This is Scientific American 60-Second Science, I'm Ashley Pap.

Monogamy and animals, and let's be honest, and humans, too, is a funny thing.

Only a few animal species have been lumped into the one partner for life category.

And even then, there are exceptions to those rules.

Scary voles are furry little rodents that live throughout North America.

They're a particularly interesting species because they form lifelong partnerships.

On a Lee Speary, a behavioral neuroscientist with Smith College in Massachusetts

and the University of California at Berkeley studies vol monogamy in the wild and in the lab.

So I would define monogamy as a formation of a lasting partnership

or a social relationship between mates.

Social relationships are very important for human biology,

and periables are one of the only species that are studied in the lab that exhibit this trait.

Monogamy is fairly rare in rodents, and it's also unusual for rodents to form lasting social relationships of any kind.

We already know about some things that support monogamy in the wild,

like when mates are scarce and it makes sense to hold onto the one you're with,

or when both sexes stick around to raise their young.

But so far, there isn't one clear explanation as to why or how animals opt for only one partner.

Whatever the reasons, staying monogamous requires effort from both sides.

To better understand how lifelong bonding works,

Beere and her team wanted to know if both male and female periables make equal investments and making the long haul work.

To find out, the researchers set up an experiment with three phases.

In the first phase, they had to teach the periables how to open a door controlled by a lever.

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