Last week in the comments the discussion sort of evolved to include the topic of chemistry in relationships – and specifically whether chemistry between two people is always reciprocated, or if it's sometimes one-sided. I couldn't find any specific scientific info one way or the other on that, but I did draw some conclusions from other tidbits on “love chemicals” I found. Links to the articles I gleaned this information from are at the bottom of the post, but as always online, take the information with a grain of salt.

That said, here's what I found. There are three basic stages of chemical attraction: lust, infatuation and long-term bonding. Each of these stages is marked by different chemical processes going on in the brain, and while it's controversial, I'd add pheromones to the list somewhere in there (I'm not sure why it's controversial, because the effects on animals are well-documented, but apparently it's more difficult to pin down in humans). Personally, I've used pheromones to “enhance” my own with pretty definitive results, so I happen to think they make a big difference, but it's just personal opinion there.

In any case – romantic chemicals are triggered both psychologically and physically when you're attracted to someone either visually, through pheromones or both. The first chemicals to kick in are hormones, of course – estrogen and testosterone. I'd posit that pheromones play a big role here as well. Hormones are what triggers that first pull of attraction, that feeling of lust toward another person.

Then the big guns come out - dopamine, norepinephrine and serotonin, all controlled by another chemical called phenylethylamine (PEA), a cousin of amphetamine. These are responsible for that twisting stomach/racing heartbeat/can't eat/can't sleep/floating-on-air feeling that we experience when we're “falling in love”. Sadly, we build up a tolerance to these chemicals over time, and the rush fades over a period of six months to three years. Some people crave the chemically induced euphoria experienced in this stage, and jump from one relationship to another searching for that next “high”.

When couples stick together past the infatuation period, yet another set of chemicals take over to form a tight bond over time. Oxytocin is “the cuddling chemical”, and is triggered by both emotional and physical cues. It signals arousal and is released during orgasm, so it's thought that the more sex a couples have, the tighter the bond between them. Morphine-like opiates called endorphins complete the bond, and are steadier and more addictive than PEA. Needless to say, the longer two people are together, the more likely they are to stay together – they get addicted to each other, literally. When people miss a spouse in their absence or grieve the loss of a spouse, it's the loss of those shared endorphins that causes those emotions. Basically, the spouse left behind is going through withdrawal from an addiction (and that's pretty much what it feels like when my husband goes out of town for longer than a few days at a time).

I couldn't find anything to explain how romantic chemistry could be one-sided...but most sites agree that it can and does happen all the time. Personally, I'd guess that it's probably due to a couple of things – one being that one person's pheromones are more “attractive” to a wider range of people than the other (people flock to my husband like flies – me, not so much), and two being that the chemical release isn't just physical, but has a psychological component as well that, for whatever reason doesn't get triggered for that second person. Could be visual, could be something in that person's past...or any number of things, really. That's my personal theory, anyways.

Links:

Science of Love: Cupid's Chemistry

Love Chemistry

What are your thoughts on all of this? Have you ever been “addicted to love”? Are you an infatuation junkie? How do you feel about all of these chemicals and hormones driving our emotions?