What she said

Megan McCardle punctures the " humans are naturally polyamorous" balloon.

I would only add that not only does this new pseudo-science rely overly much on Bonobo research, that Bonobo research itself is highly dubious stuff.

In any case, stop dreaming, science is not going to back up anyone's playboy fantasies. And this for exactly the reason McCardle identifies:

Besides, as Jesse Bering points out, jealousy ('heartbreak") "throws a monster of a monkey wrench into the evolutionists' otherwise practical polyamory".  If we're evolved to be polyamorous, why do we also seem to be evolved to be extraordinarily possessive?  This seems like an evolutionary maladaptation. 

It's a lot like these people who run around arguing that laws forbidding women from going around topless are discriminatory. Here in Ontario, these laws were  ruled unconstitutional and do you what? You could walk around Ontario all day long and never see a bare-breasted woman. There are some, of course (a very tiny number), just as there are some people who want to be polyamorous but the genetic evidence is overwhelming that most women will cover their breasts in public given the chance and most men and women want only one sexual partner.

This isn't some nasty rule imposed on us by puritans in government or in the church. It's what most people naturally want.