January 20, 2020 12:01:00 AM
It is not just humans who are left- or right-handed.
Turns out, some squirrels are also strongly lateralised, that is, they actively favour one side of their body over the other.
But unlike humans, where handedness is believed to make brains more efficient, scientists have found that squirrels who demonstrated a paw preference were less good at learning new tasks compared to their ambidextrous counterparts.
Dr Lisa Leaver, programme director of University of Exeter’s animal behaviour course and study author, said: “It has been suggested that being strongly lateralised makes brains more efficient, with each hemisphere focusing on different tasks.
“This could help animals survive, which would explain the evolution of laterality across the animal kingdom.
“In fish and birds, there is evidence that being strongly lateralised is linked to better cognitive performance (brain function).
“However, limited data from studies of mammals suggest a weak or even negative relationship.”
To find out more, researchers from the University of Exeter observed 30 wild grey squirrels who were presented with a perspex tube containing peanuts.
Of them, 12 provided enough data to be included in the research paper, published in the journal Learning and Behaviour.
In order to access the nuts, the squirrels had to learn to use a paw, rather than their mouth as their faces were too big to fit through the holes of the tube.
Dr Leaver said: “We were measuring how long it took them to stop using their faces and to start using their paws to reach into the tube.
“And once they started doing that, we measured which paws they were using – left or right.”
While some squirrels showed ambidexterity by using both their paws to access the nuts, others strongly favour one side.
The team then measured how quickly squirrels learned the task and how strongly they favoured a particular paw, assessing both learning and laterality.
Results showed that squirrels which strongly favoured a particular side did less well on a learning task.
Dr Leaver said: “We found that the squirrels who had stronger tendencies to use either their left or their right paws rather than being ambidextrous were the ones who didn’t perform as well on the tasks.
“So they didn’t learn as quickly, they didn’t earn as thoroughly as the ones who were more ambidextrous.”
She said the findings were in line with these previous mammal studies which suggest “strong lateralisation is linked to poor cognitive performance” but added more research is need to “understand the complex relationship” between the two.