As the bills for roses, chocolates, jewelry and a fancy dinner start to add up this Valentine’s Day you’ll probably grow thankful you’ve only got to impress one person.

That’s one reason you may choose monogamy. But it turns out there’s actually a physiological purpose for monogamy -or pair-bonding- and it’s not just found in humans. UC Davis Professor of Psychology Karen Bales studies physiology and neurobiology in monogamous species and joins us to explain why we choose that “one” special person.  

RELATED: Why Prairie Voles Fall In Love