• itslilith@lemmy.blahaj.zone
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    1 month ago

    Not true, topolgically the route

    left nostril -> sinus -> right nostril

    is another hole. So is

    any nostril -> sinus -> mouth.

    ears have the eardrum, so they don’t count.

    For the more formal definitions of topological holes, look up Betti numbers, I think there’s a VSauce video about it? For humans, the number of holes is at least 3 (but I’m sure I’m missing many more holes). Unless you’re missing the entire septum.