I'm right-handed. This fact makes it easier for me than for lefties to push revolving doors and play the accordion, though not at the same time. Our societal infrastructure is set up for righties, the result of (or perhaps a continuing cause for) only about 10 percent of humanity being left-handed.
It's actually the brain's infrastructure that seems to be mostly responsible for almost all of us being righties. A 2009 paper in Philosophical Transactions of the Royal Society B notes: “Lateralization of brain and behaviour refers to the fact that the hemispheres of the brain differentially control behaviour.... At the behavioural level, it is often expressed in side biases for motor output, perception and information processing.”
Chimps show a slight tendency toward right-sidedness but much less than our 9:1 ratio. Horses can have a preferred side, which is complicated by that pesky extra set of legs in the back. A 2016 article in the publication The Northwest Horse Source explains that most mounts are “‘right front-left hind horses.’ They generally are a little more comfortable ... turning to the left.” (You know what you call a Thoroughbred that doesn't like to turn left? A loser. In the U.S. anyway, where races are counterclockwise.)
A 2015 study in Current Biology looked at seven marsupial species and found that the ones that walked on all fours lacked a conspicuous sidedness. But the bipedal bouncers, such as kangaroos and to a lesser extent wallabies, did have a preference—and they're mostly lefties. (Listen, it's Australia. The fact that a large, upright, hopping, pouch-bearing herbivore happens to be predominantly left-handed is unremarkable when you consider that in 1932 the Royal Australian Artillery lost a war against emus. Flightless birds. Search online for “The Great Emu War” if you think I'm lying.)
Despite all these examples of laterality, it still came as a surprise last November when a study found that some bees exhibited handedness when they had to run an obstacle course. By “run” I mean “fly,” and by “handedness” I mean what the authors of the paper in the journal PLOS ONE meant when they entitled it “Obstacle Traversal and Route Choice in Flying Honeybees: Evidence for Individual Handedness.”
Actually the new study cited a 2001 paper in the Journal of Insect Behavior that found that “foraging bumblebees display handedness and tend to rotate in the same direction on successive inflorescences.” So we already knew that bumblebees exhibited a sidedness when they landed on flowers. Now we know they're sided when they fly, too. (Honeybees are also excellent dancers.)
For this study, researchers coerced 102 bees to fly together through a tunnel to get to a sucrose solution, much like how you have to negotiate a hotel corridor to get to the soda machine. Except that at the halfway mark of the bee's tunnel was a barrier with two holes in it. Should your hotel corridor include a barrier with holes in it, go back to your room and strongly consider moving to another hotel.
When the two holes were the same size, about half the bees went through each hole. When one hole was bigger than the other, more bees used the bigger hole. But some flying bees stood their ground. For example, when the smaller hole was on the right side of the barrier, a truly committed righty would even land and wait to walk through the smaller hole rather than use the bigger opposite-side opening, much as a truly committed lefty still thinks Bernie would have won.
The researchers interpreted the results laterally and found that about 45 percent of the bees had a side preference, split evenly between right and left. The distribution of sidedness may help a colony fly efficiently through dense foliage—that some members insist on using smaller gaps could put an upper size limit on the group using the larger space. Thus keeping them from bumbling.