No, a Rat Study Can’t Tell Us About Human Bromance

Photo: Jason Todd/Getty Images

Science of Us has noted, on multiple[1] occasions[2], that university press offices often publish inaccurate or overhyped press releases to try to gin up interest for new research findings, and that media outlets then pick up on these releases in an uncritical manner, exacerbating public misunderstanding about science. And now we have brotally depressing — but telling — example on our hands.

I use that stupid pun because the stories in question are about, well, bros. Take the Washington Post’s headline: “Study: ‘Bromances’ may help buffer males against stress.”[3] Or the Huffington Post’s: “Scientific Evidence Proves Bromances Are Good for Mens’ [sic] Health.”[4] Or Uproxx’s: “A New Study Says Having a Bromance Could Save Your Life.”[5] Makes you wanna group-text your bros and hit the bars tonight with them, right?

Except the study itself, published in Neuropsychopharmacology[6], really doesn’t support these claims, partly because it wasn’t even a study of humans — it was a study of rats. And one that isn’t necessarily easily translatable to humans, either. For the study, a team led by Dr. Elizabeth Kirby of the University of California, Berkeley, took a bunch of male rats who were living in cages with another male rat and immobilized them for three hours. While immobilized, some were in an odor-free environment, some got a whiff of the pleasant smell of peppermint (considered a “neutral” aroma by the experimenters), and a third got the terrifying-to-a-rat odor of fox urine.

The researchers then compared the rats’ social behavior based on the smell they’d been exposed to (and also decapitated them — sorry! that’s rat research for you — so as to test various aspects of their brain and blood biology). To make a long story short, rats who got no smell of peppermint spent more time huddling together and less time fighting, and they shared resources better. Those that got the fox urine were less friendly and cooperative — the idea being that the severe stress of that event freaked them out more than the “moderate” stress of being restrained for three hours. Overall, the stress of being immobilized seemed to make the rats more prosocial and cooperative — and affectionate, in human terms — but when the fox-urine smell was thrown in, the effect was either nullified or partly nullified, depending on what was being measured.

You got all that? The researchers note that to their knowledge, there hadn’t been previous research on “how stressor context (a moderate vs. a more innately threatening stressor) differentially impacts social support behaviors or social dynamics among males.” So this is new, interesting research.

What it isn’t is research on humans. I don’t want to overstate this — there are obviously some similarities between humans and rodents, which is part of the reason medical research on mice and rats is so important. And the researchers do hypothesize that their findings could tie into the fact that humans with PTSD often experience exacerbated symptoms as a result of social withdrawal. But even in this study, the most “traumatized” rats did exhibit more huddling than those in the control group — they didn’t “withdraw” from a source of social comfort the way humans with PTSD might (though they also didn’t huddle as much as those in the control group) — so right away that’s an important difference that complicates the comparison. And, more broadly, it’s just tough to directly compare rats and humans on big, complicated issues like stress and trauma and social interaction. You need to be really careful drawing these sorts of cross-species comparisons.

So I’d be tempted to say that I have no idea how journalists would get the idea that a single study on rats can tell us anything about human bromances. Except I do know where they got the idea — UC-Berkeley’s own press release: “Bromances may be good for men’s health.”[7] If you have a sense of déjà vu, that’s because many media outlets more or less copied this headline.

Now, to be fair, one of the researchers, the graduate student Sandra Muroy, is quoted in the press release as making the human-bromance comparison. But look at the full thing in context:

“A bromance can be a good thing,” said lead author Elizabeth Kirby, who started work on the study while a doctoral student at UC Berkeley and continued it after assuming a postdoctoral fellowship at Stanford. “Males are getting a bad rap when you look at animal models of social interactions, because they are assumed to be instinctively aggressive. But even rats can have a good cuddle – essentially a male-male bromance – to help recover from a bad day.” “Having friends is not un-masculine,” she added. “These rats are using their rat friendships to recover from what would otherwise be a negative experience. If rats can do it, men can do it too. And they definitely are, they just don’t get as much credit in the research for that.”

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