Alcohol is often referred to as a social lubricant, but its effects on pair bonding have not been fully explored. But a new experiment performed on prairie voles — a socially monogamous mammal — suggests that alcohol may cause males to be more drawn to strangers, while the opposite holds true for females.
Obviously, humans are not prairie voles, so this study needs to be taken with a serious grain (or two) of salt. We socialize differently, we have different cultural norms, and of course, we have different brains. But what's interesting about prairie voles is that they're socially monogamous — they like to stick with a single partner in the long term. What's more, humans and voles neurologically process social encounters and drug-related states similarly — behaviors that are influenced by shared hormones and neuropeptides (which we'll explore further in just a bit).
During the experiment, in which ethanol was administered in small doses via water, paired voles were observed to behave differently depending on their sex. Males chose to spend time with a stranger rather than their partners over the course of a 3-hour "partner preference" test. Females, on the other hand, wanted more "huddling time" — a behavior that the researchers say is a sign of commitment.
Importantly, the alcohol also changed their neural systems in revealing ways. Alcohol wasn't the most proximate cause of their behavior (e.g. its influence on mating behavior, aggression, or motor abilities). Rather, it may have had something to do with its effect on the voles' stress response.
Jennifer Holland from National Geographic explains:
While initially a surprise, the contrasting changes in the neuropeptides in males and females "could reflect the different ways the animals handle stress," says [researcher Andrey Ryabinin]. The neural systems that the alcohol affected in the voles are the same ones that regulate levels of anxiety in these animals.
The correlation between bonding and stress needs to be studied further, Ryabinin says, but he notes there's a certain logic to it: Males, very generally, deal with anxiety with a fight-or-flight response. While both fighting and fleeing are actions that are likely to disrupt social bonds, fleeing is in a sense what they're doing in leaving their partners. Females, in contrast, more often lean toward actions that "tend and befriend"—not a bad descriptor of their cuddly behavior after drinking.
Yikes, I'm not sure I buy that line of reasoning at all. It's quite a stretch to say that males are "fleeing" their partners on account of an alcohol-induced fight-or-flight response.
Ryabinin is quoted further in the NatGeo article:
In humans, there are so many other factors to consider — for instance, the influence of another drinker or a history of drinking-related economic pressures — that might lead to broken marriages. This means that we can use prairie voles to model not just our alcohol-related behavior but [also] the underlying molecular influences on that behavior. More studies are required, but separating biological effects from purely cultural ones could lead to better treatments for both problem drinking and the resulting interpersonal conflicts.
Or, instead of seeking "better treatments," how about drinking less? Now there's a novel idea for improving relationships.
Yeah — not the greatest study we've ever seen. I'd like to see a similar experiment done on humans. But even then I'm not sure what it would prove given the near intractable complexity of studying such a thing.
Read the entire study at PNAS: "Drinking alcohol has sex-dependent effects on pair bond formation in prairie voles."
Image: Everett Collection/Shutterstock.