The etiology (cause) of PMS or premenstrual dysphoric disorder is still unknown and I about lose my marbles when I hear people stating that PMS is 100%, for sure, due to the fall of progesterone. No! One thing we do know is that is not simply a progesterone issue (maybe allopregnenolone in the brain…maybe).

“Studies show that women diagnosed with a premenstrual disorder do not have higher levels of estrogen or progesterone than the general population.”
-Hofmeister et al. 2016

But, if it isn’t hormonal, why does PMS affect up to 80% of the female population?

As a scientist when I hear such percentages I immediately think, “What if PMS isn’t a mistake, what if this cluster of behaviors and symptoms was evolutionarily advantageous.”

And I am not alone in this hypothesis.

First principles.

What is going on in the back half of the luteal cycle?

You are either maintaining a pregnancy OR you’re not.

AKA as a pair you were able to fertilize and implant an egg or you weren’t. And, what are the main psychological symptoms of PMS?

-Depressed Mood
-Anxiety
-Irritability
-Decreased interest in usual activities

AKA this whole sex “thing” we have had over the follicular phase didn’t work, time to break up the band.

“Even if small proportions of women in infertile relationships took up new, fertile partners as a result of PMS, this would be sufficient to select and maintain PMS in populations.”

The average Paleolithic female was estimated to have about 100 menstrual cycles throughout her lifetime, whereas the new-age female is likely to have closer to 400. Remember the point of your existence on this planet is to turn calories into babies and in modern societies we are intentionally horrible at this. Talk about an evolutionary mismatch.

“Inclusion of severe premenstrual symptoms as a full category in the DSM-V may encourage more research on PMDD and PMS. However, it does continue to stigmatize PMS and PMDD as being disease states. Under the hypothesis we have proposed, PMS and PMDD are not diseases or ‘syndromes’, but arise as a normal consequence of adaptive strategies developed during our evolutionary history, similar to morning sickness and other apparently maladaptive states… It is important that the search for such proximate causes of PMS symptoms does not overshadow the ultimate cause, which may be to maximize reproductive fitness.”
-Gillings 2014