Kills All Known Germs

Cleanliness is not next to Godliness

It is Several Doors Away

We are shown a man washing his hands at the kitchen sink. 'Go to the bathroom', admonishes his wife; 'the kitchen is for preparing food'. This scene appears in a Hollywood film; unsurprisingly so as Americans are decidedly germophobic - I've even seen someone leave a public lavatory by pushing on the door's self-closing mechanism, operating it in reverse. Do not touch this door handle! Use disposable covers on toilet seats! Unzip trousers using disposable gloves! Raise toilet seat with elbow! Sterilise all surfaces with flame thrower! Nowadays we have doors that open by themselves, faucets that switch on by themselves, cisterns which flush by themselves, and even, sometimes, lavatory seats that raise themselves. Nothing need be touched. We await only pneumatic levitation: we shall float about on cushions of air, keeping the soles of our shoes pristine and germ-free.

Here I shall explain why germophobia is bad for our health.

What is a germ? This word is a bit colloquial i.e., not very scientific. But if we take a strict definition, then a germ is a 'disease-causing microbe'. Harmless microbes are, however, far more common than pathogenic ones.

We must recognise that bacteria-covered surfaces are entirely normal. In other words bacteria-free surfaces are unnatural.

We must also recognise that, just as plants and animals form ecosystems, so do microorganisms like bacteria and fungi.

We must also recognise that we, ourselves, are substrates for microbial ecosystems. The zillions of microbes that colonise our bodies are what scientists call the 'human microbiome'. As W.H. Auden recognised in A New Year Greeting:

my greetings to all of you, Yeasts, Bacteria, Viruses,

Aerobics and Anaerobics: A Very Happy New Year

to all for whom my ectoderm is as Middle-Earth to me.

What happens after a forest fire? Well, there's a succession of ecosystems. Grasses are the 'first colonisers'; nettles and brambles, say, outcompete these; shrubs in turn outcompete them, until, after decades, the mature ecosystem - the forest - is re-established. The grasses, nettles, brambles and shrubs were immature ecosystems.

A parallel process, albeit a much faster one, happens with microbial ecosystems: when you destroy them, when you create a bacteria-free surface, then, given sufficient opportunity, a mature ecosystem will re-establish itself. But on the way, other, immature ecosystems are seen. There's a whole ecological succession fighting it out down there: struggles between warring factions, treaties, confederations and alliances - but unlike the forest, it's all invisible to us.

Now since microbial diversity is part and parcel of ecological succession, then so, too, are any associated health risks. If the water in an aquarium is a bit dirty, then the fish, living with the mature, diverse microbial community, are healthier. This is because, if the water is abnormally clean, then harmful microbes are not held in check, and will move in. Also, if you really must clean your lavatory very, very thoroughly, then you'd better do so very, very frequently. First colonisers are, after all, faecal bacteria. If you just leave the lavatory alone, then skin-cell bacteria take over. In other words, a lavatory that is given a cursory clean now and then, is less riskier than one that was recently blitzed⁽¹⁾.

These skin-cell bacteria are shed by us. How do they perceive our skin? First, they find it slightly acidic. Second, our perspiration and oil (sebum) combine to form a protective layer - this is the 'acid mantel'. Third, we provide various microclimates. Fourth, we feed them with our sweaty lipids. W. H. Auden again:

For creatures your size I offer a free choice of habitat

so settle yourselves in the zone that suits you best, in the pools

of my pores or the tropical forests of arm-pit and crotch,

in the deserts of my fore-arms, or the cool woods of my scalp.

Build colonies: I will supply adequate warmth and moisture,

the sebum and lipids you need, on condition you never

do annoy me with your presence, but behave as good guests should,

not rioting into acne or athlete's-foot or boil.

Unfortunately these bacteria release vaporous waste by-products: this is body odour. How do we control this? Well, we go into the shower, where we lather away - using alkaline soaps⁽²⁾ - and strip away at the acid mantel, carpet-bombing our microbial communities, leaving a ruined and despoiled microscape. We may feel awfully nice and squeaky clean; but our skin's biochemistry is now abnormal. Human skin, after all, has evolved natural ways to keep us healthy: skin disorders, skin acidity and the acid mantel are all intimately related⁽³⁾.

After leaving the shower, which bacteria are first to colonise this unnatural microscape? I propose here a subversive hypothesis. Perhaps we are vulnerable to sweat-induced odour, not because we are unclean, but because we are too clean. (Consider the forest: if we use a flame thrower every month, we cannot complain that a forest never grows back.) I have no idea whether scientists have investigated this eminently plausible hypothesis, and in any case an objective assessment of body odour is unlikely to exist. It is interesting, though, to discover snippets of advice that 'constant washing and scrubbing' may, actually, worsen body odour. It is impossible to understand why this should be so, without an appreciation of the underlying science. Now and then I come across persons who appear to be conducting this experiment quite unwittingly. Their odiferousness might result from poor personal hygiene - but then again, it might not.

