The fear that girds the lack of platonic touch among American men also fuels the destructive force of their hands, a 2002 study in the journal Adolescence found. Dr. Field was the lead author of the study, which looked at 49 cultures. “The cultures that exhibited minimal physical affection toward their young children had significantly higher rates of adult violence,” she said. But “those cultures that showed significant amounts of physical affection toward their young children had virtually no adult violence.”

A big part of the problem for men is how they handle that 21st-century scourge that kills men younger than it does women: stress. Women employ a tend-and-befriend approach that invites confidence in and cooperation with people who can help them externalize their struggles and find succor.

Not men. When faced with stressors, they tend to turn cowboy, growing stoic, emotionally withdrawn and, too often, isolated. (It’s true that, unlike men, women receive higher levels of oxytocin — the calming, bonding hormone and neurotransmitter — when they are stressed, which enhances their ability to cope. But research shows that men’s, as well as women’s, levels of oxytocin rise when they receive affectionate touch from their partner — and that with doses of oxytocin through the nose, fear is reduced and degrees of trust, generosity and empathy rise.)

If this cowboy approach strengthened men mentally and emotionally, it wouldn’t be a problem. But the weight of having to suppress stress and the resulting emotions that are perceived as unmanly — “gender role stress,” Dr. Zur calls it — doesn’t make men more resilient. It makes them more vulnerable, triggering anxiety and depression, he says. It also prevents them from feeling that they have permission to seek mental health help. A 2000 study by U.C.L.A. researchers finds that “Men are more likely than women to respond to stressful experiences by developing certain stress-related disorders,” such as hypertension, alcohol and drug abuse.

There’s a reason the majority of clients seeking private services from the nascent professional cuddling industry are overwhelmingly male, straight, educated, divorced and in their early 50s. Just as a crushing number of white working-class men are succumbing to opioid addiction and suicide, these men are also suffering emotionally.

They are a population Kory Floyd, a professor of communication at the University of Arizona, had in mind when he wrote about “affection deprivation” in a study of more than 500 participants, published in 2014. Dr. Floyd studied the effects of what he calls “skin hunger,” discovering that people who experience this phenomenon were, among other things, more lonely, depressed, had less social support, experienced more mood and anxiety disorders and an inability to interpret and express emotions. This lack of affection correlated with a “fearful avoidant attachment style,” the same reaction so common in affection-deprived children from orphanages — and in many men. Dr. Floyd said in an email that men are “more likely than women to report that they received less affection from others than they wanted.”

Perhaps it’s not surprising, then, that a 2011 study from the Kinsey Institute at Indiana University, published in the Archives of Sexual Behavior, found that among more than 1,000 heterosexual middle-aged and older married couples in five countries, hugging and kissing were more central to the happiness of men than they were to women.