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Origins of Mankind (Somewhat Experimental) (Pre-History)
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Ishmael


In: Toronto
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So what makes humans unique in a way that would impact their susceptibility to disease from ingested water---and perhaps particularly, lung disease---is rather obvious, when you know about it.
Humans are the only mammal that cannot breathe and swallow at the same time, and we are the only species that can choke on its own food. The reason? The lowering of the voice box in our throats (during infancy) enables us to create the enormous range of sounds used in producing language; but this lowering of the voice box comes at a big cost in adulthood.

-- Did You Know? – Human Origins Facts
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Mick Harper
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In: London
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Very good.
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Ishmael


In: Toronto
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Before we get into the evolutionary implications of this discovery, we must first take a moment to consider why this trait is so very dangerous. The reason has little to do with choking. It is rare that a human being chokes to death (though, as a child, I came close). Those who come close to choking are typically saved by their kin (as I was). That risk is small to non-existent. That means no evolutionary pressure against the descent of the larynx can come of the choking hazard.

Yet human beings are literally the only animal for which nature has allowed the larynx to descend! It must be incredibly dangerous! Why?

The answer is, of course, water.

When an animal drinks water---when a dog drinks from a puddle---that water goes straight to the stomach. The stomach is designed to handle just about any shit that gets poured down the gullet. Bit of excrement and nasty bacteria comes in---some acids, heavy stomach walls, and antibiotic fluids will take care of that right away and allow that good H2O to be absorbed as needed.

But what happens when the water misses the stomach? In most animals that's almost impossible. But not in humans. In humans, the water can go down the wrong way. That wrong way heads straight to the lungs.

If shit water enters the lungs, there's nothing there to defend against whatever garbage came in. No protection. The body must engage its secondary defences against infection. So we get sick. And, if we are lucky, we get better. Or we die. Often we die. We die in such proportions that nature has literally never allowed any other animal to adopt such a nonsensical design.

And yet, without this design, no animal can do what we do best.

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Ishmael


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I should add that, as can be seen in the posted illustration, any bacteria in a human mouth has an unobstructed route available, through a massive opening, directly down into the airway. The mouth in other animals is typically a closed chamber and, even when open to allow the passage of food and water, does not lead directly to the airway.

I suspect that it is these differences that make human beings particularly susceptible to bacteriological infection from the ingestion of impure water.
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