You may not need a ‘love hormone’ to make a lasting connection
/The hormone oxytocin is considered the original “Love potion number nine” of The Searchers fame.
Produced in the hypothalamus and released into the bloodstream by the pituitary gland, scientists have long believed oxytocin is the central player in behaviors including pair bonding, parenting, and lactation – all necessary for reproduction of the species. The hormone can be released through touch, music, and exercise.
But a study in the journal “Neuron” suggests that it may not be the single most important hormone for love. Researchers discovered that animals without the ability to respond to oxytocin find other ways to produce behaviors that are important to their survival.
The research is important because just 5% or less of the world’s 4,000 mammal species are estimated to practice any form of monogamy. Humans are one of those species, which may explain our emphasis on things like Valentine’s Day, big weddings, and anniversaries.
It turns out that prairie voles are another species that pair bonds, essentially mating for life.
To better understand the connection between pair bonding and hormones, investigators studied prairie voles that had been genetically modified to ignore signals from the “love hormone” oxytocin. Researchers found that pair bonding occurs even without oxytocin.
"We were shocked because that was really, really not what we expected,” said Devanand Manoli, an author of the paper and a psychiatrist at the University of California, San Francisco, in an interview with National Public Radio.
"One of the behaviors that's really the most adorable is this huddling behavior," he told NPR. "They'll sometimes groom. Sometimes they'll just fall asleep because it's very calming. And that's very specific to the pair-bonded partner."
Experimenters set out to disrupt pair-bonding and other oxytocin-related behaviors, such as parenting, milk production, forming social attachments, and socially monogamous pair bonding. Earlier studies showed these behaviors vanish when scientists use drugs to block oxytocin in adult prairie voles.
This time the team removed fertilized eggs from female prairie voles, edited the genes, and then placed the embryos in females that were hormonally ready for pregnancy.
Researchers concluded that the voles found other ways to perform behaviors needed for their survival.
Sue Carter, a professor of psychology at the University of Virginia and distinguished university scientist at Indiana University, Bloomington, told NPR that she suspects the prairie voles’ behavior can be explained by biological need that is common with voles and humans.
"We can live without fine clothing. We can live without too much physical protection. But we cannot live without love," Carter said.
She speculates that the need for pair bonding in voles – like the need for positive relationships in humans – may be strong enough that it trumps the alluring power of oxytocin.