Are you looking for a new lover or mate? Use your animal instincts and heightened powers of observation to get what you want—sex.

For the past 500 million years, every member of the animal kingdom has used specific signals to communicate their interest in mating. (Charles Darwin called these signs "submissive displays" because they make the subject seem more approachable.) As both social and sexual creatures, human beings have also developed a nonverbal system to express our sexual intentions. We may or may not be conscious of it but we definitely use and notice it when around a potential mate; it is called “body language.”

Body language is defined as nonverbal communication by use of bodily signs such as facial expressions, posture, and gestures. However, sometimes signals are misinterpreted for several reasons. For example, studies have shown men are more likely than women to misconstrue friendliness as sexual interest. In order for you to avoid potential embarrassment and wasting time on someone who is not interested, it is beneficial to have at least a basic understanding of body language.

Seeing any one or a combination of the following signals may signify physical attraction:

Eyes—Your eyes are an important flirting tool. Prolonged eye contact between two people indicates intense emotion, and is either an act of love or an act of aggression. It means either a person likes you or you’d better watch out! It is so powerful that in normal social encounters we avoid eye contacts of more than one second. In a flirting situation, when you gaze at someone for more than a second and they return the look, they are most likely interested.

Dilated pupils—In general, pupil size and blink rate increases when people view something that interests them. When lovers look into each others’ eyes, they subconsciously are looking for pupil-dilation signals and each becomes excited by the dilation of the other’s pupils. Romantic encounters are most successful in dimly lit places so everyone’s pupils dilate, creating the impression people are attracted to each other. You can also try to increase the blink rate of the person you are talking to by blinking more yourself, and the other person will unconsciously blink more to keep up with you, resulting in you both being more attracted to each other!

Eyebrow flash of recognition—This cue seen as a universal coded as a sign of friendliness or openness. You make eye contact, smile and lift both eyebrows. It is seen as a positive signal that says “I’m happy to see you.”

A facial expression to avoid is called the “tongue show.” In tongue-showing, the tongue protrudes slightly and just the tip shows between the lips. The tongue show has been decoded as a socially negative “don’t bother me” sign in gorillas and human beings.

Shoulder positioning—One of the most easily observed signs of attraction is lifted shoulders. This motion indicates that a person has activated what biologists call the "cute response" that reveals a softer, more submissive side. This is an emotional, involuntary muscular response to someone you like, and it has a universally appealing effect. In a possible dating situation, this unconscious movement tells you that the person you're interested in wants to get to know you better.

Palm revealer—As you interact with your potential love interest, watch his or her hands. In particular, observe whether the palms are facing upward, while gesturing or resting on a table. The brain is programmed to recognize vulnerability and friendliness in this motion. Women tend to find men’s hands and wrists attractive, and can be flaunted with rolled-up sleeves. In contrast, palm-down gestures are seen as aggressive, such as slapping a desk for emphasis.

Pigeon toes—Pigeon toes may not sound like the sexiest of displays, but an inward rotation of the feet suggests explicit interest. Anatomically referred to as "tibial torsion," this toes-turned-in posture occurs when someone feels simultaneously attracted and intimidated by you. By "shrinking" the body, the person is creating a less intimidating profile. In contrast to pigeon toes is the more aggressive military posture. This toes-out, hands-behind-the-back posture is suggestive of soldiers at ease, and its indifference is a sign that it’s best to keep your distance.

Physical proximity—When we like someone, we tend to move and lean closer to get more attention. The distance you have from the person you are flirting with is important to observe, because it affects the quality of the interaction and reflects how the person you are interested in really feels about you.

Posture—Besides words and facial expression (which can be covered with a fake smile), our posture can reveal our true mood and feelings. This is known as “nonverbal leakage” because while we're busy controlling our words and facial expressions, our true feelings “leak out” in our posture. If just his or her head is turned towards you, with the rest of the body leaning toward another direction, this is a sign that you do not have your conversation partner's full attention. Positive signs of attentiveness and interest would be a subject’s body oriented towards you, particularly if he or she is also leaning forward.     

Gestures and touching—A single nod or nodding of the head while you are speaking usually means he or she is interested and wants to hear more of what you are saying. Likewise, a subject using a lot of gestures while speaking shows interest. Light touching or caressing, not grabbing, can convey positive emotions.

Mirroring—This concept is simple: do what they do. If they take a sip of their drink, for example, then a few moments later you do the same. The idea behind this is that we tend to be attracted to people who like the same things we do.

Legs crossed—A person that has his or her legs crossed is sending a signal that they are closing themselves off to you. In contrast, a legs-opened position is seen as welcoming and inviting.

Some cues used by women are licking of their lips, hair twirling, tossing or flipping, fondling a cylindrical object (a hint of things to come later), dangling her shoe at the end of her toes.

Some cues used by men are the Dale Head Drop, named after the guy who invented this little move to get women rushing to his side. You meet a woman’s eyes, then knowingly drop your head to the side, as if to say, “Hey, you know you want me. Come over here and get me!” Also, putting your thumbs in your belt, with your hands at your hips’ side is interpreted as a sign of being confident in your sexuality and size.

Also keep in mind nonverbal messages, being less under conscious control, can betray discrepancies between the spoken words and true feelings of a person. Research shows that nonverbal signals carry five times as much influence as the verbal conduit and when the two are conflicting, people, especially women, rely on the nonverbal message and ignore the verbal expression. One error to avoid when observing body language is interpreting a single gesture without considering other gestures or circumstances.

Not only watch the cues others are sending, but be sure to be aware of the signals you are sending. Each smile, frown or raised eyebrow sends a signal releasing hormones such as oxytocin (the cuddle hormone) to adrenaline pumping through you, producing a range of emotional states. It's been shown that changing your own body language can not only change how others feel about you but can also change the way you feel about yourself.

When you see someone you are interested in getting to know intimately, remember to approach with open body language and keep both your eyes and ears open to find out how they really feel about you. Good luck and go get laid.