Bumblebees go out of their way to play
All work and no play makes Jack a dull boy. That proverb says we should go out of our way to enjoy something other than work, in order to grow as humans and improve our well-being. Animals can sometimes be seen playing, and their "work" might be seen as foraging for food or simply surviving. A recent study suggests that even the hardworking bumblebee falls into that category.
Why do people (and animals) play?
The German playwright and philosopher Friedrich Schiller noted in the 1790s, "Traces of play can be found in nature whenever there is an abundance of resources: lions play when they have excess energy and are not under threat." Another German researcher Herbert Spencer proposed in the 1800s a "surplus energy theory" similar to Schiller's. Spencer said a "child's playing (jumping, climbing, running, etc.) was a manifestation of his inner energy, and he compares humans to animals, saying animals "generally use their energy for survival but children are provided for, resulting in an energy surplus which is rechannelled into play." In his book The Play of Animals (1898), German philosopher and psychologist Karl Groos pointed out a biological significance of playing is unavoidable in the young: "the very existence of youth is due in part to the necessity for play; the animal does not play because he is young, he has a period of youth because he must play."
Groos broke down animal playing into the following categories:
- movement play (like fireflies flitting about, and insects swarming, both for no apparent reason)
- hunting play (literally playing with one's food before the animal finally kills and eats it)
- fighting play (like one animal provoking another even though the other had no thoughts to fight, or just playful mock fighting)
- artistic play (why else would birds take shiny objects back to their nests?)
- nursing play (monkeys adopting dolls, one animal species caring for another)
- imitative play (primates copying humans' use of tools; dogs howling to music; chicks copying parent bird singing)
Do bees fall into any of these categories, and do they play at all? Researchers at the Queen Mary University of London noticed that bees played with plastic-coated wooden balls 1.5 cm (0.6 inches) in diameter. Some were colored yellow or blue, and some had their original white color. Bees can see the difference in yellow and blue.
Experiment 1 set up a nest of bees on the right with a tunnel to the play room. One side had balls stuck to the floor, and the other side had balls which could roll. Past that was a room with sugar water and pollen. So, they could stay with the nest or just eat or interact with the balls.
They found that bees played with balls that could move more than those that were stuck to the floor. The average time they spent was 0.4-31 seconds, and the rolling distances were 2-601 mm (0.07-24.00 inches).
In experiment 2, they compared young bees (less than 3 days old) to older bees (more than 10 days old). They chose these ages because peak ball-rolling activity was seen earlier with bees 3-9 days old. The test room now had only balls that could move. The younger bees rolled more balls than the older ones. Also, the speed that they moved the balls was no different whether bees were young or old. Younger ones just did more.
Was this playing, or were they forced to participate? The researchers calculated that after first exposure to the balls, bees were more likely to seek out the balls that moved. So, they found an interest in them more than immovable balls.
Since food was available at any time, how much time did bees spend foraging for that compared to playing? They noted that there was a peak in playing at the younger ages for males and females, and then it tapered off. Foraging for food was fairly constant regardless of age, but females did more than males. Younger males did far more playing than foraging, while young females spent about the same time doing each. Later, the amount of playing decreased significantly for both, but looking for food did not seem to change. The researchers stated, "These results suggest that bees had a different motivation to move objects compared to that of foraging."
But what if the setup had no balls in the play chamber between the nest and food? Would bees go into it intending to play, or would they avoid it? The researchers set up two play chambers, one yellow and one blue, with baffles in front of them to block their view of what was inside. Sometimes the blue chamber had balls, sometimes the yellow one did.
Gordon Burghardt from the University of Tennessee wrote a book The Genesis of Animal Play: Testing the Limits. In it, he covered aspects of many animals at play and came up with 5 criteria for actions that must be met in order for us to classify them as play:
- Play is voluntary, spontaneous or rewarding in and of itself
- The behavior should not require an association with another reward (e.g. food) to be performed
- Play behavior should differ from functional behavior; the motor actions are different from those used, for example, when searching for food or attempting to mate
- Play is repeated, but must be separated from one-off chance occurrences and habitual ticks that repeat the same patterns over and over
- Play is understood to be a pleasant phenomenon initiated when an animal is in a relaxed state, not induced by stress like some animals show when cooped up in cages.
The bees in this report seem to fit all of the criteria. Bees play!
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