What a woman wears on any given day is the result of a quick calculation involving many variables: Is it raining? Does she have a date after work? Is her underwear label showing? But, more powerfully, it's the result of millions of years of evolution

That's where you come in. Evolution is all about sexual selection-and for women, at least, choosing a mate begins with choosing how we display ourselves. As you may suspect, when we're dressed our sexiest, we're dressing for other women, in a way. No, it is not a threesome fantasy-it's a competition. For you men, that is.

Once you've learned the secret language of a woman's clothing, you'll be a better judge of when she's signalling sexual interest. And that's helpful whether you're in a relationship, or looking for one. Here's what to watch for.

I'M WEARING Something red when everyone else is in black
I'm thinking I feel confident-and I want to be noticed.
"We have an intuitive sense of colour," says Dr Minnu Bhonsle, a psychologist at Heart To Heart Counselling Centre, Mumbai. Red, a hot colour, suggests that a person is outgoing, whereas blue, a cool colour, suggests that she's reserved. So people who wear red are trying to attract more attention to themselves than people who wear blues or greys.

Heck yeah, I sometimes feel like showing off, so I'll wear something to attract your attention. But since the colour of my clothing may also have a lot to do with fashion trends (purple is the new black-no, wait, pink is), you can't always tell a lot about a woman based on her chosen hue alone. Instead, take notice: How am I dressed compared with other women in the room? That's your clue.

Your move: This is really easy. Say, "You're the best-looking woman in the place." It's a can't-fail, evolution-based compliment that's guaranteed not to land you in the dog house. "Women are very aware of what other women are wearing," says Kristina Durante, a PhD candidate at the University of Texas at Austin. "We don't want to wear the same thing as someone else. Often the first thing we do when we walk into a room is determine where we stand in attractiveness compared with the other women around us."

I'M WEARING  High heels
I'm thinking Is he looking at my butt?
If you're noticing my body more than my shoes, they're working. Heels raise the buttocks so they become visually attractive to men, says Gad Saad, PhD, author of The Evolutionary Bases of Consumption.

But you already knew that, at least instinctively. This boost of the butt produces a curve of the lower back toward the abdomen which, in mammals, is the position of female sexual receptivity, Saad explains. It's no coincidence that strippers still wear stilettos after they've shed their clothing. Real-world evidence: I don't recall ever wearing a pair of flats on a first date.

Your move: Say, "Hot shoes" (after a few dates, it's acceptable to say "Your butt looks hot in those jeans"), and then take me somewhere fancy. "If she's wearing heels, she's not saying, 'I want to go to a mela, a guys' watering hole or to watch a cricket match at your place'," says Dr Bhonsle. "She's saying, 'I'm looking for sophistication, not down-home comfort.'" She's also saying, "I don't want to walk a kilometre to the next bar. Kindly hail us a taxi or be nice (and smart) enough to drive your car."

I'M WEARING A belted dress or skirt
I'm thinking I feel pretty, classically feminine and flirty.
Nothing makes me feel more ladylike than a dress, especially the belted variety, which slims the waistline, enhances curviness, and is currently in style. (Perhaps you noticed the big-belt trend if your girl dragged you to Fashion.) There is an evolutionary explanation for waist-cinching (corsets in the 19th century, wraparound dresses in the 1970s): Small waists appeal to men.

Dr Rohit Jaiman, consultant psychiatrist, Fortis, New Delhi, says curviness, reflected in a woman's waist-to-hip ratio (WHR), is somewhat dependent on her oestrogen levels. It can show "fecundity, or basically her overall fertility," he says. Some research shows that a WHR of about 0.7 (picture Mallika Sherawat or Lara Dutta... okay, you can stop now) is what is most universally appealing to the male gaze.

"Males enjoy looking at these types of bodies because mating with females with such body types is more likely to produce viable offspring than it would with those who don't," says Dr Jaiman.

David M Buss, PhD, author of The Evolution of Desire: Strategies of Human Mating, says that "belts and even colours and patterns can draw a man's attention to a woman's WHR, as well as give the appearance of a more pronounced WHR." A navel piercing may be her way of calling attention to her flat tummy, he says.

Your move: Be a gentleman. When I'm dressed up in a dress, I feel different, a more mature kind of sexy than when I'm wearing, say, hot jeans or short shorts. Accordingly, I want to be wooed by a more mature man. Old-school gestures are welcome: Wrap an arm around my waist, hold a door open. You'll charm my pants off. Oh, right, I'm not wearing pants. How convenient. (Yes, we have this thought, too.)

I'M WEARING  High heels
I'm thinking Is he looking at my butt?
If you're noticing my body more than my shoes, they're working. Heels raise the buttocks so they become visually attractive to men, says Gad Saad, PhD, author of The Evolutionary Bases of Consumption.

But you already knew that, at least instinctively. This boost of the butt produces a curve of the lower back toward the abdomen which, in mammals, is the position of female sexual receptivity, Saad explains. It's no coincidence that strippers still wear stilettos after they've shed their clothing. Real-world evidence: I don't recall ever wearing a pair of flats on a first date.

Your move: Say, "Hot shoes" (after a few dates, it's acceptable to say "Your butt looks hot in those jeans"), and then take me somewhere fancy. "If she's wearing heels, she's not saying, 'I want to go to a mela, a guys' watering hole or to watch a cricket match at your place'," says Dr Bhonsle. "She's saying, 'I'm looking for sophistication, not down-home comfort.'" She's also saying, "I don't want to walk a kilometre to the next bar. Kindly hail us a taxi or be nice (and smart) enough to drive your car."

I'M WEARING A belted dress or skirt
I'm thinking I feel pretty, classically feminine and flirty.
Nothing makes me feel more ladylike than a dress, especially the belted variety, which slims the waistline, enhances curviness, and is currently in style. (Perhaps you noticed the big-belt trend if your girl dragged you to Fashion.) There is an evolutionary explanation for waist-cinching (corsets in the 19th century, wraparound dresses in the 1970s): Small waists appeal to men.

Dr Rohit Jaiman, consultant psychiatrist, Fortis, New Delhi, says curviness, reflected in a woman's waist-to-hip ratio (WHR), is somewhat dependent on her oestrogen levels. It can show "fecundity, or basically her overall fertility," he says. Some research shows that a WHR of about 0.7 (picture Mallika Sherawat or Lara Dutta... okay, you can stop now) is what is most universally appealing to the male gaze.

"Males enjoy looking at these types of bodies because mating with females with such body types is more likely to produce viable offspring than it would with those who don't," says Dr Jaiman.

David M Buss, PhD, author of The Evolution of Desire: Strategies of Human Mating, says that "belts and even colours and patterns can draw a man's attention to a woman's WHR, as well as give the appearance of a more pronounced WHR." A navel piercing may be her way of calling attention to her flat tummy, he says.

Your move: Be a gentleman. When I'm dressed up in a dress, I feel different, a more mature kind of sexy than when I'm wearing, say, hot jeans or short shorts. Accordingly, I want to be wooed by a more mature man. Old-school gestures are welcome: Wrap an arm around my waist, hold a door open. You'll charm my pants off. Oh, right, I'm not wearing pants. How convenient. (Yes, we have this thought, too.)