How Many Holes Does a Human Have?

A human body has far fewer “through holes” than everyday anatomy suggests—at a specific minimum size, it behaves like a “seven-hold doughnut” rather than a Swiss-cheese bundle of openings. The key move is setting a measurable threshold for what counts as a hole: around 60 microns wide (about the width of a human hair). At that scale, many common openings—nostrils, ears, pores, nipples, and sinuses—don’t function as continuous passages end-to-end; they mostly dead-end, narrow, or block passage.

The transcript starts by challenging the intuitive “how many holes?” question. At molecular and subatomic scales, “holes” become meaningless because matter is not a solid object with empty space; it’s a constellation of atoms and molecules. Even at the biological scale, not all gaps behave the same. A 60-micron “magic spaceship” could enter certain surface openings, but it would be stopped by structures like capillaries, the eardrum, or the conjunctiva. This distinction leads to two categories: through holes (GI tract-like pathways that connect an entrance to an exit) and blind holes (pores, hair follicles, urethras, sinuses, and other cul-de-sacs that can be entered but not traversed at that size).

From there, the discussion turns philosophical—then turns mathematical. “Hole” is treated as a fuzzy everyday word, illustrated by molding a shape from a glass to a bowl to a plate and watching the “hole-ness” of the object change without any obvious physical pinching or gluing. That ambiguity is resolved using topology, the branch of math focused on properties that persist under continuous deformation. In topology, a doughnut and a coffee cup can be treated as equivalent because one can be stretched into the other without cutting or gluing; such transformations are called homeomorphisms. Under these rules, blind holes can be erased by deformation, but through holes cannot.

Counting through holes becomes a topological exercise: find a homeomorphic shape with an easy-to-count number of through passages. The body’s connected external orifices—mouth, nostrils, and tear ducts—plus the GI tract pathway and related internal connections yield a baseline of seven through holes at the 60-micron scale. The transcript also notes that openings don’t automatically equal holes; a straw, for example, has two “ends” but only one continuous passage, so it’s topologically one hole.

Finally, the count can increase with anatomical variations. Piercings that pass through a through hole add holes; supernumerary lacrimal punctum (extra tear-duct openings) can add additional through holes; and accessory ostia—extra openings connecting sinuses to the nasal cavity—can add more. Most people won’t know their exact total without imaging, but the baseline claim is clear: millions of blind holes (at least five million) and seven through holes at birth, with possible additions depending on individual anatomy and medical history.