I agree that cooking is a form of digestion, but that is not what I was thinking when I made my comment. We are walking tubes. The cavity inside of the tube is

I agree that cooking is a form of digestion, but that is not what I was thinking when I made my comment. We are walking tubes. The cavity inside of the tube is still external to the tube itself. This is a video that partially explains the concept. https://youtu.be/vuIlsN32WaE https://youtu.be/vuIlsN32WaE