Love has always been a topic that has fascinated me. Since I was a little girl spending my days watching Disney movies, I always dreamed of finding my prince charming who would sweep me off my feet, and we would live happily ever after. When I reached adulthood, I started to get mad at those movies that taught me that love was a fairytale. More than just depressing romantic comedies taught me that often, love does not work out: my friends, family members, and my own love life showed me that it's often a painful process. It goes against all rational thought, and though it can be wonderful, I wonder why it exists at all, and what's actually happening to my body and my brain during this process.

Scientists have often asked the same questions. A study in 2004 investigated hormonal changes when falling in love found that cortisol levels were higher for subjects in love, a state known as "hypercortisolemia." Cortisol is a steroid hormone known to be released in response to stress, and the authors of the paper, Marazziti and Canale, think that increased cortisol is a result of the stress and arousal associated with early phases of a relationship. This may be essential, though, because a moderate level of stress has been shown to promote social attachment among humans and other animals. The study subjects also showed that, when cortisol levels were tested 12-18 months later, they were consistent with normal levels of single people. At this point, the subjects no longer reported being "obsessed" with each other, and therefore probably no longer falling in love. It seems then, that falling in love is a temporary, stressful condition. Once the relationship has passed a certain point, partners may be in love, but no longer "falling."

Marazziti and Canale also make the point that to fall in love presents an evolutionary advantage for our offspring. Several other animal species, especially mammals, also "pair-bond," but why? Several biologists have suggested that it is not only for reproductive purposes, but also to create a "safe and stable environment" in which they can grow up and learn the skills to live on their own. Human babies require an incredible amount of care, or parental investment, in order for them to survive, let alone succeed. The lives of our children is wildly different from, say, squid babies. In the process of mating (see link for more details), a squid essentially hands a packet of sperm to a female, which can generate up to 70,000 eggs for some species. The female then sticks little sacs of fertilized eggs all over the place to try to hide them from predators, and then leave them alone, and go off to live their own lives (though sometimes they don't live much longer after reproducing). From then on, the baby squid is on their own to find food and avoid predators. Not so with human babies, who are essentially useless for their first several years of their lives, and depend completely upon parental care. So it makes sense that they need a stable environment of two parents in love to have a greater chance for survival.