Culture and menstruation the ideal of synchronised tidal, lunar, menstrual and seasonal periodicities whose overall harmony (it is believed) confers spiritual power and fertility. To many, such cultural associations appear persuasive in view of the fact that in humans, the menstrual cycle quite closely approximates the moon's 29.5-day synodic cycle, unlike in chimpanzees (~36 days) or bonobos (~40 days). Statistical information from hunter gatherers is lacking, but where large-scale western studies focus on women's peak reproductive years—removing outlier values—the cycle length gravitates around 29.1–29.5 days, while the figure for women in their thirties shortens toward 28 days. In no extant human population has
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