutor bees inside different colonies, along with the puzzle boxes.

It wasn't all fun and games: Fiddling with all these bees resulted in Bridges getting stung multiple times. The fourth sting sent her to the hospital with anaphylaxis.

"So I had to wear a bee suit after that during a heat wave to do the experiments, which was miserable," she chuckles. "I used to put a little electronic fan inside the hood."

Bridges persevered, however, and the experiment ultimately played itself out. In colonies where the tutor bee had originally learned to push the red tab, the other bees in the colony usually pushed the red tab. In colonies where the tutor bee was trained to push the blue tab, their fellow bees tended to do the same.

"We found that the behaviors spread among the colonies," she says. "They copied the demonstrators' behavior even when occasionally they discovered that they could do the alternative."

In the control colonies where there were no tutors, the bees sometimes learned how to open the boxes, but never as efficiently or reliably. "Most of them would do it once or twice and then never again," Bridges explains. "They perhaps [had] not understood what they had done or they hadn't quite made the link between their behavior and the reward."

The conclusion, Bridges and her colleagues at Queen Mary University report in their new study out today, is that bumblebees can transmit certain behaviors — culturally.

"We were taught that a lot of insect behavior was kind of hardwired," says Jessica Ware, an entomologist at the American Museum of Natural History who wasn't involved in the research. "And what this paper does is kind of turn that on its head. I mean, who knows what grasshoppers are capable of doing — or the lowly cockroach."

Because bumblebee colonies collapse before winter, there's little chance a tradition could get passed down from generation to generation. So Bridges is planning future work on insects that live in colonies that last for years, like stingless bees.

Of course, insect culture might look rather different from the culture seen among other animals, particularly humans. It's a question of degree, says Whiten, who wasn't a part of the study either. "Cultures vary enormously across species in ways which I think have different implications for the complexity of brains that are involved," he says.

Still, Bridges argues that her work with bumblebees shows that perhaps culture isn't that unusual.

"Maybe it doesn't require very, very complex cognitive mechanisms," she says. "Maybe it's not some pinnacle of cognition that only a few species have. Maybe it's actually very widespread."

Ware agrees.

"Many of us consider ourselves and our fellow primates to be rather special... because we have culture and we can learn and we're social," she says. But now that "it turns out even the bee also has culture, that is an uncomfortable truth."

That truth, summarizes Whiten, is that "all we have discovered about animal culture means that human culture, once thought unique," he says, "did not emerge 'out of the blue' but has obviously built on deep evolutionary foundations." [Copyright 2023 NPR]