While you may spend hours scouring beauty counters searching for miracle concoctions to help you look more attractive, what others inherently find beautiful about your face may actually be based more on proportions than potions.What are some of these markers of beauty? And more importantly, why do we find them to be beautiful?“All of these questions are linked to evolution,” says Dr. Pamela Pallett, a researcher at Dartmouth University. “You want to have a healthy mate because that person likely has good genetics, and the faces we perceive as beautiful can signify good genetics.”

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Not all model-skinny or angular faces are considered ideal: From an evolutionary standpoint, fuller faces indicate heart health and immunity to infections. So, to some degree, we are programmed to be more attracted to certain faces over others. Sexual dimorphism, a fancy term for sex-specific traits, is one of the major factors in determining what we find beautiful. The more feminine a woman’s features are, the more attractive she’s perceived to be.

“For women, things like large eyes, a small nose and fuller lips are generally found to be more attractive since they are considered to enhance facial femininity,” says Dr. Viren Swami, a Reader in Psychology at the University of Westminster, co-author of “The Psychology of Physical Attraction,” and YouBeauty Attraction Expert. One study zeroes in further and notes that a bigger forehead and smaller-than-average chin and nose are found to be more desirable in a woman.

The reasoning? Researchers believe that we’ve evolved to consider female-specific traits as markers of a high estrogen-to-testosterone ratio. This implies high fertility— in the end, it’s all about making healthy babies.But just because you don’t look like Megan Fox doesn’t mean you’re out of luck. It’s important to note that it’s less about your specific features than it is about the overall face, says Dr. Swami. In other words, as long as your features collectively feminize your face (even if you have a larger nose or thinner lips, for instance), you’re still considered pretty. “If high cheekbones contribute to greater femininity, then the total look would be perceived to be attractive,” he explains. “Not necessarily just the high cheekbones on their own.”

While we’re talking cheeks, you’d be surprised to know that not all model-skinny or angular faces are considered ideal. A St. Andrews University study shows that facial adiposity, or the perception of weight in the face, was actually rated as more attractive to men. From an evolutionary standpoint, fuller faces indicate agreeable cardiovascular health and immunity to other infections. Good health equals healthy babies, right? At least that may have been our ancestors’ (unconscious) reasoning. Symmetry and average-ness are also equally important when it comes to perceptions of beauty (yes, believe it or not, being average is cool). Both appear to indicate high variations in individual proteins, which lead to fewer birth defects in offspring.“

Symmetry works because the idea is that if you have a history of poor developmental stability—for example, a major illness or a nutrition deficiency early on—then you tend to have asymmetrical features,” Dr. Swami explains. So evolutionary psychologists believe humans have “evolved to find healthy facial features attractive, and symmetrical facial features are a good indication of health.”

Another reason you might be found attractive is because you’re familiar. In a study at Brandeis University, there was a higher rate of agreement among close friends, siblings and spouses on what they considered attractive than among strangers, suggesting that attractiveness has a strong social component, too.Interestingly enough, Dr. Swami repeatedly found in his research an idea he refers to as the “love-is-blind bias”: “People who have already formed romantic relationships idealize their partner’s facial features, so they actually perceive them to be more physically attractive than other people would,” he says. But once you break up, the spell is over. You will soon see what others do, a more unbiased version of your ex. Those bushy eyebrows you once found so endearing? Yeah—not so much anymore.

A luminous, unblemished complexion is another factor in attractiveness—so don’t ditch your facialist just yet. There are mainly two reasons for that: Flawless skin indicates good health and youth. Smooth and relatively hairless skin indicates low levels of androgens and high estrogen. Both indicate fertility. What’s more, skin free of acne and other dermatological issues is perceived to mean healthy genes (hence, greater chances of producing healthy—you guessed it—babies).

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So we come to the magical powers of makeup. “Foundation smoothes the skin, making it appear healthier and younger,” says Dr. Pallett. “Eye makeup and lipstick can also accentuate your natural femininity.” The darker and more contrasting your lips are from the surrounding skin, the more attractive. The reason? It’s associated with agreeable respiratory health, better oxygen levels—even sexual arousal. Looks like pin-up models with their bright red lipstick had the right idea.

So if it’s all about evolution, why can’t everyone just agree on who’s beautiful and who’s not? When you talk about individuals, it gets a little more complicated. Evolution explains why we find certain attributes attractive—to a degree. Factors like voice, facial expression, body language and personality also enhance one’s appeal, meaning physical features only take you so far before your inner beauty shines through.