Of the dozens of hormones in the human body, oxytocin is probably the most overrated. Associated with romance, orgasms, euphoria, and other pleasures, this chemical has long been billed as the “hug hormone,” the “morale molecule,” even the “source of love and prosperity.” It inspired popular books and TED talks. Scientists and writers have asserted that blowing a person’s nostrils promotes compassion and generosity; Online sellers market snake oil oxytocin concoctions as “liquid confidence.”

But like my colleague Ed Yong and Others they have It has been written repeatedlymost things He talked about hormones it is, At best, hyperbole. Smell the chemical It doesn’t. make people more cooperative or trustworthy in a safe environment; Attempts as a treatment for children with autism spectrum disorders have yielded inconclusive results. Despite decades of great research, it has been shown that the versatile molecule can sometimes create all kinds of hot and cold treats. Species– Cooperation in Marketsmonogamy in prairie voles, parental care in Marmosets And sheep– Root other ConditionsOxytocin can transform organisms from rats to humans. Violent, Scaryeven Prejudice.

Now researchers are finding that oxytocin may not only be insufficient to form a strong bond, it may even be unnecessary. A A new genetic study Prairie rockers—soft, fist-sized mice that have been pups for long periods of time thanks to the touch effect of oxytocin—can mate permanently without it. The revelations could shake the foundations of the entire subfield of neuroscience, and prompt scientists to reconsider some ancient evidence that once held oxytocin to be the be-all and end-all of animal love. Cuddles probably occur without the classic cuddle hormone—even in the most classic-looking organisms.

Oxytocin is not necessarily obsolete. “This shouldn’t be taken as ‘Oh, oxytocin doesn’t do anything,'” says Lindsay Saylor, a neuroscientist at Cornell University. But researchers have good reason to be a little nervous. For all the chaotic, inconsistent, and even shadowy data collected in human hormone research, data from prairie voles has always been considered a rock. Native to the Midwestern United States, they are famous for being small rodents. One of the few mammals Those who are monogamous for life and raise their children together. For many decades and in different geographies, researchers have documented how mice nestle and comfort themselves when they are stressed. In anger Resist Developments of other voles that try domestic failure. And every time they did, “it was oxytocin sitting at the center of the story over and over again,” says behavioral neurobiologist Sue Carter. He pioneered some of the first studies on the prairie-vole bond.. The molecular pathways driving the behavior also seemed clear: When stimulated by social behavior, such as flirting or sex, a region of the brain called the hypothalamus released oxytocin. The hormone then latched onto her receptor, causing many love-pigeon effects.

years of follow up Studies He continued to carry that thought. When scientists give prairie voles drugs It prevents oxytocin from binding to the receptor, the mice began teasing their partners after any trial. Meanwhile, stimulating oxytocin receptors was enough to encourage them to settle down with strangers. The link between oxytocin and pair bonding was so strong, so repeatable, and so unquestionable that it became canon. Zoe Donaldson, a neuroscientist at the University of Colorado at Boulder, remembers once getting a proposal rejected because, according to the reviewer, “We already know everything there is to know about prairie voles and oxytocin.” “

So when Stanford neurogeneticist and psychiatrist Nirao Shah and his colleagues set out to isolate oxytocin receptors in prairie voles a decade ago, using a genetic technique called CRISPR, they thought their experiment would be cruel. Part of the goal, Shah told me, was proof-of-principle: Researchers haven’t yet perfected the genetic tools for voles the way they have with more common lab animals like mice. If the team’s manipulations are successful, Shah envisions, they will produce a strain of mice free of oxytocin’s effects, making them unfaithful to their mates and indifferent to their young—proving that the CRISPR machine has done its job.

That was not what happened. Rats continued walking with their families, pretending nothing had changed. The findings were puzzling. At first, the team thought the experiment had simply failed. “I remember sitting there, Wait a second; How is there no difference?” Christine Berenzen, a neurobiologist and psychiatrist at UC San Francisco who led the study, told me. But when three different groups of researchers repeated the manipulations, the same thing happened again. It sounds like you have successfully lifted off the car’s gas and still see the engine screeching to life after drinking gas. Something went wrong with the tests. Larry Young, a neuroscientist at Emory University who wasn’t involved in the new study, says that’s unlikely: Young’s team, he told me, got nearly identical results in his lab.

Explanations for how decades of oxytocin research could have progressed are still shrouded in mystery. It is possible that oxytocin binds to more than one hormone receptor—something that has been studied Over the years it has hintedCarter told me. But some researchers, among them a young one, suspect a more radical possibility. Perhaps, without the normal receptor, oxytocin no longer does anything – forcing the brain to create an alternative route to love. “I think other things make up for it,” Young said.

That idea is not a complete rejection of the old research. Other prairie vole experiments that use drugs to suppress oxytocin receptors have been done on hormone-stimulated adult animals, said Devanand Manoli, a UCSF psychiatrist and neuroscientist who helped lead the new study. Wired to respond to oxytocin during development, those rat brains were unable to compensate for the sudden loss late in life. But the Stanford-UCSF team created animals without oxytocin receptors Since birthIt could have triggered the entry of another molecule that could bind to another receptor. Maybe the car never needed gas to drive. He removed the tank from the ride and replaced it with an electric.

It would be easy to see this study as another blow to the oxytocin propaganda machine. But the researchers I spoke with think the results are more telling than that. “This shows us how important pair bonding is,” Carter told me—to the prairie voles, but also to us. For social mammals, companionship is not just emotional. It’s a critical part of how we build communities, survive the childhood past, and ensure future generations can do the same. “These are some of the most important connections any mammal can make,” said Bianca Jones Marlin, a neuroscientist at Columbia University. When oxytocin is present, it’s probably providing the oomph behind that closeness. And if not? “There is no single point of failure for the evolution of something,” Manoli told me. Knocking oxytocin off the pavement can feel like a letdown. But it’s comforting to consider that the journey to bonding isn’t that unbreakable.

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