President Richard Nixon made Father’s Day a federal holiday in 1972, though you can trace the day of recognition back to West Virginia in 1908. Today, reports there are more than 70 million fathers in the United States. Sure, fatherhood conjures images of men hoisting children up on their shoulders, of soccer games and dance recitals, and otherwise unwavering care and support — but what does fatherhood mean, physiologically?

Reduced high-risk behavior

Researchers from Oregon State University (OSU) assessed more than 200 at-risk boys starting at age 12 through age 31, measuring for men’s crime, tobacco, alcohol, and marijuana use over the 19-year study period. When controlling for the aging process, “fatherhood was an independent factor in predicting decreases in crime, alcohol and tobacco use,” said David Kerr, lead study author and assistant professor of psychology at OSU, in a press release.

When men in their 20s and early 30s became fathers, they showed greater decreases in crime and alcohol use in comparison to those who had their first child in their teens or early 20s. Kerr speculated “having children at a more developmentally-expected time could have been more able or willing to embrace fatherhood and shed negative lifestyle choices.”

Lowered testosterone levels (which is a good thing)

A study out of Northwestern University found men are biologically wired to care for their offspring, and when they become a father, their testosterone levels drop (among other hormonal changes). Researchers cited testosterone is what boosts a male’s tendency to compete for a mate, so if levels remained high, so would their “mating-related activities.”

“Fatherhood and the demands of having a newborn baby require many emotional, psychological, and physical adjustments," study author Lee Gettler said in a press release. "Our study indicates that a man's biology can change substantially to help meet those demands." Moreover, Gettler’s research revealed lowered levels of testosterone may also protect men from certain chronic diseases.

Weight gain (which is another good thing)

Slate cited a study published in the journal Biology Letter that found male mammals, like primates, can“gain as much as 20 percent of their body weight,” when their mate is pregnant. The idea is with more weight, males will have more energy to expend when their new baby arrives. These are what researchers also call “sympathetic pregnancy symptoms” — and they don’t just include weight gain.

“Sympathetic pregnancy symptoms in men are referred to as ‘couvade’ (derived from the French ‘to incubate or hatch’), indicating that men share some of their mate's pregnancy symptoms,” they wrote in the study’s discussion. “These symptoms include weight gain, nausea, headache, irritability, restlessness, backache, colds, and nervousness.”

Improved brain

In the same Slate article, authors cite separate research conducted on male mammals that found soon-to-be-fathers experience enhancements in their brain’s prefrontal cortex. This cortex is located in the very front of the brain, and it plays a role in abstract thinking and thought analysis, which also helps regulate behavior.

The study in question saw “after childbirth, the neurons in this region showed greater connectivity, suggesting that having young children could boost the part of the brain responsible for planning and memory, skills parents need when having kids gives them more to keep track of.” Live Science found, too, that childcare behavior can increase dad’s oxytocin levels, otherwise known as the love hormone. It’s no wonder that some scientists believe oxytocin could one day be used to treat brain disorders.

More improved brain changes after the baby is born

James Swain is a psychiatrist at the University of Michigan, and his research studies the brain’s response to a baby’s cries. He told NBC News when a baby cries, the “brain activity patterns don’t change as quickly for fathers as they do mothers,” which he jokes is why fathers are so quick to roll over three weeks post-birth.

But, Swain found after four months, the father’s patterns were more like the mother’s; they catch up, neurologically. He also found this effect is stronger for stay-at-home dads, which then suggests this proximity to children (recognizing and responding to the baby’s cries) fosters a stronger father-baby bond.

"Fathers seem to be particularly important in modern developed Western nations like the U.S., because there are so many people who are living in isolated nuclear families, largely separated from their extended family,” Swain said. “That limits the number of potential helpers out there. ... It's really important that fathers step up."