University of St Andrews psychologist David Perrett and his colleagues found that people are attracted to folks with hair and eye color like their parents — and the age range they saw at birth.

"We found that women born to 'old' parents (over 30) were less impressed by youth, and more attracted to age cues in male faces than women with 'young' parents (under 30)," the authors wrote. "For men, preferences for female faces were influenced by their mother's age and not their father's age, but only for long-term relationships."

According to a University of Southern California study, when women are ovulating, they prefer the smell of t-shirts worn by men with high levels of testosterone.

This matched with other hormone-based instincts: Women also preferred men with a strong jaw line when they were ovulating.

Body language experts agree that posture speaks louder than words.

Keeping your hands stuffed in your pockets and your shoulders turned inward sends the signal that you're not interested. But talking with your hands and standing in an open stance shows that you're available.

Your voice signals your interest.

Women's voices go down when they're attracted to somebody, and men's go up.

University of Massachussets psychologist Joan Kellerman asked 72 unacquainted undergrads to pair off and stare into each others eyes for two minutes.

"They later reported they had increased feelings of passionate love and affection towards the other person," Scientific American reports. "This suggests that long periods of eye contact can connect you to someone and even ignite feelings of love inside you for that person you have never previously met."

Tall people — especially men — tend to make more money than everybody else.

A 594-person study found that it's the same case for dating. "Taller men do enjoy a noticeable dating advantage," concluded author Virginia Polytechnic Institute and State University psychologist Wayne E. Hensley.

In 1974, Donald Dutton and Arthur Aron wanted to test the connection between sexual attraction and anxiety. They put men into two conditions. They either walked across a high, shaky bridge or a low, sturdy bridge. Afterward, they met a female experimenter who asked a series of questions and gave the men her phone number "just in case."

The men who met the woman after walking on the high bridge were more likely to call her than the men who met her on the low bridge. Psychologists call this phenomenon the "misattribution of arousal." The high bridge created a sense of arousal from the anxiety, but men mistakenly thought it was from the attraction to the woman.

That's why doing exciting things — like going for bike rides, riding a roller coaster — makes for many first dates.

Yale psychologist John Bargh performed an experiment in which participants held warm or cold beverages and had to rate whether someone's personality was warm or cold. Participants who held warm beverages judged the person to have a warm personality, because their minds were already primed to think that way.

If you take someone on a coffee date instead of an ice cream date, they may feel more warmly toward you.

It's not only important to be close to someone emotionally — you should also strive to be close physically. According to an experiment at MIT, the proximity of students' dorm rooms increased how close they felt to one another.

This is because they had more passive interactions, like brief meetings as they passed one another in the hallway, which made them feel more intimate.

It's known as the mere exposure effect, which states that familiarity plays a huge role in attraction.

We've all heard that women are attracted to men with nice cars. But men also appear more attractive if they are photographed in a luxury apartment. In a Cardiff Metropolitan University study, a man was photographed with a casual posture in a "high status" luxury apartment and a "neutral status" standard apartment context.

The men with the luxury apartments were rated significantly higher for attractiveness when presented to the female subjects. Researchers determined that the illusion of status-linked property ownership had a high impact on attraction, and that context can make all the difference.

In a University of Michigan experiment, women read vignettes about men. Whenever the story featured a person who owned a dog, women rated them with higher long-term attractiveness. This is because pet ownership signals nurturance and a tendency toward relationship commitment. It also makes you appear more relaxed, approachable, and happy.

People are more likely to be attracted to someone who didn't find them appealing at first but eventually warmed up to them than someone who always liked them. This was revealed in a 1972 study by Jerome Tognoli and Robert Keisner about the gain-loss theory of attraction.

Participants "accidentally" heard the experimenter describe them in either a positive or negative way. It turned out that participants liked the experimenter far more when they gave them an initially negative rating that later became positive. This shows that people find it more rewarding when they need to win someone over.

In a University of Illinois at Urbana-Champaign study on walking speeds of people on a track, researchers found that males walk at a significantly slower pace to match females' pace when the woman is their romantic interest. Meanwhile, friends who were not attracted to one another did not adjust their walking speeds.

In a 1996 study, each participant was rated on physical attractiveness and then randomly assigned to date another participant. Then, participants were asked to rate their satisfaction with their dates. The participants who were more attractive were harsher in their judgments — even if they were both equally attractive. The better looking someone was, the less satisfied they were likely to be.

But this only applies to the really attractive people. For the rest of us, according to the matching hypothesis, we are more likely to love those who are equally as attractive as us.

In a European study about facial age and attractiveness, researchers wanted to determine whether Botox actually does help women find partners.

The women who went through facial procedures experienced a significant reduction in perceived age, and people rated them as much more attractive and healthy. The more treatments the women received, the more they were considered youthful, healthy, and attractive.

In two experiments, researchers in Switzerland examined the relationship between attractiveness and happiness. They found that people's evaluation of attractiveness was strongly influenced by the intensity of a smile expressed on a face. In fact, a happy facial expression compensated for relative unattractiveness.

Researchers in France found that musical practice is associated with sexual selection. In an experiment, a young man holding either a guitar case or sports bag asked 300 young women on the street for their numbers. When the man held the guitar case, more women were willing to give him their number.

In a Slovakian research study, women who wore the color red were more successful in mating-game scenarios. This can be attributed to sexual signaling, because women use the color red to attract potential mates.

Women are attracted to red on men, too, since like the Huffington Post argues, it signals status.

In an Australian experiment, researchers found that women consider faces with heavy stubble more attractive than heavy beards, light stubble, and clean-shaven faces.

Beyond attractiveness, researchers also found that facial hair affects perceived fertility as well. The more facial hair a man had, the more masculine a woman perceived him to be — especially when she was in the fertile phase of her menstrual cycle. It seems that full beards indicate high parenting ability and healthiness.

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