Some flirting comes from our basic evolutionary make-up. This is especially true of preening. A man will puff himself up to look bigger just like many male species in the animal kingdom. He does this by arching his spine or leaning back in a chair with his hands behind his head and resting an ankle on his knee. He may also stretch and inhale deeply to expand his chest. Some have even referred to these actions as "peacocking." It is an instinctual behavior meant to make a man appear desirable and in his prime.

If a man receives a positive response from you when he makes eye contact, he may try to get closer. Depending on his level of boldness, he may head straight for you or somehow work his way close enough to maybe strike up conversation. If you are receptive, he may lean in as you chat. Small touches could follow. Brushing a piece of lint from your sleeve could be used as an excuse to make contact. Wiping away a crumb from your mouth is another, more intimate, example of his desire to connect.

When a man is interested, it will show in his body language. His posture will be "open" meaning no crossed arms or tightly crossed legs. His body will likely be angled directly at you. If he is looking at you but his body is turned away, it probably means he's not as engaged as you might like him to be. Mirroring is another good indicator. He will begin to unconsciously reflect your body language, by standing or sitting in the same position you are or making similar hand gestures as yours.

Once you are engaged in conversation, he may flirt by asking you questions about yourself and telling you a personal tidbit about himself in return. The Social Issues Research Centre calls this "reciprocal disclosure." His interest in your answers will show in his attentiveness. Eye contact and head nodding are a couple of way to know he is actively engaged. He may use inviting gestures like extending his hand out, palm up, as though offering you something. Joking and teasing with you are also indicators of alert participation.