Why She Looks at Your Ring Finger

Because it knows and tells all. University of Liverpool researcher John Manning has determined that the size of a man's ring finger is related to how much testosterone he received in the womb. That's true of your penis, as well. The more T, the longer they grow. It's interesting to note that your digital symbol of virility is also the finger on which she slips the golden shackle during the wedding ceremony.


Why You Must Watch Your T-Levels

Women are more predisposed (in brain structure and hormone secretions) to settle down and start a family than you are. But committing to family life is easier for men who have lower testosterone levels. A study of more than 4,000 men found that men with high testosterone levels were 43 percent more likely to get divorced and 38 percent more likely to have extramarital affairs than men with less of the hormone.

Guys with high levels were also 50 percent less likely to marry in the first place. Men with the least testosterone were more likely to get and stay married, maybe because lower testosterone levels make men more cooperative. If you're too cooperative for your own good, build some muscle: It will increase testosterone levels over time. You can even coordinate dating with workouts. A study at Baylor University determined that testosterone levels were highest 48 hours after weight lifting.

Why You Should Marry After 25

Quite simply, a man's brain is incomplete before then. Sure, his sexual organs are all present and accounted for, but his prefrontal cortex (PFC) is still developing. Which is too bad, because that's the part of his brain that's involved in judgment, impulse control, organization, planning, forethought, and learning from mistakes. And it won't be fully developed until he's 25.

Why Beauties Make You Stupid

You act like a goof with the Hooters waitress, leaving a tip that doubles the bar bill. But why? Beautiful women cause a man's limbic system (the amygdala and other brain-stem structures, which are in charge of emotion) to fire up at the same time that his PFC checks out, leaving the judgment area vacant. Las Vegas casinos hire beautiful cocktail waitresses, dress them in low-cut tops and miniskirts, and have them pass out free alcohol — all of which encourages men's self-control to take the day trip to Hoover Dam. No wonder the house has the edge.

How You Can Get the Edge Back

When faced with the dilemma of a bad bet on a beautiful woman, remember that her beauty is fleeting, but a bad decision can last a lifetime. It's a very PFC sentiment, in fact.

Why You Love Porn

Guys aren't shallow; it's just that the visual parts of their brains are strong and tend to twang their emotions. Using sophisticated imaging equipment, researchers at Emory University in Atlanta found that the amygdala, which controls emotions and motivation, is much more activated in men than in women when they view sexual material for 30 minutes, even though both sexes report similar levels of interest.

This may be one of the reasons men are much more captivated by pornography than women: For men, it's not just porn, it's personal. Back in the real world, women hijack men's brains by appealing to their strong visual sense. But women can take in a guy's visuals and think, 'Yeah, but how much does he have in his 401(k)?' To avoid the tyranny of the visual, you need to kick-start your responsible prefrontal cortex by asking yourself, What's my goal in a relationship? That can divert you from those short-term, erotic visions.

How Your Nose Triggers an Erection

There's a direct connection between the olfactory bulb, at the top of your nose, and the septal area, the arousal center of your brain. When cells in your nose are stimulated, they send signals to your libido (and hers) to stand up and pay attention. You know what smells turn you on — the evidence is obvious.

As for her, a study at the University of California at Berkeley found that women become aroused when exposed to a chemical called 4.16-androstadien-3-one (AND). The good news? AND occurs naturally in men's sweat, hair, and skin. Take her someplace cold on your date — the favorite jacket or sweater you'll conveniently have on hand to lend her should be loaded with the stuff.

Discover the surprising link between lust and hunger .

Why You Lose Your Erection in Bed

Maybe little Willie is nervous during his big moment onstage. Performance anxiety is about the fear of being judged or not living up to expectations. The body is programmed to see anxiety as a threat, and the nervous system sets up the fight-or-flight response, sending out chemicals to protect us: Our heart races, muscles tense, and blood is shunted from our hands, feet, and penis to the large muscles of the shoulders and hips so we can fight or run away. That's not such a good strategy in bed, however.

Why You Can Be Addicted to Love

As with obsessive-compulsive disorder, love decreases brain levels of serotonin, the neurotransmitter responsible for mood and flexibility. Low serotonin means you can get stuck on ideas — you become obsessed. Which is just fine, unless she suddenly dumps you. That's when the short supply of serotonin makes you vulnerable to depression. In extreme cases, the serotonin shortage can trigger obsessive behaviors, such as exhibiting extreme jealousy or even stalking.

To get those serotonin levels back up before the police come, try exercising more, eating more carbs, and generally distracting your lonesome thoughts. (Road trip!) All of them will boost your serotonin levels.

Why Touch Strengthens the Bond

Oxytocin is your brain's love juice: the bonding and attachment hormone. When you feel connected, empathic, in love, the oxytocin jets are spurting. Women have naturally higher levels of this chemical: It boosts nonsexual bonding between a mother and newborn, and it's responsible for putting babies to sleep after they nurse.

Though both men and women secrete an extra jolt of oxytocin during orgasm, we men go through a 500 percent surge — which explains our special talent for falling asleep immediately after sex. If she complains that she doesn't feel close enough, ask for her help readjusting your oxytocin levels.

Why Women are the Dumpers

Women have greater access to the more negative right side of the brain, one of the reasons they suffer from depression twice as much as men. The right hemisphere also allows women to see the gestalt, or big picture, of relationships, so they tend to know before men when a relationship is not working out.

Where the Thrill Goes

Dopamine and PEA — your powerful attraction chemicals — are strong stuff. But, as with any high, it can't last. Intense feelings of euphoria and obsession start to wane. You again wonder what's been going on in the NFL or whether you should see your buddies. As you come down off the hard stuff, you may actually go through withdrawal, missing the high of the attraction stage.

