Every other Friday on NHPR's Morning Edition, the Outside/In team answers a question from a listener about the natural world.
This week, Bill from Lyme, New Hampshire asked: "Do cats and other animals favor one side over the other as humans do? If so, why? And, within a species are there both right-sided and left-sided animals? Is there an inherent advantage to being right pawed or left pawed, or what we might term am-PAW-dextrous? "
Outside/In's new producer Marina Henke and Nate Hegyi looked into it.
Transcript
This has been edited for length and clarity.
Marina Henke: This question had actually never occurred to me. But Nate, what about you?
Nate Hegyi: Um no, this seems like one of those ones where you’re just, like, bored on a Sunday sitting on a chair looking at your dog or your cat and saying “Oh weird. Are they favoring one foot or the other?”
Marina Henke: Totally. So first off, individual animals can definitely show a preference to one side or another. We’ve got walruses that use their right flippers to turn, tree frogs that jump mostly to the left.
Nate Hegyi: Weird.
Marina Henke: Now, you may know that most humans are right-handed… but it can be hard to figure out if an entire species prefers one side or the other. I asked Dr. Stephanie Poindexter, a biological anthropologist at the University at Buffalo, why this might be.
Stephanie Poindexter: There's going to be differences based on the tasks, there's going to be differences based on the environment, whether it's a captive study, whether it's a wild study.
Marina Henke: And you can even see this in humans! Like, there’s a cultural aspect to handedness. Even though 90% of us are right handed we should remember that teachers used to force students to hold pencils with their right hand. For animals, trying to figure out this cultural element is virtually impossible.
Marina Henke: And a good way to think about this is we can’t, like, ask a walrus if they felt social pressure to use their right flipper.
Nate Hegyi: (Laughs) "Were you being bullied, walrus?"
Marina Henke: The last part of Bill’s question is: what’s the advantage of being left or right handed at all? And that comes down to efficiency.
Nate Hegyi: Huh!
Marina Henke: So, when we pick up a pencil to write something down with our one hand, that task is being directed through the opposite side of the brain. It’s called lateralization.
Nate Hegyi: Okay…
Marina Henke: And that leaves the other side of the brain free to, say, think about what groceries you need at the store, or compose a love letter. By splitting up tasks, we’re better able to do two things at once.
Marina Henke: Imagine with me Nate, we are at the customer service desk at Target. And instead of having one big line for everybody who needs help…
Stephanie Poindexter: If you imagine there's a line for returns and there's a line for pickups. X person is doing this task, Y person is doing another task and they know they’re doing that task.
Nate Hegyi: Okay, so like in this metaphor, left brain is doing "pickups," right brain is doing "returns."
Marina Henke: Right. And handedness, we think, is a side effect of specializing with these different sides.
Marina Henke: One last thing Stephanie told me is it is totally possible to notice whether our own animals favor a certain paw. Which I thought was crazy!
Nate Hegyi: (Laughs)
If you’d like to submit a question to the Outside/In team, you can record it as a voice memo on your smartphone and send it to outsidein@nhpr.org. You can also leave a message on our hotline, 1-844-GO-OTTER.
