In another thread, someone posted about the Discovery Channel's "Science of Sex Appeal". I highly suggest people watch it, it has a lot of RP truth (you do have to filter out some hamstering from time to time, but if you can bear it it's quite an interesting watch).

This clip, in no uncertain terms, confirms AF/BB. (Sorry about the quality, I'm not very good at video editing)

@1:50 (Emphasis mine)

So, a woman might choose as a long term mate a partner who possesses good dad traits. [The] kind, um, willing to provide for a woman and her offspring. Then, under certain circumstances engage in unfaithful behavior in order to gain access to those sexy traits, those traits that are indicators of good genes that she could then pass to offspring.

@4:35 (Emphasis still mine)

When they added up how much women moved when dancing and the amount of skin exposed and compared it to the women's questionnaires, they reached a stunning but consistent conclusion. Actually we found quite shocking in our research. Those women, who actually had a long term partner but went out with a friend [and] not with their partner, send the most sexual signals.

@5:17

Women provoke competition by going out on their fertile days, having their fertile partner at home, and sending sexual signals, and then yes, maybe, do some double mating or whatever.

Edit: forgot to link the clip.