That would appear to be the takeaway—from my reading—of this new study:

People whose brains registered a stronger response to sexual cues were likely to have more sexual partners than those whose brains showed a reduced response, a researcher at UCLA’s Semel Institute for Neuroscience and Human Behavior said today. “These are the first data we know of that link brain responses to actual sexual risk behaviors,” said Nicole Prause, who directs UCLA’s Sexual Psychophysiology and Affective Neuroscience Laboratory.

Breaking in for a second: I'm the first to tell people that more sex partners = more risk. But risks can be mitigated for, if not eliminated, and it's possible to be, to borrow a phrase, not just an ethical slut but a risk-aware, risk-mitigating slut as well. The study's authors seem to be conflating "more sex partners" with "general sexual recklessness." But someone can have fewer sex partners and be sexually reckless—fuck rarely but impulsively (while drunk or high), not use protection, not use common sense, etc.

Back to the study:

The 40 men and 22 women—ranging in age from 18 to 40—participating in the study were asked how many sexual partners they had in the past year. They also were shown 225 images that included non-sexual images and those that ranged from mildly sexual to explicitly sexual. Researchers used an electroencephalogram, or EEG, to gauge electrical activity in the brains of study participants. The scientists focused on a specific activity in the brain called late positive potential, which reacts to images based on emotional intensity. “The researchers found that participants who reported having had a higher number of sexual partners in the previous year exhibited similar late positive potential responses to both the graphic and less-graphic sexual images,” according to a UCLA statement....

Said Prause: “If your brain responds very strongly even to very tame pictures of sex, then you seem to be easily sexually excited in the real world, too." She said that “if we show very explicit sex pictures, eventually everyone’s brain responds strongly. It is those weaker images, just hinting at sex, that show the difference.”

So... they found that the kind of horny people who have more sex with more people are easier to crank up, i.e. their imaginations go to dirty sexy places more quickly than the imaginations of people who have less sex and fewer sex partners.

This we already knew, right?