Have any of you ever stopped to wonder why we menstruate? It doesn't make much sense, when you think about it. It is, for one thing, dangerous, as I learned on my first solo wilderness expedition.
I was sleeping in my debris hut on my third day out, after a successful day of digging tubers and setting traps. A sort of snuffling sound woke me, and I was instantly alert, adrenaline coursing through my body. There was nowhere to go---debris huts are like little coffins, and once you've wedged yourself in you can't get yourself out in a hurry---and for this reason I'd carefully disposed of all the food I'd cooked and rubbed my skin with charcoal from the fire to absorb the food smell before going to sleep. But something was on my scent. In the next moment I knew who: a clawed paw knocked a new door into my hut and barely missed my thigh. It was a bear. I scrambled out of the new entrance, shouting, which confused the bear enough that it shambled away after a few more deeply interested sniffs at the leaves of my bedding.
It was a few hours before I could think clearly enough to wonder what had attracted the bear. You guessed it: I had begun menstruating, and the scent of the blood had drawn him to me. Might have been nice if my (male) survival instructor thought to mention this possibility! Though, really, it's a little embarrassing that I didn't think of it on my own.
So why on earth put every human female at an increased risk for predatory attack, every month, during her most fertile years? Doesn't that seem like a bad strategy for the survival of the species? There are a few other mammals who menstruate, though for most it is only a few drops, hardly noticeable. Lots of species simply resorb their ovarian linings every month instead of wasting the precious blood and energy reserves. Why don't we do the same?
There are several theories floating around. One is that the energy cost of keeping some lining in the uterus perpetually (as the resorbers do) is simply too high for such large creatures as we bipeds. Another is that menstruation signals the lack of a pregnancy so that swift action can be taken to remedy this oversight ( impregnate that sucker!). My favorite is the cleansing theory, or the idea that menstrual blood carries away harmful bacteria or disease organisms that might have entered via intercourse. There is a lovely poetry in the thought that this fluid, thought so 'unclean' by so many major traditions, is actually the opposite and might even account for the longer lives of females.
When I first moved to California, I was a young and strongheaded creature. I'd lived in my new home, a permaculture community in Pomona, for about 10 days when I calmly built a moon hut in the corner and stayed there for the duration of my menstruation, writing poetry and bleeding into a special sage-filled hole in the ground. I couldn't understand why anyone would have a problem with this. I mean, there weren't any bears around or anything!
I've grown some, and I no longer make a big production out of my moon time. I treasure it as a signal to retreat, to look within, to step back from all the activity and bustle of life. Perhaps, in the end, this is why we menstruate. Predators are out there! What a great chance for women to stay in the caves, and rest. Built-in rest days for the most put-upon gender. I get it.