The Anatomy Of An Alpha Male

We miss the days when all it took to woo a woman was a winning smile and a couple of witty one-liners. Life was simpler back then, back before scientists started to measure all the secret ways women size men up. Practically every week, a new study comes out that reveals another hidden method females use to pick potential partners from a crowded pack of men. And most of the time, we have no idea we're even being judged. Case in point: According to new research in the journal Nature Communications, women rate guys with high levels of testosterone and stronger immune responses as more attractive.

Bet you didn't know she finds your antibodies sexy, right? And wouldn't it be great to know if you have other features that stealthily turn her on? Good news: You have plenty of them. And we did all the leg work to let you know which of your body parts, gestures, and accessories scientifically stand out most to her. Starting with a dynamite immune system , here's what you need to polish up before you hit the town tonight.

2. Your Five O'Clock Shadow

Kiss clean-shaven goodbye. In a study at Northumbria University, women rated pictures of men with light stubble as the most attractive, and said a man sporting it was the ideal romantic partner. Though women scored full beards highest in masculinity and aggression, fuzzy faces bottomed out as the least attractive. Learn how to grow the perfect stubble here.

3. Your Smooth Baritone

Gentlemen, get your Barry White on. There's a reason the soul master was a total ladies' man—because his legendary low croon made women swoon. And you can do the same: According to a 2011 study in Memory & Cognition, women have a stronger preference for hearing a deep-voiced man talk.

4. Your Favorite Fragrance

Men who use cologne are more confident than those who don't, says a University of Liverpool study. But the same study also found that when women simply see a man apply a scent, they consider him more attractive. Easy as that: Use a scent you like, and your confidence carries you. Use our Scent Selector to find the right cologne for any date.

5. Your Barren Pits
Listen, we're not telling you to go underarm commando, but a new study out of the Czech Republic found that when ladies sniffed odor samples from shaved armpits and armpits with hair grown for 6 to 10 weeks, they liked the smell of hairless dudes better. It's your call, but a couple of snips might not hurt (as long as you're careful).

6. Your Loaded Guns

BREAKING NEWS: Big muscles carry big benefits—especially when it comes to the ladies. Research out of UCLA confirms that yes, women are indeed attracted to muscular guys. (We were shocked, too!) A series of six studies found that fit men are catnip to women looking for fun, and they have twice as many partners as average Joes and weaklings. Just one more reason to hit the gym.

7. Your Red Attire

Inject some rouge into your wardrobe. According to a study in the Journal of Experimental Psychology, women are more attracted to dudes in red than any other color, finding them more attractive, powerful, and sexually desirable. Use a photo with a simple touch of red—a tie or a deep red button up under a blazer—to get her attention. (Discover the clothing she wishes you would wear.)

8. Your Ritzy Ride

Procuring a luxury sports car isn't as easy as, say, buying a red shirt, but nevertheless: If you're looking for a fling, zip around the block in a Boxster. In a 2011 study from the University of Texas at San Antonio, women were more likely to choose Porsche drivers for a date and less likely to choose them for marriage. (Fast car = fast hook-up.)

9. Your Firm Handshake

Strengthen your grip, stat. A good handshake isn't a shortcut to her bed, but a bad one can doom you. Hands are loaded with tactile nerves, and people with weak, clammy handshakes were perceived as shy and neurotic in a University of Alabama study. So hold your drink in your left hand and give her a firm but not bone-crushing grasp. Pay attention to her grip as well: The same study showed that women who give firmer handshakes tend to be more adventurous.

10. Your Average Package

Believe it or not, bigger doesn't always mean better in the penis department. Women rate extremely long penises as less attractive than those of a more average length, according to a 2010 study in the Archives of Sexual Behavior. Unless you're a member of the Red Hot Chili Peppers circa the early '90s—Google it—this tip's for the bedroom only.

11. Your Towering Presence

Sorry, shorties. A study in the Evolutionary Psychology Journal found that tall guys have more attractive partners than vertically challenged men. But if you're stuck below 6 feet, that just means you'll have to do a little extra work: Learn 4 ways to mimic the confidence of tall people and start reaping the benefits you deserve.

12. Your Handy Bouquet

Pink carnations, red roses, yellow daffodils—don't forget the flowers. French researchers recently found that if you want to increase your odds of making a good first impression with a woman, it's as simple as bringing her a bouquet—or, if it's too early in the relationship for that, reserving a table at the nearest garden cafe. So potent is the effect of fresh petals, the study found, that merely sitting near a floral display caused the man to "appear more attractive and sexier." Score!

13. Your Acoustic Axe

Good news, would-be rock stars: Chicks really do dig guys who play guitar. Women love men who sing and play music for them, says Helen Fisher, Ph.D., a biological anthropologist at Rutgers University and author of Why We Love. "Indeed, anthropologists now think this is why humanity developed our advanced ability to sing and compose music: to win at love," she says.