As a general rule, simple questions, especially simple questions with purportedly obvious answers, are the most interesting questions.

While I attended a wedding this weekend, I noticed all of the sex partners seated together, you know . . . husbands and wives and boyfriends and girlfriends (and a few gay couples).

Why do sex partners sit together at public rituals, I wondered.   The obvious answer is that it’s because most sex partners live together, right?  Other people thus see sex partners as couples and feel that they should be invited to important rituals together, especially to important rites of passage, such as weddings.  But why do so many sex partners live together (and hence get invited to prominent social events as couplets)?  After all, instead of living with her sex partner, maybe a woman would rather live with (and then potentially be invited to go to weddings with) a non-sex partner friend or neighbor, or perhaps even her non-sex-partner plumber or accountant.  Or maybe she’d rather attend public gatherings by herself, so that she could freely mingle.  The norm, however, is obvious to anyone who bothers to scan the crowd at a wedding:  the great majority of people who attend such gatherings attend them as sexually-paired couples.

Someone who followed the SSSM model might say that this behavior (of attending prominent rituals with your spouse) is simply learned, or that it is “social convention” or that it “feels right.”   There is a compelling story that can be told about paternity …