Bumblebees’ ability to solve puzzles suggests a capacity for animal culture: NPR

A new study shows that bumblebees can learn to solve puzzles from each other.

Christopher Furlong/Getty Images

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Christopher Furlong/Getty Images

A new study shows that bumblebees can learn to solve puzzles from each other.

Christopher Furlong/Getty Images

The next time you’re having trouble solving a tricky puzzle, consider asking a nearby bumble bee.

A new study in the journal PLOS Biology finds that these humble insects can actually learn to solve puzzles from each other, 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 few decades, a growing body of evidence has accumulated to show that animals such as chimpanzees and birds show signs of culture, “by which we really mean that animals learn from each other,” says Andy Whiten, a cognitive ethologist who studies wild animal mind at the University of St Andrews in Scotland. This learning can range from navigating a tree route to using a tool to access a particular food item.

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

This behavior tends to be passed down from one generation to the next. It’s the same with people. Some of us learn from more experienced people how to make matzo ball soup or dance merengue, and then we pass it on to our children.

Whiten compares culture to another, more flexible form of inheritance.

Bridges agrees. “It actually works 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 for a species, and it seems to be increasingly common in the animal kingdom, Bridges wondered if bumblebees might have a capacity for it.

“No one has really thought to look at it in invertebrates before,” she says. Not even in bumble bees, 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 they are mostly driven by innate factors.”

Bridges set out to prove them wrong.

To study bumble bee culture in the lab, she first had to train a few diligent bees to perform a new behavior. She chose to solve a puzzle box.

“But trying to design this box was kind of crazy because bees are really, really smart, sometimes frustrating,” Bridges explains. “They’re always looking for a more efficient solution, and it’s always not going to be the one you want.”

This puzzle box was created for bumble bees to solve
This puzzle box was created for bumble bees to solve

The bees always “hacked” the puzzle by, for example, squeezing through unintended holes in the device to reach the tasty prize inside.

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

“I basically built it out of petri dishes,” she says triumphantly. The base of the petri dish held the reward: a drop of super-sweet sugar water. Bridges cuts a small hole in the lid “to form a rotating top that can be rotated by pushing either this red tab clockwise or the blue tab counterclockwise.”

She trained some bees to hit the red tab to get the sugar water and trained others to press the blue tab. Then Bridges placed these teacher bees in different colonies along with the puzzle boxes.

It wasn’t all fun and games: fiddling with all these bees resulted in Bridges being stung several times. The fourth sting sent her to the hospital with anaphylaxis.

“So I had to wear a vest 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 eventually played out. In colonies where the tutor bee had initially 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 flag, their fellow bees tended to do the same.

“We found that the behavior spread among the colonies,” she says. “They copied the behavior of the protesters, even when they occasionally discovered that they could do the alternative.”

In the control colonies, where there were no teachers, the bees sometimes learned 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 (may have) not understood what they had done, or they hadn’t quite made the connection between their behavior and the reward.”

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

“We were taught that a lot of insect behavior was kind of hard-wired,” says Jessica Ware, an entomologist at the American Museum of Natural History who was not involved in the research. “And what this magazine does is kind of turn it on its head. I mean, who knows what grasshoppers are capable of—or the humble cockroach.”

Because bumble bee colonies collapse before winter, there is little chance that a tradition can be passed down from generation to generation. So Bridges plans future work with insects that live in colonies that last for years, like stinging bees.

Of course, insect culture may look somewhat different from the culture seen among other animals, especially humans. It’s a matter of degree, says Whiten, who was also not part of the study. “Cultures vary enormously across species in ways that I think have different implications for the complexity of brains involved,” he says.

Still, Bridges argues that her work with bumblebees shows that culture might not be so unusual.

“Maybe it doesn’t require very, very complex cognitive mechanisms,” she says. “Maybe it’s not some peak 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 quite special … because we have culture and we can learn and we are social,” she says. But now that “it turns out that even the bee also has culture, it’s an uncomfortable truth.”

That truth, Whiten summarizes, is that “everything we’ve discovered about animal culture means that human culture, once thought to be unique,” he says, “did not appear ‘out of the blue’ but has evidently built on deep evolutionary basis.”

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