[kadonoishi]

I'd really like to know if menstrual synchronization is real, because there's a straightforward explanation: temporal herding. In the ancestral environment, it drew predators, so under the normal dynamics of prey and predators it pays to herd together. Herding in space is easy to see; herding in time, as of oak trees tending to produce acorns in the same year, is also easy to note after awhile. So if our ancestors evolved to all menstruate at the same time as a defense against predation, it seems perfectly straightforward. But all I hear is anecdotes that are promptly attacked, so, is this a real physical phenomenon?