Animal IQ

This Little Rodent Mates for Life. Can It Teach Humans How to Love?

If you want a good relationship role model, look no further than the prairie vole. These adorable creatures don't just mate for life; they also have surprisingly egalitarian relationships, splitting parental duties and nest-building tasks equally. It's easy to understand why they're such a popular test subject for scientists studying social behavior. A 2013 study uncovered a clue as to why these mousy creatures are so faithful: The act of mating actually changes their genes.

Can't Get You Out of My Head

Scientists know that the neurotransmitters oxytocin and vasopressin are big drivers of pair-bonding, both in humans and in voles. They also know that partnered prairie voles have higher levels of those chemicals than voles who have yet to mate. They've even dosed montane voles, another vole species that plays the field more than its prairie brethren, with those neurotransmitters and watched them become hopeless romantics — or become more monogamous, at least.

But they still didn't know one thing. "If mating causes the release of the neuropeptide, how does this kick into a higher gear for the rest of the animal's life?" Thomas Insel, the head of the U.S. National Institute of Mental Health, asked Nature. It's a good question. It's easy enough to see what happens in the brain during the magical rollercoaster of new love, but it's not that easy to figure out why those changes stick around after you've been together for a while. Luckily, Florida State University researchers were on the case.

You Can't Spell LOVE Without VOLE

For a study published in 2013 in the journal Nature, neuroscientist Mohamed Kabbaj and his team gathered voles who had been shacked up together for six hours but hadn't mated. Then, they injected some of the voles' brains with trichostatin A (TSA), a drug that blocks an enzyme that usually prevents gene expression. They specifically targeted the nucleus accumbens, the brain region that's associated with feelings of reward and pleasure. They found that, even though they hadn't mated and had only been together for a few hours, the voles treated with TSA formed pair bonds — and, tellingly, had higher levels of oxytocin and vasopressin receptors. When they compared the brains of TSA-treated voles with the brains of voles who had mated, they found similar patterns. This told the researchers that mating actually changes the expression of genes that code for those neurotransmitters.

What, exactly, does this mean for humans? It suggests that once you're in love, your brain may be forever changed. If what's true of voles is true of humans, epigenetic changes might take that cocktail of chemicals that flooded your brain when you fell in love and keep them going so you stay in love. Your sweetie may have changed your life, but they may have also changed your genes.

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Learn more about the science of love in "The Scientific American Book of Love, Sex and the Brain: The Neuroscience of How, When, Why and Who We Love" by Judith Horstman. We handpick reading recommendations we think you may like. If you choose to make a purchase, Curiosity will get a share of the sale.

Written by Ashley Hamer May 24, 2017

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