Magnificent Evolution, Mostly

You can’t work in Emergency Medicine without being regularly awestruck by the human body. The way it functions, on both macroscopic and molecular levels, is so improbably complex it’s hard for us to get our top-heavy brains around it. And, quite frankly, we haven’t. We are unearthing new physiological principles all the time. Some recently discovered entities are so fundamental you wonder how we ever got on without knowing them; others are plain outlandish. Examples are the glycocalyx being the centurion of the blood vessels rather than traditional Starlings forces, the glymphatic channels being tiny pipes through which our brains are cleansed with CSF while we sleep, the testes can olfact, the lungs make platelets. Our organs are having conversations with each other that we owners and researchers can barely hear.

Even more astounding is that it took evolution, with its one lucky, painstaking step at a time, to get everything so intricately interconnected.

But evolution has not always been a smashing success. Although our evolutionary improvements propelled us to our current footing as dominant species, some of these changes are not always suited to our contemporary lives. We get hiccoughs, possibly harking back to our ancestral lungfish cousins who had to swap quickly between gills and lungs. We get fat – slaves to an ancient mix of hunger hormones and sneaky tastebuds singing out for fat and sugar. We get goosebumps, trying to keep us warm by raising our no longer existent fur. And, damn it, we choke. We snore. We obstruct. The price evolving hominids had to pay for the magic of speech, our penchant for eating meat and making space for our globulous frontal lobes is something called klinorhynchy. Our faces have flattened. In addition, our trachea and esophagus have both been pulled down, and are now preposterously vertical, the air tube at perilous risk of permitting entry to things only meant for the food tube.

And sometimes we ignore the benefits evolution has bestowed upon us (surprise me, I hear all practicing Emergency Physicians say). Sitting along the back row of the tongue, like a military phalanx, are the tastebuds that declare bitterness. Teleologically it is thought that this prevents us ingesting dangerous fare. Most sensible creatures spit out poisons and toxins before they get a chance to be absorbed, or even worse, make their travelling way down the esophagus. But humans self-harm in record numbers, with toxic ingestion one of the more common methods. Humans, who have no intentional predators but themselves, swallow stuff.

Several recent cases down in our Australian back-blocks had me thinking about what happens when certain substances are introduced to the oral and esophageal mucosa, substances which really have no business being there. We have seen hydrogen peroxide swallowed only to effervesce into voluminous bubbles of oxygen, dissolving bends-like into the vasculature. We have had our department evacuated following a patient’s ingestion of aluminium phosphide which had transmuted into the freakishly toxic phosphine gas. We have managed scarred esophagi following copper sulphate ingestion. We have, like most places, managed the long tail of patients who had hoped to end their days by swallowing alkali, only to suffer the horrendous sequelae of mucosal corrosion. The human aerodigestive tract was not Darwinianly designed to give passage to such matter.

This, of course, leads us to ponder on war. You are not the only one to wonder what the difference is between phosphine and phosgene gas. Phosphine is a garlicky, dense, highly flammable gas with escalating vaporous toxicity; great for pests, terrible for man, a nightmare for ED logistics. Phosgene was designed for dye, has a mouldy hay smell, is savagely toxic to respiratory mucosa, and was latterly introduced as an agent for gas warfare. There are few who are not moved by Wilfred Owen’s World War One poetry. In fact, I think Dulce et Decorum Est was the first poem I ever read that bypassed any critical ability I had to say this. This is what writing can achieve. This is beauty and song and prosody and the suffocating horror of the world all in one. In our context here, though, what gas is Owen referring to?

Gas! Gas! Quick, boys!—An ecstasy of fumbling,

Fitting the clumsy helmets just in time;

But someone still was yelling out and stumbling

And flound’ring like a man in fire or lime…

Dim, through the misty panes and thick green light,

As under a green sea, I saw him drowning

Although phosgene was the predominant chemical agent of warfare at the time Owen penned this (the end of 1917), the description smacks more of chlorine, with its sea of green. Chlorine, although not particularly deadly, was commonly used as a debilitating tit for tat by both sides. The most populous war grave is near Trieste, at Redipuglia; a somber, cold stone monument, with 110 000 young Italian men buried beneath it, many the mute victims of the Germans who smothered the Italian front in chlorine, and then capitalized on the fleeing, blinded, choking troops by slaughtering them; a signature move of war.

Thus, not only have we not evolved enough to prevent us swallowing and inhaling strange and bizarre molecules, we were not evolved for chemical warfare. Or any warfare really. If perhaps we could let those in charge know.

About the author

Dr Michelle Johnston is a consultant Emergency Physician who works at an inner city hospital. Mostly her days consist of trauma and mess. Also, she writes.

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