Pax provides an excellent analysis of the evolutionary advantages of human bonding and an intelligent discussion of how our biology -- and specifically oxytocin and vasopressin -- makes the intellectual choice of polyamory not so easy.
Polyamory sounds very utopian because it does away with the concept of jealousy, which has a lot of negative connotations, but the fact is that the same chemicals that produce jealousy produce the bonding effect that we think of as infatuation and love, which most people find pleasant. Most people can't have one without the other, and for most people you can't have sex without some oxytocin production, meaning bonding and jealousy will occur.
He discusses the differences in the level of bonding different people experience, and what that means for relationships. An especially interesting idea is that people should disclose their bondability when they begin relationships, just as they should their HIV status.
Sexual ethics means being up-front with those desires and expectations, in short being aware of the potiential for bonding and not betraying that. It also means being true to yourself. If you're the type of person that bonds easily, don't think you can live a sexually licentious life and not feel anxiety over it. If you're the type of person who just doesn't bond at all, understand that your partners may not be like you, and that you need to let them know before the opportunity for bonding occurs.
There is a bit of misinformation in his post, however. He says that oxytocin takes time to build up in a relationship.
Oxytocin takes time to build up. By having the relationship only last long enough to reach the sexual connection, then terminating it, the bonding formed is minimal.
Speak for yourself, dude! Because estrogen reinforces the effects of oxytocin, women can feel very bonded after a single night of sex.
Moreover, while it's certainly true that repeated interactions and sex can strengthen the bond, in men and women, this bond is not the result of the body's needing to reach a maximum level of endogenous oxytocin for it to take place. Instead, the combination of oxytocin and dopamine in the brain's reward center -- every time -- during orgasm trains the brain to prefer that person.
Still, I think Pax's post is well worth reading for its perceptive and sensitive ideas about how we can negotiate the differences in our neurochemistries.