With several species of bird, the male struts around the female giving a vocal display, puffing up his feathers and performing many intricate body movements to gain her attention, while the female appears to display little or no interest.

This ritual is similar to that performed by humans when courtship begins.

Your eyes dilate if you find another person attractive.

It happens automatically, and you can do nothing to stop it.

Albert Scheflen, immediate physiological changes occur when people enter into the same space as a member of the opposite sex.

Watch a person in the company of someone he or she finds at least remotely attractive and see what happens.

In this section we delve into the wild, oft times confusing world of flirtation and courtship behavior.

According to pioneering psychology and non-verbal communications researcher Dr.Bodily muscle tone in the torso, arms, leg, and face tighten up as a person via evolutionary instincts prepares for a possible sexual encounter.The walking gait becomes more limber and bouncy as we endeavor to appear vigorous, healthy, and youthful and convey our suitability as mates, and perhaps replace the ravages of time or too many late nights.Men stand taller, thrust up their chins, expand their chests, and pull in their stomachs making them look like the king of the jungle.Women tilt their heads, flick their hair, and expose their wrists and necks, demonstrating vulnerability and submissiveness.No matter how old, fit, or capable people are, they're all checking each other out.