Biochemistry is in the Air, Literally - Spring is Coming

Well folks, it's that time of year again.  You know, when society convinces you that the only way to show your affection for that "special someone" is by buying them gifts of chocolates and flowers.  Don't forget to make your dinner reservation AT LEAST two weeks in advance...oh wait.

Alright, enough of that nonsense.  What we REALLY care about is the science, not that love-y dove-y junk. As much as I disdain Valentine's Day (with all due respect, St. Valentine), one of the most fascinating topics to me is the biochemistry of love.

What causes us to be attracted to someone?  Molecules, what else?!  You may recall a post by Chris some time back about the affection we develop for our pets, caused by the molecule oxytocin.  Don't worry, there's much more where this comes from!

Most of us are more or less familiar with the term "pheromone".  To catch everyone up to speed, here's a quick crash course:

As mentioned in the clip, pheromones are molecules in the air that we can pick-up on, closely associated to attraction.  

A recent and very interesting correlation made between pheromones and attraction involves MHC genes. Now, think of the term "genes" as a reference to a code.  This code contains all of the information that keeps us alive.  Amazing, isn't it?!  MHC genes, in particular, code for strong immunity responses that assist in fighting off disease.  Selection favors a diverse combination of MHC genes for this reason.  To put it another way, think of MHC genes as a set of super powers for fighting off evil - the larger the variation of super powers, the better.  

Low and behold, how attracted one is to another is directly correlated to how different the other's MHC genes are to one's self!  In other words, we are naturally attracted to those who are genetically more different than ourselves.  This makes sense since selection favors genetic diversity.  It reminds me of the movie Eternal Sunshine of the Spotless Mind.  The two main characters of the movie, Joel and Clementine, could not be more polar from each other, really putting the phrase "opposites attract" into scientific context:

Just when you thought smell was the leading factor, there's also taste [1]!  Believe it or not, you can "taste" the genetic compatibility of your partner of interest during certain...activities.  Still unconvinced and feeling lonely?  Fear not, there's a new dating site for all the skeptics that will match you up based on genetic compatibility!

So here's to love, in the spirit of...biochemistry!

1. Wyatt, Tristram D. Pheromones and animal behaviour: communication by smell and taste. Cambridge University Press, 2003.

Questions?  Comments?  Confusions?