Listeners to a person letting loose with a roar can accurately estimate the size and formidability or the human noise maker. Christopher Intagliata reports.
The animal kingdom is full of species that use sound—growls and bellows and roars—to signal size. Dogs do it. Red deer do it. Koalas do it.
But now we can add humans to that list. Because a new study suggests we can size up other people by the sound of their roar alone.
On supporting science journalism
If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
First, researchers took the circumference of 61 men's and women's biceps, measured their grip strength, and their height. Then they told 'em to let loose a roar.
"I would probably describe it as the most hellish version of Groundhog Day you can think of." Jordan Raine, a behavioral ethologist at the University of Sussex. "If you just imagine 30 actors in training coming into a small room one after another and roaring at you, um, yeah it was an experience, that's for sure."
His team then played those roars back to a separate group of male and female listeners, who'd also been measured for strength and size. They found that men correctly rated other men as substantially stronger than them 90 percent of the time, based on roar alone.
Men did tend to underestimate women's strength by the sound of their roars, and women overestimated men's strength. But, in general, roaring like a wild animal seemed like a pretty accurate way to telegraph body size and strength.
The researchers also found that regular shouting did not seem to have the same effect as a roar. "So what the roaring is actually doing is having this exaggerating effect on strength, which is very similar to the adaptations that non-human mammals possess that allow them to exaggerate their strength as well." The full results—and more roars—are in the journal iScience. [Jordan Raine et al., Human Listeners Can Accurately Judge Strength and Height Relative to Self from Aggressive Roars and Speech]
The finding could have practical, real-world applications too. For example, soldiers have roared in battle throughout history to attempt to intimidate the enemy. "And the U.S. National Park Service actually recommends roaring as a defense strategy against bears."
Just hope that the bears' hearing is better than their eyesight.
—Christopher Intagliata
[The above text is a transcript of this podcast.]
It’s Time to Stand Up for Science
If you enjoyed this article, I’d like to ask for your support. Scientific American has served as an advocate for science and industry for 180 years, and right now may be the most critical moment in that two-century history.
I’ve been a Scientific American subscriber since I was 12 years old, and it helped shape the way I look at the world. SciAm always educates and delights me, and inspires a sense of awe for our vast, beautiful universe. I hope it does that for you, too.
If you subscribe to Scientific American, you help ensure that our coverage is centered on meaningful research and discovery; that we have the resources to report on the decisions that threaten labs across the U.S.; and that we support both budding and working scientists at a time when the value of science itself too often goes unrecognized.
