CLOSE
iStock
iStock

Scientists Look to Prairie Vole Brains to Understand Monogamy

iStock
iStock

Neuroscientists studying prairie voles have identified circuits in the brain’s reward center that may be a key part of forming social connections. They published their study today in the journal Nature.

Monogamous relationships, or pair bonds, are a lot less common than you’d think, arising in fewer than 5 percent of mammal species, including us and prairie voles (Microtus ochrogaster). What makes us so dang determined to stick with just one other person (or vole)? And what prompts us to latch onto them in the first place?

It’s kind of hard to tell. Human pair bonding is notoriously difficult to study, says co-lead author Elizabeth Amadei of Emory University’s Silvio O. Conte Center for Oxytocin and Social Cognition. “As humans, we know the feelings we get when we view images of our romantic partners,” she said in a statement, "but, until now, we haven't known how the brain's reward system works to lead to those feelings and to the voles' pair bonding."

Scientists love prairie voles. They especially love prairie vole love—or at least the behaviors and brain chemistry that look like love to us. The voles are touchingly tender with one another, grooming, mating, and snuggling their partners until death does them part.

Previous studies have suggested that these intense connections may begin with hormones like oxytocin and dopamine swirling around the brain’s reward system. To learn more, the authors of the current study installed tiny probes in female prairie voles’ brains—the rodent neural version of a wiretap. They then paired the lady voles with males and left the couples alone to get to know each other a little better.

The neural wiretaps told a story of complex interactions between different regions of the female voles’ brains. As the ladies began to bond with their assigned dudes, a flurry of information was exchanged between their prefrontal cortices and nucleus accumbens, areas associated with decision-making and rewards, respectively.

The strength of these circuits varied by vole and seemed to influence her relationship. The stronger a vole’s connections were, the faster she started huddling with her partner. The reverse was also true: The more the two voles bonded, the stronger the neural connections became.

To further test their hypothesis, the researchers plopped lady voles down with new males, but only for a short period of time—not long enough to get attached and mate. During the voles’ brief date, the scientists sent a tiny pulse of light to the brain circuit in question, giving it a little boost. The next day, despite barely knowing the males they met the day prior, the light-pulsed ladies were significantly more likely to choose them over voles they’d never met. Just a little zap had been enough to kick off their courtship.

"It is amazing to think we could influence social bonding by stimulating this brain circuit with a remotely controlled light implanted into the brain," co-lead author Zack Johnson said in a statement.

Some caveats, of course: This study was on prairie voles, who are decidedly not people, and it only included female subjects. We couldn’t tell you what’s going on in those vole boys’ brains.

nextArticle.image_alt|e
iStock
arrow
science
There May Be an Ancient Reason Why Your Dog Eats Poop
iStock
iStock

Dogs aren't known for their picky taste in food, but some pups go beyond the normal trash hunting and start rooting around in poop, whether it be their own or a friend's. Just why dogs exhibit this behavior is a scientific mystery. Only some dogs do it, and researchers aren't quite sure where the impulse comes from. But if your dog is a poop eater, it's nearly impossible to steer them away from their favorite feces.

A new study in the journal Veterinary Medicine and Science, spotted by The Washington Post, presents a new theory for what scientists call "canine conspecific coprophagy," or dogs eating dog poop.

In online surveys about domestic dogs' poop-eating habits completed by thousands of pet owners, the researchers found no link between eating poop and a dog's sex, house training, compulsive behavior, or the style of mothering they received as puppies. However, they did find one common link between the poop eaters. Most tended to eat only poop that was less than two days old. According to their data, 85 percent of poop-eaters only go for the fresh stuff.

That timeline is important because it tracks with the lifespan of parasites. And this led the researchers to the following hypothesis: that eating poop is a holdover behavior from domestic dogs' ancestors, who may have had a decent reason to tuck into their friends' poop.

Since their poop has a high chance of containing intestinal parasites, wolves poop far from their dens. But if a sick wolf doesn't quite make it out of the den in time, they might do their business too close to home. A healthier wolf might eat this poop, but the parasite eggs wouldn't have hatched within the first day or two of the feces being dropped. Thus, the healthy wolf would carry the risk of infection away from the den, depositing the eggs they had consumed away in their own, subsequent bowel movements at an appropriate distance before the eggs had the chance to hatch into larvae and transmit the parasite to the pack.

Domestic dogs may just be enacting this behavior instinctively—only for them, there isn't as much danger of them picking up a parasite at home. However, the theory isn't foolproof. The surveys also found that so-called "greedy eaters" were more likely to eat feces than dogs who aren't quite so intense about food. So yes, it could still be about a poop-loving palate.

But really, it's much more pleasant to think about the behavior as a parasite-protection measure than our best pals foraging for a delicious fecal snack. 

[h/t The Washington Post]

nextArticle.image_alt|e
iStock
arrow
science
The Prehistoric Bacteria That Helped Create Our Cells Billions of Years Ago
iStock
iStock

We owe the existence of our cells—the very building blocks of life—to a chance relationship between bacteria that occurred more than 2 billion years ago. Flash back to Bio 101, and you might remember that humans, plants, and animals have complex eukaryotic cells, with nucleus-bound DNA, instead of single-celled prokaryotic cells. These contain specialized organelles such as the mitochondria—the cell’s powerhouse—and the chloroplast, which converts sunlight into sugar in plants.

Mitochondria and chloroplasts both look and behave a lot like bacteria, and they also share similar genes. This isn’t a coincidence: Scientists believe these specialized cell subunits are descendants of free-living prehistoric bacteria that somehow merged together to form one. Over time, they became part of our basic biological units—and you can learn how by watching PBS Eons’s latest video below.

SECTIONS

arrow
LIVE SMARTER
More from mental floss studios