Happy Bees: Bumblebees Show Dopamine-Based Positive Emotions
Research suggests that after eating a sugary treat, bees display optimism.
Posted November 3, 2016
All sorts of bees are amazing beings (no pun intended). It's been known for a while that honeybees can become pessimistic after being agitated, and now researchers report that bumblebees display positive emotions. Needless to say, this research has attracted broad global attention in popular media, and good summaries can be read in Emily Underwood's essay called "Primitive signs of emotions spotted in sugar-buzzed bumblebees," Virginia Morell's piece "Don’t worry, bees are happy," and Michael Mendl and Elizabeth Paul's short note aptly called "Bee Happy." These essays are based on a research paper by Clint J. Perry, Luigi Baciadonna, and Lars Chittka titled "Unexpected rewards induce dopamine-dependent positive emotion–like state changes in bumblebees" published in the prestigious journal Science. The abstract for this essay reads:
Whether invertebrates exhibit positive emotion–like states and what mechanisms underlie such states remain poorly understood. We demonstrate that bumblebees exhibit dopamine-dependent positive emotion–like states across behavioral contexts. After training with one rewarding and one unrewarding cue, bees that received pretest sucrose responded in a positive manner toward ambiguous cues. In a second experiment, pretest consumption of sucrose solution resulted in a shorter time to reinitiate foraging after a simulated predator attack. These behavioral changes were abolished with topical application of the dopamine antagonist fluphenazine. Further experiments established that pretest sucrose does not simply cause bees to become more exploratory. Our findings present a new opportunity for understanding the fundamental neural elements of emotions and may alter the view of how emotion states affect decision-making in animals.
Ms. Underwood begins her essay, "To human observers, bumblebees sipping nectar from flowers appear cheerful. It turns out that the insects may actually enjoy their work. A new study suggests that bees experience a 'happy' buzz after receiving a sugary snack, although it’s probably not the same joy that humans experience chomping on a candy bar." Drs. Mendl and Paul write, "The authors report decision-making behavior in bumblebees that is analogous to optimism in humans and may reflect positive affect in both humans and other species (6–8). Moreover, the behavior appears to depend on the activity of dopamine, a neurotransmitter involved in the processing of reward in humans." (The numbers refer to references in their essay.)
Summing up the results of this novel and highly significant project, the researchers discovered that after bumblebees learned that a blue flower placard indicated sugary water in a tunnel, and a green flower placard indicated there was no reward, an ambiguous blue-green flower placard was presented to them. The bees spent around 100 seconds before deciding to enter the tunnel indicated by the blue-green placard or to leave. However, when half of the bees were given a sugary treat, they spent about 50 seconds before deciding to check out the tunnel. And, when the action of dopamine was blocked, Ms. Underwood writes, "the effects of the sugar treat disappeared, further suggesting that a change in mood, and not just increased energy, was responsible for the bees’ behavior."
Not all researchers agree with the conclusion that the bees were necessarily experiencing positive emotions, however, we need these sorts of projects to learn more about the taxonomic distribution of emotions across all nonhuman animals.
Please stay tuned for more on the fascinating cognitive and emotional lives of the diverse animals with whom we share our magnificent universe.
Marc Bekoff’s latest books are Jasper’s Story: Saving Moon Bears (with Jill Robinson), Ignoring Nature No More: The Case for Compassionate Conservation, Why Dogs Hump and Bees Get Depressed: The Fascinating Science of Animal Intelligence, Emotions, Friendship, and Conservation, Rewilding Our Hearts: Building Pathways of Compassion and Coexistence, and The Jane Effect: Celebrating Jane Goodall (edited with Dale Peterson). The Animals’ Agenda: Freedom, Compassion, and Coexistence in the Human Age (with Jessica Pierce) will be published in early 2017.