“Chemistry” between two people, it turns out, literally matters when it comes to picking a mate. While many factors influence our choices, “we are drawn to certain people not only for cultural reasons, such as socioeconomics, intelligence, and values, but also for biological reasons,” says Helen Fisher, PhD, a cultural anthropologist from Rutgers University and author of a new book, Why Him? Why Her?

According to Fisher, we all have “chemical families” associated with dopamine, serotonin, testosterone, and estrogen. People choose partners with chemicals that complement their own. For example, a person with a high amount of estrogen may be attracted to a high-testosterone type.
Falling and growing in love in love is purely a chemical reaction or what is called better human chemical reaction.

If i were to describe a situation in which someone experienced a flood of dopamine and ocytocin, a drop in serotonin, and spikes in adrenaline and norepinephrine, all those brain chemicals going crazy might make you assume this person was overdosing on some kind of highly addictive drug.

You’d be right. The “drug” is called love and the “overdose” is often referred to as “the early stages of love.” The brain chemicals called neurotransmitters have everything to do with the very physical sensations that we all feel when falling in love.

The links among what our body experiences, our emotions, and our subsequent actions are all so intertwined that it would take someone with a PhD in psychology and behavioral science and an MD in neuroscience to sort it all out. However, we can shed some light on the reasons that the early stages of love can be problematic, and the reasons why the later stages of love can lead to a lifetime of satisfaction and fulfillment!¹

In the beginning:

The early stages of love can be indistinguishable from infatuation – almost entirely because of what is happening with brain chemistry. Here’s what happens when you have met someone, sparks fly, eyes meet, tummy feels funny all the time and you suddenly feel your heart beating in your chest when you managed never to notice it before:
Surge of dopamine. This hormone controls the reward-seeking center of the brain. It is associated with a feeling of euphoria, excitement, and (yes) addiction. Cocaine and love both manifest similarly in the dopamine receptors of the brain. Have you ever felt literally addicted to someone? In those early stages of love (or infatuation) it feels like that because the brain chemistry is that of addiction. Crazy, right?

Rise in oxytocin. Oxytocin is the bonding hormone. Nursing a newborn causes it to surge in new mothers. It also floods your brain during orgasm. Result? Your brain is saying, this is your person! The hormone actually causes you to want to stick with this person. That intense feeling of closeness, trust, and bonding that comes from oxytocin during the early stages of love (and later stages too as we shall see) is hard to resist. Oxytocin can result in adverse behavior too, depending on the person. It can result in envy, jealousy, or suspicion, and in highly emotional and imaginative people can lead to stalking. Yikes.

Drop in serotonin levels. At the beginning of love have you ever felt a little obsessive? You can’t stop thinking about someone? You feel anxious, jittery, and your stomach is always full of butterflies? Well there you go. Lowered amounts of serotonin is also seen in people with obsessive-compulsive disorder. So part of the normal brain chemistry when love is new is to be a little OCD, and that can be a problem… or not.

Rise in adrenaline and norepinephrine. These hormones, classics during flight or fight situations, make your heart race, palms sweat, and mouth dry. So it stands to reason that when you see the object of your desire, in those early stages of love, you feel those very physical feelings. If we were facing down a T-Rex it would not be so pleasant, but when our heart races at the sight of our love object, it feels really good. And then we can’t fall asleep for 4 hours till the adrenaline and norepinephrine levels normalize! (Sleepless nights sound familiar when love is still oh-so new?) Interestingly, norepinephrine is also associated with higher levels of emotional dependency.

Frontal cortex shuts down. Brain scans of besotted lovers actually show that the part of the brain responsible for making good decisions actually stops working. This is a dangerous place to be. When judgment centers are not functioning, people are willing to risk everything for the relationship. Your friends might be waving their arms and trying to get your attention but you don’t get it. What’s the problem?

Amygdala and mid-temporal cortex go off-line. This is interesting as often during fight or flight (as when flooded with adrenaline) the amygdala is the only part of the brain that still works, but when we are in the early stages of love, even this part of the brain bails on us. The amygdala controls fear and the mid-temporal cortex controls negative emotions. So when they are silenced by our addiction to our love object, we are literally incapable of seeing the pitfalls that may be inherent in the situation. We can’t feel afraid of what might go wrong because the parts of our brain that take care of that for us are on strike.

#SYMPTOMS
There are various psychological, physical and emotional symptoms of having good chemistry with another person. It has been described as a "combination of basic psychological arousal combined with a feeling of pleasure". The nervous system gets aroused, causing one to get adrenaline in the form of "rapid heartbeat, shortness of breath, and sensations of excitement that are often similar to sensations associated with danger". Other physical symptoms include "blood pressure go[ing] up a little, the skin...flush[ing], the face and ears...turn[ing] red and...[a] feeling of weakness in the knees". One can feel a sense of obsession over the other person, longing for "the day [when they return] to that person". One can also uncontrollably smile whenever thinking about the other person.