In 1992, a pair of anthropologists set out to survey 166 of the world’s societies about their particular experience with romantic love. They found that 147 expressed very similar feelings of associated with love (the remaining 19 were not counted because of discrepancies in the questioning, not because there was any negative feedback).

Love is a universal human experience—and one for which the scientific community has found many psychological and physiological explanations.

The Psychology of Love and Crushes

The potent chemical cocktail that you feel when under the influence of romantic love is dominated by dopamine and is associated with certain areas of the brain, including the striatum, also known as the brain’s “pleasure center.” Dopamine release is causes some of the most wonderful feelings of the human experience, like enjoyment, contentment and satisfaction.

Romantic love also activates areas in the brain, primarily the insula, associated with motivation to acquire a reward, gives value to certain pleasurable, life-sustaining human activities. Essentially, the theory is that our brain creates this sense of euphoria (i.e. love) in order to ensure the continuation of our species.

But what about the earliest form of romantic love—the inevasible and indescribable crush. “Crushes,” as we think of them, are often associated with teenagers—and for good reason. The sweaty palms, racing heart and flushed cheeks are symptoms much associated with awkward cafeteria encounters and passed notes in study hall.

Romantic crushes often occur in the early teenage years, and they are an important (though sometimes insufferable) experience to go through. By this time, young people are leaving their childhood years and entering adolescence. They want to act more grown up, and puberty has sent them into a sexual maturity that differentiates them into acting in more manly or womanly ways.

Psychologically speaking, crushes occur when a person of any age projects their ideas and values onto another person whom they believe possesses certain attributes and with whom they want to be associated. Then, the person with the crush attaches strong positive feelings to this magical image that they have created. It is a powerful mixture of idealization and infatuation. The brain chemicals associated with crushes can wreak havoc (or pure bliss, depending on your point of view) on a person for up to two years.

If a powerful crush lasts longer than two years, it may actually be what psychologists call limerence. This condition can be defined as “an involuntary interpersonal state that involves an acute longing for emotional reciprocation; obsessive-compulsive thoughts, feelings and behaviors; and emotional dependence on another person.” Symptoms include uncontrollable thoughts, extreme nervousness and trouble breathing. If you experience any of these symptoms for a prolonged period of time, you should consult a doctor.

But for most of us, crushes don’t evolve into something that needs medical attention, so you don’t need to worry too much. Crushes are a very normal, healthy part of human experience. The next time you fall for someone and think, “I can’t get them out of my head!” you have brain chemistry to thank for that!