Let's talk about sex. Or the science of sex, anyway.

Two studies came out this past week, one on condoms and sex toys, and the other on monkeys — and no, it's not some weird, new eroticism that just came out.

I'll keep you posted, though.

According to a Forbes.com report, San Antonio is one of the top places in the U.S. to get your freak on, tying with Portland, Ore., for the No. 2 spot. Denver took the top prize (the Mile-High City, huh?).

Though they didn't do actual man-on-the-street surveys on Americans' sexual practices, the research firm ACNielsen tabulated the amount of over-the-counter contraceptive sales in major cities and from that determined just how lusty their residents were.

The study even suggests that we have Eva Longoria-Parker, among other celebrities, to thank for our emboldened sexual play, citing her brazen endorsement of sex toys (and, may I add, TMI revelations on her sexual encounters with Spurs star and hubby Tony Parker).

Unfortunately, condom maker Trojan found that “single Americans between 18 and 54 use condoms during only one in four of the two billion (billion???? This better refer to a group, or else someone is just being greedy) sex acts they engage in yearly.”

C'mon, single folks. We need to do better than that. But I'm not here to preach — yet. Let's move on to the next study.

The Associated Press reported on research that suggests male macaque monkeys use grooming in exchange for sexual services.

Basically, how many lice does a monkey have to pick to get a good time?

The study found that after a male grooms a female, the likelihood that his hard work would pay off is about three times more.

 On the flip side, the male macaques didn't try so hard if there was an abundance of females. The value of sex was regulated by supply-and-demand factors — the more females, the “cheaper” the males became.

I've never wholeheartedly bought into the whole simian ancestry theory, but this study explains so much.

Whether it's drinks, dinners, favors or simply cold, hard cash, men (and even women) “pay” for sex, intimacy or a relationship in various ways.

Remember the guy who bought you that drink and then annoyingly followed you around the bar or club the rest of the night?

Or that girl who you're just not that into who cooks you a meal or bakes you cookies and seems so eager to please?

If they're anything like their macaque cousins, I hate to break this to you, but — those are investments.

And sooner or later, they'll be expecting a return.