When it comes to love (or lust, as the case may be), men and women know what they like when they see it. Ask people to describe their ideal romantic partners, and they might draw a blank or merely offer a vague outline, but that doesn't matter so much, since they'll immediately know when they encounter him or her. According to Rutgers University anthropologist Helen Fisher, the human body is such a finely tuned attraction-seeking machine, it takes only one second to intuitively decide whether someone's physically hot or not [source: Fisher]. Upon closer inspection, we might change our minds, or we just might have found what we've been looking for all along.
To help ensure that the good ones don't get away, our bodies produce a host of physical signs of attraction that grab our attention and direct it toward the dreamboat in question. When those physiological mechanisms kick in, even a brief glimpse of a crush can leave us short of breath and dazed. And unpleasant as some of these reactions might be, we can at least take heart that at some point, the following five lovesick symptoms happen to all of us.