How to Get the Love Buzz Back

You have a choice to make. Either you go right out and chase that high (and some comely tail) again, or you settle into the longer-term buzz of a committed relationship. Oxytocin and serotonin are your two best chemical friends for the drive toward your 25th wedding anniversary. They're not as exciting to the brain as the attraction chemicals, but they have longer-lasting effects. So you can trade the dizzying high for a sustainable one.

Of course, if you're really smart, you can inject the hot stuff back into any love relationship. Take her away on a trip, spoil her rotten with La Perla lingerie, send her flowers with a dirty note attached, and the little dopamine chemicals come back out and play. Just like the night you met her.

What Makes Your Eye Wander

Blame vasopressin. This hormone is involved in regulating sexual persistence, assertiveness, dominance, and territorial marking. And men have lots of it, naturally. In male voles (night-loving rodents, which probably describes you perfectly), the levels of vasopressin seem to make the difference between stay-at-home dads and one-night-stand artists. Your hormone levels are probably set at the genetics factory, but the more you give in to vasopressin, the more of it you produce. It's your choice.

Before you act on that attraction, here are 14 things your should think about before you cheat .

Should You Stay or Should You Go?

Only your prefrontal cortex knows for sure. Men who have healthy activity in their PFCs have greater empathy, can focus for longer periods of time, and tend to make better husbands. Men who have overactive PFCs tend to be obsessive, oppositional, and argumentative. This can turn them into major chick repellents.

Likewise, men who have low activity in the PFC tend to be impulsive (more vulnerable to affairs), easily distracted (lousier at listening), easily bored (more "business" trips to Vegas), and constantly scamming for that attraction high (more given to looking for love in all the wrong places). To keep your PFC firing on all cylinders, protect it from injury, which can come from using too much alcohol, nicotine, or caffeine. Better still, exercise your PFC by setting goals and following through on them.

Why the Guys in Bands Get Lucky

In a study in Finland, eight male volunteers underwent brain scans while they were having orgasms. (Must have been a fun study.) Overall bloodflow in the brain decreased during orgasm, but it skyrocketed in the right prefrontal cortex — as it does in creative people (like musicians) when they do their creative thing. Now, exactly why did you give up those guitar lessons?

Why She Moans During an Orgasm

It almost certainly doesn't have anything to do with you. In addition to its duties as an orgasm assistant, the right hemisphere has also been called the "God" area of the brain. When scientists stimulate the right hemisphere, their subjects have more religious or spiritual experiences. So it's not too much of a leap to guess that when she moans "Oh, God" in the throes of sexual ecstasy, she may be connecting pleasure to a deeper spiritual place in her brain. Music and dancing can jumpstart the right hemisphere, which means the nuns at your high school were right to discourage it.

10 things you should know about the female orgasm .

Why Her Orgasms are Like Paxil

Sexual climax has an antidepressant effect. Orgasms cause intense activity in the deep emotional parts of the brain, which then settle down when the sex is over. Antidepressants calm the same part of the brain. This calming effect may be why people who regularly have sex experience less depression.

Why It's Better if She Swallows

Prostaglandins, fatty acids found in semen, are absorbed by the vagina and may have a role in modulating female hormones and moods. I also feel duty-bound to report that women who perform oral sex on their mates are less likely to suffer from preeclampsia, a condition that causes a dangerous spike in women's blood pressure during pregnancy. Plus, sperm carries TGFbeta, a molecule that can boost the activities of her natural killer cells, which attack the rogue cells that give rise to tumors. Don't make her beg. Offer.

Why a Foot Massage is Foreplay

When you rub the arch of her right foot, you affect her about 30 inches higher, and a little to the left. The foot-sensation area of the brain is next door to the clitoral (and penile) region, which may be a big reason that women are so focused on shoes — yours and hers.

Carrie Bradshaw was on again, off again with any number of men, but her Manolos endured. And perhaps now we know why Imelda sought solace in 1,060 pairs of shoes. But even if you're not a Filipino dictator, you can make this work for you.

"There are 36,000 nerve endings in the foot," says Kathleen Miller-Read, a massage therapist and spokeswoman for the American Massage Therapy Association. "By exploring these, you can find sore spots all over the body."

If your girlfriend has her feet crammed in high heels all day, she's bound to have aching toes and a sore back. Use your thumb and forefinger to gently pull, twist, and rub below her toes. For her back, focus on the heel of her foot, moving your knuckles in a circular motion all over the heel. She'll let you know when it's working.

Where Your Kinkiness Come From

Weird sexual fetishes or fantasies are brain symptoms. They fall into the category of impulsive-compulsive disorders: impulsive when you can't control the behavior and compulsive when, even though you may want to, you can't stop.

A person who's prone to voyeurism, exhibitionism, bestiality, transvestism, S&M, or infantilism (deriving sexual pleasure from being treated like a baby) often has too much activity in the emotional parts of the brain, as we see in people who have obsessive-compulsive disorders, and too little activity in the PFC, or judgment center. A study of 26 men with unusual sexual fantasies found that using medications to balance these two areas of the brain gave the men significant relief. But then, so did wearing an adult diaper and being handed a rattle. You can't tell with some people. Some of those fantasies you can fulfill.

How to Control Your Brain

Even though men are programmed to look at beautiful women and populate the earth, the human brain, especially the prefrontal cortex, has evolved to the point where, with proper training, we can be thoughtful, goal-oriented, and focused on our families. You are not a rodent, doomed to follow the pattern of hormone receptors in your brain. Ask yourself: What are my goals for my relationships? Stay focused on loving and protecting the people in your life, and it's mind over what really matters.

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