Humans live in a right-handed world. Estimates vary, but some 75 to 90 percent of us use our right hands as our “write hands.” If our species has dominant sides, it begs the question: How common is this trait across the animal kingdom? Are our near-cousins, like chimpanzees, right-handed or left-handed? And what about animals like whales that don’t even have hands? If an octopus had to high-five, which tentacle would it use?
For many years, scientists thought that handedness was unique to humans. But according to a growing body of research, many animals do have a preferred hand, limb, or even tentacle, and it likely starts in the brain.
“As soon as you have two sides of the brain, they start task-dividing,” says Ruth Byrne, a biologist who’s studied handedness in octopuses.
