musingsonwomenshealth.com

Reflections on 40 years as a doctor in Women's Health

Ah, on what little things does happiness depend?


Every so often I am jarred awake in the middle of a starry night by the realization that there is more in heaven and earth than is dreamt of in my philosophy (if, indeed, I still have one). Time, I feel, is running out on me and there are far too many things still left undiscovered, unappreciated and, well, yet unacknowledged all around me.

There was a time, of course, when all that we saw was whatever was visible through unaided eyes; before van Leeuwenhoek’s discovery of ‘animalcules’ when he looked through his microscope at water from a pond in the 1670ies no one would have thought of looking for invisible life in a sample of water.

When I was a child and first heard of ‘water bears’ (tardigrades) I was intrigued by the thought of invisible tiny little Teddy Bears swimming around in the water. But when I later saw a rather scary picture of one in a library book and learned that they were largely indestructible, I wasn’t sure quite what to think about them; they weren’t at all as cute as I thought they’d be: no button-eyes, no fuzzy warm fur to cuddle, and too easy for them to hide. I mean, were they waiting for me in the sink as I washed my hands? Or biding their time on my toothbrush? Later I realized that tardigrades (as befits their name: slow walkers), were likely too slow to crawl however sneakily onto children; I assumed that was a result of our running around a lot, and not on our cleanliness. Then, as my age blossomed into maturity, the idea of water bears dissolved into a seldom explored memory stored in a drawer somewhere along with other unseeable things.

Only for ‘germs’ and their other similarly imperceptible friends, did the threat of invisibility remain a worry. Even though I eventually learned there were some friendly members of their microbial family, most of them were an unseen and unheard menace. It seemed as if I had been moving through life in a cloud, while all around me, hostile microscopic beings carried on as if I were a meal ticket they’d stumbled across. And although I later realized that some of them ate quietly at separate tables in another room, I still worried about those that didn’t…

The Covid pandemic heightened my awareness of other unseeable foes in my world as well; toilet seats, and doorknobs were amongst the many things I began to worry about. Anything I might encounter, anything I might accidently touch filled me with an uncomfortable anxiety. Foolish when I think back on those days perhaps, but the pandemic was certainly filled with many  potentially teachable moments as my mother used to warn me if I my hand strayed too close to the forbidden Royal Crown Derby dinner plates she stored in the special living room cabinet.

I grew to realize there might be special proscriptions that applied to anything touchable -or even within digging range in the lawn behind our house. That, and tracking prairie mud through the kitchen, of course.

But now, thanks to an incredibly enlightening article[i] by Karen Lloyd, Professor of earth sciences, and marine and environmental biology at the University of Southern California, I realize there are ecosystems far, far deeper underground than even a prairie child could ever dig; I’m finally beginning to understand the extent of Life’s kingdom.

I think it was initially the eerie picture at the head of the article not to mention its title which grabbed my attention before I could scroll by it. The picture was of a greatly magnified Promethearchaeum syntrophicum (sorry, no idea), which lives very far below the ground, and the author’s name for this and similar deep living organisms: aeonophiles –things that love to live for long periods of time- seemed particularly apt. I was also intrigued by her referring to them as intraterrestrials at a time when the whole world seems preoccupied with extraterrestrial life.

‘Intraterrestrials comprise a vast still-mysterious ecosystem in Earth’s crust containing as many (or more) living microbial cells than are on Earth’s surface… These intraterrestrials never see the light of day, nor do they receive much food input from the surface world. Their world is mostly composed of tiny spaces between sediment grains or miniscule fractures in rocks. Rocks seem solid to us, but to very tiny life, rocks appear porous with lots of places to live.’

Of course, the lack of food or energy to obtain it makes it hard to believe organisms could exist deep underground, ‘although deep geological sources of food and nutrition (often in the form of deep gases and hydrothermal fluids) can support life in some parts of the subsurface, thousands of years or longer might pass with little to no food inputs. This extreme scarcity has extraordinary implications for life. In much of this vast biosphere, there’s not enough energy to drive microbial cell division at anything like a normal rate.’

It would seem that aeonophiles ‘funnel all the meagre power that’s available to them into replacing broken body parts, not dividing into two new daughter cells. So long-term metabolically active dormancy is the only option.’ We know that animals adapt to the daily or yearly rhythms of their environment; ‘an individual that lives for a million years might be evolutionarily predisposed to count on something as slow as island subsidence in the same way that we are evolutionarily predisposed to wait for the Sun to rise tomorrow.’ It would be something like hibernating I suppose, and aeonophiles are waiting for wake-up cues we don’t recognise because our lives are too short to see them.

‘Seasonal cycles are way too fast. The only things slow enough are geological processes. For instance, island subsidence, floods or droughts often occur on 100- to 1,000-year cycles. Submarine landslides, earthquakes, tsunamis and volcanic eruptions might shift materials around on even longer timescales, exposing aeonophiles to new food sources that coax them out of dormancy after hundreds of thousands of years.’

I would have thought that many of these events would destroy any food sources for them, because some marine sediments, including the aeonophiles would get dragged down on the subducting plate and destroyed. But perhaps some seafloor sediments survive these collisions and rather than subducting, they are scraped off and shoved onto a continental plate.

The author also suggests that the characteristics of her aeonophiles upset many of the ways we hope to discover extraterrestrial life: the possibility that, if life on other planets is extremely slow, it might also be almost impossible to detect. 

I mentioned that I sometimes wake at night and stare at the stars through the skylight above my bed; I wonder what’s above me way up there. But now, I also have to wonder what’s below my bed -apart from some lost tardigrades I mean…

[i]https://aeon.co/essays/the-discovery-of-aeonophiles-expands-our-definition-of-life

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