why do women have there periods at the same time?

Answer 1

Not all women have synchroinzed cycles. However, women who have synchronized cycles have higher olfactory acuity to 3-androstenol (pheromones), compared with non-synchronized women.

Answer 2

Synchronous menstruation was first described in 1971 by researchers McClintock and Stern. It is a proven occurrence, borne out by additional studies. Though they are still unclear as to exactly why it occurs, the most widely accepted theory is that it is due to pheromones. Others think it's due to some evolutionary carry-over from prehistoric times, when it was common for men to take multiple mates to ensure the survival of the species, but the pheremone theory makes more sense...

Source(s):
McClintock, M. K. (2000). Human pheromones: primers, releasers, signalers or modulators? In K. Wallen and J. Schneider (Eds.), Reproduction in Context: Social and Environmental Influences on Reproductive Physiology and Behavior. MIT Press. Pp. 355-420.

McClintock, M. K. (1998). Whither menstrual synchrony? Annual Review of Sexual Research, 9, 77-95.

Answer 3

When a group of women spend alot of time together, or live together the women who has the more dominant, stronger hormones will shift the cycle of others...It is a proven and documented medical study... The hormones are released through the nose and the alpha femme controls the flow !!!

Answer 4

I learned this from college, We girls put out an invisable odor(chemistry), we can't smell it, but other women bodys pick up on this and bam! There we go. That's why you will notice this if you stay at a capus dorm or say a 2 week camp etc.

Answer 5

Same as most of the people above said.

Answer 6

Why are you asking this?

Answer 7

not all but its bnatural it sok