Isn’t it gratifying (if you’re a man) to witness the rehabilitation of good old aggressive behavior? All of these years we’ve heard so much about testosterone-poisoning, how the evils of the world can all be traced back to the male propensity for in-your-face behavior.

THEN, of course, women discovered that to survive in the male-dominated workplace they had to memorize a page from the masculinity handbook and many became more aggressive than men. Now comes the greatest endorsement for fundamentally forward behavior: It’s good for your health.

In a recent study, researchers from the University of Nebraska and Pennsylvania State University found that moderately aggressive men had higher levels of T lymphocytes and B lymphocytes, immune cells commonly called “helpers” and “suppressors,” than more reserved fellows. Both lymphocytes are involved in controlling immune response.

Loose translation: Real men don’t need flu shots.

The study, reported in Psychosomatic Medicine, was based on an analysis of 4,415 men between the ages of 30 and 48. To determine how aggressive they were, the researchers first asked the men a range of questions, from how often they skipped school when they were younger to whether they had ever fought with weapons. They then measured the men’s immune response by taking blood samples.

The researchers could find no association between higher testosterone levels and immunity, but that’s hardly surprising: Testosterone is a notoriously elusive target. In men it fluctuates on hourly, daily and seasonal bases. It spikes and dips depending on whether you feel like a winner or loser and climbs in response to just thinking about a hot date on Saturday night.

Many studies have documented a linkage between testosterone and aggressive behavior that now seems indisputable, and it seems well within the realm of scientific probability that the hormone can be credited with being involved in this latest good news, researchers say.

Yes, credited. Isn’t it nice to think of testosterone in this new, positive way?

STRONG CHIN, STRONG BODY?

The findings fit nicely with what’s known about the immune system and dominance — or at least the look of dominance. An analysis of the class of 1950 at West Point showed that the most reliable predictor of a soldier’s future rank was a formidable appearance — a muscular face, strong chin and brow, and good skeletal structure — “a gestalt kind of thing,” according to Allan Mazur, who did the study. Though the cadets’ resemblance to Stone Cold Steve Austin provided few clues as to how they’d do in mid-career, they accurately predicted who would eventually become generals.

The powerful look also predicted another Promethean quality: The generals, on average, fathered one more child than their pudgy-cheeked, weak-chinned classmates.

What does this have to do with immunity? In favoring Dick Tracy types, as they have long done, women are unconsciously choosing genetic resilience. The heavy lower face typical of the dominant male specimen is a visible record of the surge of androgens that helps morph a skinny lad with a weak chin into a meaty general.

EVOLUTIONARY INSIGHTS

Researchers theorize that the link between aggression and immunity dates to man’s early days, when guys who were best at finding food and protecting their kin were the most aggressive in the clan. In response to the injuries and infections that accompanied these high-risk behaviors, a healthy immune system evolved.

But not, as it turns out, as healthy as women’s. In the paper in Psychosomatic Medicine, Dr. Douglas Granger, who teaches biobehavioral health at Penn State, noted that in general women have stronger immune systems than men.

In studying that page from the masculinity handbook, they’ve apparently really done their homework.