Menstrual synchrony by chance when there is menstrual cycle variability. Yang and Schank argued that when there is cycle variability (i.e., either women have irregular cycles, have cycles of different frequencies, or both), most women will have the opportunity to experience synchrony even though it is a result of cycle variability and not a result of a mechanism such as the exchange of pheromones. For example, consider two women A and B. Suppose A has menstrual cycles that are 28 days long and B has cycles that are 30 days long. Suppose further that when A and B become close friends, B
Menstrual cycle during the fertile phase, many women show a preference for men with darker skin pigmentation. Research on facial symmetry is mixed. Preferences for body features can change during the fertile phase of the cycle. Women seeking a short-term partner demonstrate a preference for taller and muscular males. Women also show preferences of males with masculine bodies at peak fertility. Mixed research has been found regarding body symmetry preferences throughout different phases of the cycle. In short term mates, during the fertile phase, women may show more attraction to dominant men who display social presence. For long-term mates, shifts in desired