Squirrels Can Be Left- or Right-handed

By: Patty Rasmussen  | 
This squirrel obviously prefers the use of his right hand. Peter Trimming/Flickr (CC By 2.0)

A study at the University of Exeter in January 2020 found that squirrels that strongly favored a paw – whether right or left – perform less well at learning tasks. Ah ... OK. So. Many. Questions.

The first? How did the researchers discover that squirrels favored a side (known as lateralization) in the first place? Moreover, once they knew which paw the squirrel preferred, how did they know the information was an intelligence or performance indicator? Finally, what does it all mean? Can researchers really draw substantive conclusions between lateralization and learning in squirrels and/or humans? Let's see.


Like humans, other animals often favor one side of their body for certain tasks. For example, if you ask your dog to shake hands, he may always offer his left (or right.) The frequency of his offer varies according to the degree of lateralization in the animal.

Dr. Lisa Leaver is the program director of the Master Science Exeter Animal Behavior program. She says some studies suggest that lateralization makes brains more efficient because each brain hemisphere is focusing on particular tasks.

"This could help animals survive," said Leaver in a news release, "Which would explain the evolution of laterality across the animal kingdom."

She explained that in fish and birds there was evidence that being strongly lateralized meant for better brain function, but that "limited data from studies of mammals suggest a weak or even negative relationship."

Leaver and her colleagues were looking for whether there was a correlation between strong lateralization and poor cognitive performance, and they used the gray squirrels at Exeter's Streatham Campus as their subjects.

In the study, the squirrels had to finagle peanuts out of a transparent tube. Typically, squirrels grab food with their mouths but there was a problem: The tube was too narrow for the squirrel's mouth. It had to use a paw. Researchers watched more than 30 squirrels, collecting enough data from 12 of the subjects for their report. They wanted to see how quickly each squirrel figured out the problem (assessing learning) and whether they favored one paw over the other (determining lateralization).

Their conclusion? They say that strongly lateralized squirrels are not as good at learning (which seems counterintuitive considering the problem the squirrel just had to solve). Interestingly, some research also suggests that ambidextrous people (those who favor neither right nor left hand) may be more creative. Again, squirrels may beg to differ.