Menstrual synchrony was first demonstrated in a 1971 paper published in Nature by University of Chicago psychologist Martha McClintock. She had observed during her undergraduate days in an all-female dorm that close friends tended to get their periods at the same time.
The phenom was soon dubbed "the McClintock effect" and is widely held as the first example of pheromones—unconscious chemical signals that influence behavior and physiology—among humans.
Though widely accepted as a fact of female life, many psychologists and anthropologists doubt the existence of such menstrual synchrony. Nearly half of the papers published on the topic find no evidence that close co-habitation draws menstrual cycles closer together.
The reason I bring this up is because me and a guy who works at a trading desk down the hall seem to be in full evacuation synchrony.
Every time, without fail when he's gotta pee, I've gotta pee. When he's on his way to the bathroom, I'm on my way to the bathroom. When I've gotta drop a dime, he's dropping a dime.
He and I don't know each other, never spoken a word to each other and work several hundred yards apart yet still our bodies are somehow synchronized.
Perhaps we have the same exact eating and drinking patterns?
It's really fucking weird and it freaks me out. Meanwhile we pretend like we don't notice that every goddamn time I'm in the bathroom, he's in the bathroom and vice versa.