The Subtle Signals of Sexuality

Women put more care and attention into self-ornamentation. They wear more jewelry, make-up, and show more skin. People judge photos of the faces of ovulating women to be sexier (compared to photos of the same women two weeks earlier).
-Haselton (2006) , Durante, Li, Haselton (2008)

Facial skin is relatively unblemished, smooth, and hairless due to high estrogen.
-Samson (2009)

At ovulation, women make more eye contact with male strangers. They look not to learn but to signal interest. Signs include direct eye contact, outstaring, fixing the gaze on the target male then breathing synchronously.
-Grammer (1989)

Female marmosets stare at males and then flick their tongues. This pairing of signals is an invitation for the male to mount.
-Barnett (2006)

One of the effects of estradiol (an estrogen) oozing from the ovary during the most fertile days of the cycle is to boost motivation to mate with men. Another effect is to thin the cervical fluid to help the semen move quickly.
-Evolution and Human Sexual Behavior, Gray & Garcia, (2013)

Girl with a Pearl Earring by Vermeer

On the left is Vermeer’s painting. And on the right, a version I repainted. Now for a little game: guess where these women are in the monthly cycle. Based on the direct eye contact and the slightly parted full wet lips, Vermeer’s is near ovulation. In my portrait, her closed mouth, lowered gaze, missing earring, and high neckline suggest a different time of the month. At midcycle, women make more eye contact with strange males, wear more jewelry, and show more skin. As Vermeer expert Arthur Wheelock points out, the girl is painted as if idealized—she isn’t someone specific. I’d add that the idealization is one of a man seeing a woman at peak fertility and peak receptivity.