Somehow it doesn't suprise me that a mammal's mouth is both for eating and vocalizing: it is easy to imagine the vocal capacity as layered on. Nor that my mouth can be used as an alternative to the nose for breathing: redundancy for meeting the most immediate need through double purpose makes perfect sense. Nor that smell is co-located in the nose. I could go on.
But I suppose I am suprised that ingestion and respiration converge in the throat, and that liquid elimination and reproduction converge in the same organs. After all, each of both pairs of functions are basic - and they don't seem to do anything for one another but potentially interfere. (We have all had the experience of nearly choking on a swallow of water that goes down wrong.) The idea that this is a matter of merely efficient doubling up doesn't satisfy.
But it does make for an elegant double-wye symmetry. One imagines a shape like this: >--< ; and that is, after all, an anthropomorphic configuration.
1 comment:
It's interesting to think about. The more mucous membranes, the more avenues of infection an organism presents. On the one hand, most reptiles and amphibians have only a cloaca for all elimination and reproduction, whereas humans have up to three holes for the same. On the other hand, fish and amphibians keep their gills exposed to the outside world without any filtration or invader-trapping mucus intervening (though they also can't suffocate themselves by choking on their food), whereas our own alveoli are buried behind the successive gates of our mouth/nose, pharynx, epiglottis, and trachea. So we've diversified our vulnerability on the bottom but consolidated it on the top.
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