There is a possible reason why this hypothesis remains neglected: corporations want to sell us their products, after all. We've all seen the commercials. A man showers using a certain brand of soap. A beautiful woman approaches, kisses him on the cheek, then turns to look directly at the camera, and so into the eyes of the (male) viewer. The seeds of insecurity are thus planted. 'Your own nose is an unreliable guide. You may well have a problem without knowing it. Buy our product, just to be on the safe side. Woman not included.'

Another microclimate was only too evident to a colleague of mine: he never conversed face-to face. 'My breath could take the paint off a door', he told me. Now he insisted that he'd tried everything, and I've no reason to doubt his honesty. Nevertheless, halitosis is almost invariably adduced to poor oral hygiene. Oral bacteria, as a toothpaste commercial implies, are only incubated by the negligent. This is rubbish. Even after we've brushed our teeth, our mouths contain more bacterial cells than there are citizens of New York City. This is entirely normal. Halitosis might result from poor oral hygiene - but then again, it might not.

The pool of nutrients we provide to our bacteria differ, and so our microbiomes will also differ. Indeed, every human on earth has a unique microbiome. Dogs already know this, of course. Also, mosquitoes head for the most appealing smell - appealing to them, that is. That is why some of us keep getting bitten, when others escape. Some of us, therefore, are more vulnerable to body odour and halitosis than others. That's just the way it is.

Our bodies provide a third and very different microclimate: I refer to the tube that runs the full length of our bodies. The contents of this tube are inside our body periphery, but not inside our bodies - not in a biological sense. Yes: the food within our gut is outside our body. Now, there's no shortage of bacteria inside the gut. In fact there are many times more bacterial cells living on us, than there are cells in our own bodies. (This puts the weighing scales in proper perspective!) Gut bacteria help us in countless ways: they pre-digest our food; they manufacture our vitamins. But they are more than just labour: they are also management: the biochemistry of our gut is controlled by the cells in our gut; the cells in our gut are controlled by the genes in those cells; and those genes are controlled by the bacteria in our gut. The microbiome of our gut is, arguably, another organ: but one that lives on us.

Now here is a perplexing question: the developed countries are plagued by a gamut of autoimmune diseases which remain unknown wherever people still live in primitive environments, or in rudimentary accommodation with dirt floors. It is reasonable, I think, to suspect that modern health problems arise, to some degree, because we no longer live the way we did for several hundred thousand years. We also have a good idea how our forebears lived: we need only look at remote villages in the Amazon or New Guinea or Africa. These peoples do not spend most of their lives inside dirt-free containers called 'buildings'. There are no hygiene fetishists, for whom specks of dust are torture. There are no security guards, patrolling for smidgeons of dirt. We now learn that carpets, indeed - those warehouses of dirt - must be dispensed with: we can keep our homes so much cleaner. Frankly, I'm not so sure I want my home to be any cleaner. I'm not even sure that removing my shoes at the front door is a good idea!

A theory with widespread credence, is that our immune systems must be kept employed; otherwise they go looking for something to do, and they get up to mischief; attacking our own bodies. It is exposure to bacteria that trains, educates, hones and tunes the immune system. But the immune system is not just a means of controlling microbes: it is also, to some degree, controlled by microbes. Humans have, after all, co-evolved with bacteria for several million years; as a result of which we've formed complex, mutualistic relationships: we need microbes to stay healthy, just as microbes need our bodies to survive. But we now live much, much cleaner lives than at any point in human history; and this change has taken place so suddenly, in just a couple of generations. As a result, our immune systems now have problems telling friend from foe; or 'self' from 'nonself'.

Looked at this way, microbes are not just threats; Lilliputian armies with belligerent intent. Rather than continually talking in military metaphors about the microbial world - killing all known germs, along with vast numbers of our friends and allies as collateral damage - we should view the human microbiome as rather more like gardening. We should pull up the weeds; not napalm the entire garden. This is because, in the aseptic sense, 'clean' is bad for us. Cleanliness is a world with microbes, not without them.

References

(1)    Gibbons S.M., Scwartz T., Fouquier J., Mitchell M., Sangwan N., Gilbert J.A., Kelly S.T. (2015). 'Ecological succession and viability of human-associated microbiota on restroom surfaces'. Applied and Environmental Microbiology, 81(2):765-773.

(2)    Tarun J., Susan J., Suria J., John Susan V.J., Criton S. (2014). 'Evaluation of pH of bathing soap and shampoos for skin and hair care'. Indian Journal of Dermatology, 59(5):442-444.

(3)    Ali S.M., Yosopovitch G. (2013). 'Skin pH: from basic science to basic skin care'. Acta Dermato Venereologica, 93:261-267.

Bibliography

Ed Young, I contain multitudes - the microbes within us and a grander view of life. Vintage, 2016.

Lynn Margulis, What is life? Weidenfeld and Nicholson, 1995.

(c) cufwulf

cufwulf@aol.com