Ever since then, all descendant vertebrates have had the forward end of the digestive system and the forward end of the respiratory system very much involved...

Ever since then, all descendant vertebrates have had the forward end of the digestive system and the forward end of the respiratory system very much involved with each other. This manifests itself in the human body with a crossing of the two systems in the throat.

quote by George C. Williams
Submitted by Lucian Velea
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