Recent studies have found large changes in cues and behavior when a woman is at the stage of peak fertility. Lap dancers get much higher tips. The pitch of a woman’s voice rises. Men rate her body odor as more attractive and respond with higher levels of testosterone. At this peak-fertility stage, women are more interested in going to parties and dance clubs, and they dress more attractively (as judged by both men and women). Some women’s attitudes toward their own partners also change, according to research by Dr. Haselton along with a U.C.L.A. colleague, Christina Larson, and Steven Gangestad of the University of New Mexico.