Ever feel a buzz of happiness? Whether insects can feel emotion might sound crazy, but it’s the subject of scientific debate at the moment because, well, it just might be that they do.
While a majority of recent studies have focused on negative insect emotions, a team led by Clint Perry at Queen Mary University in London, UK examined the potential for bumblebees to feel happiness.
Because bees can’t answer a questionnaire about levels of contentment, the researchers devised a series of experiments to test how the insects’ decision-making might be affected by positive emotions induced by a trigger familiar to most of us.
“In humans, consumption of sweet snacks can induce positive emotions,” the researchers write in their paper published in Science.
“Here we examine whether consuming a small amount of sucrose solution before performing a test causes bumblebees (Bombus terrestris) to behave in a way that is indicative of an induced positive emotion-like state.”
The experiment is based on the finding that emotional state can change a person’s decision-making process in the face of an ambiguous situation – that is, a happier person will make a more optimistic judgement than an unhappy person.
For this experiment, bees were trained to expect a sugar solution beneath a blue cylinder to the left of an arena while a green cylinder to the right held only water.
Once trained, the insects would make a bee-line – pardon the pun – for the sugar solution, while the water was approached slowly, if at all.
The bees were then introduced to an ambiguous cylinder – one with turquoise marking, smack-bang in the centre of the arena.
Half the bees were given a sugar hit before they entered the test while the other half was not.
Bees that were given a taste of sugar before entering the arena were much quicker to explore the ambiguous cylinder than the others, suggesting they had expectations of a positive outcome, according to the researchers.
They then tested whether “happy” bees recovered more quickly from a negative event. Bees were captured, mimicking an ambush by a spider, and released again after three seconds.
The team recorded how long it took each bee to resume foraging after the negative event and, sure enough, those that had a sugar hit beforehand recovered more quickly.
Next, the researchers wanted to hone in on what was causing this emotional state. They repeated their experiment, this time blocking the release of dopamine – the “happy chemical” linked to rewards in humans.
Bees that were given a sugar hit along with dopamine blockers took longer to explore the ambiguous cylinder and bounce back from an attack.
The researchers write their findings are in line with our understanding of how positive emotion-like states affect decision-making in mammals, including humans: “Our results lend support to the notion that invertebrates have states that fit the criteria defining emotion.”
The team points to an “intriguing prospect” for further research, in which the circuits controlling hunger, nutritional valuation and arousal in bees could impact their decision-making or resilience.
Amy Middleton is a Melbourne-based journalist.
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