Girls want to date them. Boys want to be like them. And there’s a reason why bad boys — specifically tattooed ones — capture our attention. Beyond broadcasting the fact that tattoos clue us into a bad boy not afraid of sticking needles full of ink into their epidermis, tattoos are a way to scream male virility and health to the outside world, according to a forthcoming study in Personality and Individual Differences.

The study — “Tattooed Men: Healthy Bad Boys and Good-Looking Competitors” — highlights how little we understand about evolution’s role in attraction. Here’s the basic reasoning: Getting a tattoo, by definition, is painful; sticking a needle chock full ‘o ink is also, you know, a health hazard. And it’s (mostly) permanent. If you emerge from a tattoo unscathed, you just survived a wound. Which means, by definition, that you, dear sir, are a man who is of above-average health and “immunocompetence.”

The researchers — Andrzej Galbarczyk of Jagiellonian University and Anna Ziomkiewicz from the Polish Academy of Sciences — tested this theory IRL by showing 2584 men and women photos of nine actual, non-smiling, torso-and-up, tattoo-less men. The kicker? They were shown in their natural, non-inked state and a Photoshopped state, replete with tats. These photos were then presented to test subjects, who rated the pictures.

Regardless of gender and sexual orientation, tattooed men stood out as more masculine, more dominant, and more aggressive than their non-tattooed versions — in other words, the stereotypical vision of the machismo man.

Okay, so tattooed men were deemed healthy. But what about that key factor of evolutionary biology, that whole mating and attractiveness part? Women, in particular, saw tattooed men and rated them as healthier than their original version — though not necessarily more attractive than the originals. Men, however, saw a tatted up dude and found them way hotter than their plain selves.

Here’s the twist, though: Women don’t buy tattooed men as better partners or potential daddies. They see tattoos as maybe hot, maybe not, and definitely not worthy of more than a one-night stand. Men, however, found tattooed men to be perfectly fine — health- and look-wise — and definitely capable of being partner/father material. This seems to have a stronger effect the more ink a guy adds on: Increasing tattoos turned a woman off but had men positive the guy was future husband/pops material.

Which brings us to two takeaways. First, in a society with an increasing amount of humans inking up and increasingly liberal attitudes about accepting tattoos in the workplace, we’re not quite in a (evolutionary) stage to accept them as signs of an attractive, supportive partner. The tattoos might actually serve as an indicator of crime and violence; given classical societal connections of tattoos with drug lords and gangs, that’s not surprising and probably feeds into the idea that tattoos are permanent and painful in the first place, so a person has to be a bit of a deviant to want them. Second, tattoos should be considered with respect to sexual orientation. While straight females might find them a turn-off, homosexual males won’t — and that plays into what the authors call “male-male competition.”

These effects go beyond tattooing — think piercings, or other signs of “asymmetry.” In other words, anything that shows body abnormalities or modification clue an outsider into how capable a man is of being a father and partner.

In short: If you’re gay, roll up that shirt sleeve and showcase your inked sleeve. If you’re straight, maybe don’t do that — unless you’re looking for a no strings attached one-night stand.

Photos via Getty Images / Kevin Winter