Menstrual synchrony
Strassmann argued menstrual synchrony defined as menstruation overlap should be quite common. For example, the expected difference by chance between two women with 28-day cycles—which is approximately the average length of menstrual cycles of women at the age —is 7 days. Considering that the mean duration of menses is 5 days and the range is 2 to 7 days, the probability of menstruation overlap by chance should be high.
Bombus morio
Not much is known about the colony cycle of the "Bombus morio." There have been some hints about the length of their cycles, however. The longevity of individual workers within a eusocial bee species is one of the most important indicators of colony growth and reproductive rates of bee colonies. In the "Bombus morio," the average worker bee lives about 41.3 days. Additionally, the egg-to-adult period is about 32 days for workers, 35 days formales, and 32 for queens. These lengths are longer than the average and indicate slow colony growth.