Are polar bears left-handed? This question has been the source of much debate, but a study published in a recent issue of Biology Letters may have finally given an answer. To untangle this mystery, polar bear biologists from the University of Guelph in Canada compared polar bears' preference for using their right or left paws while performing three different tasks: opening a door, reaching for food behind the door, and resting polar bears' paws under their chins.
To study polar bears' paw preferences in these tasks, researchers used hidden cameras set up near polar bear enclosures at the Assiniboine Park Zoo in Winnipeg, Canada. The cameras captured footage of polar bears passing by the enclosures, and from this footage the researchers could determine which polar bear paw the animals used most often to perform these tasks. One polar bear in particular, an 11-year-old female named Ibella, was captured on film performing all three tasks with her left paw.
According to polar bear biologists Dr. Stephen Herrero and Dr. Andrew Derocher, this female polar bear’s left-pawedness may be a form of behavioral asymmetry called “laterality.” As a result of being more skilled with their left paws, polar bears may even have evolved to favor the use of their left paw over their right in certain tasks.
In nature, polar bear cubs are born with their eyes and ears closed, which prevents them from seeing or hearing anything. However, polar bear mothers will usually groom their cubs' noses to stimulate the infants and encourage them to open their mouths. In this way, polar bear mothers can then inspect their cubs' teeth by touch as a form of “blindfold.”
To investigate polar bears' paw preference in this “blindfold” method of teeth inspection, Herrero and Derocher compared footage of polar bear cubs opening their mouths for their mothers with footage of adult polar bears lifting their paws up to their own chins. Surprisingly, polar bear biologists found that polar bears presented both of their paws to their mothers just as often, regardless of polar bears' age.
A polar bear’s right or left paw preference may thus become apparent later on in life when polar bears engage in tasks that require more dexterous use of their forepaws. Herrero and Derocher therefore conclude that polar bears are not “left-handed” overall, but instead are laterally inverted–meaning polar bears may be better skilled with their left paws than their right in certain tasks.
This means that polar bears can open doors with both of their paws, but they will probably pick the door handle up with their left paws more often. It also means that polar bears can raise both of their paws up to rest under their chins, but they will probably rest with their left paws more often.