The sphincter is not a closed surface, topologically, so it’s technically a hole even if it puckers so tight you couldn’t drive an ice pick up there with a sledge hammer.
When your head’s up your ass, does that make you a cruller?
Similarly, ISTR that the length/width/height dimensions quoted for Noah’s Ark are in roughly the same proportions as the human body (tho’ differently oriented). So not only are we ambulatory doughnuts, but we are roughly the same shape as Noah’s Ark.
For a really thorough count of the number of through-apertures on the human body, don’t forget to include piercings.
Nice!
“MMMmmmm! Long pork!”~~Homer Simpson.
A Human is not a donut. Nostrils and ears connect to the throat. So a human has 5 distinct holes.
And don’t forget piercings.
You could also argue that each hair is a separate object topologically, but still part of the human.
If stuff can get in, there’s at least one hole there.
Actually, if you want to get really picky, humans are mostly empty space filled with a lot of electrons and nuclei. So no, we’re not donuts–we’re not even connected.
Only if the eardrum is perforated. The eustacian tubes run from the back of the throat to the middle ear, which is separated from the outside world by the normally airtight tympanum.
Ah ha! Here’s the real crux of the question: how does one define a “hole” in this context? I think we need a definition which excludes the spaces between atoms and molecules, since common sense dictates that we think of these as being contiguous, for our purposes.
The hole in your mouth is a wider space between molecules than elsewhere in your body. I guess you could set a minimum size, but if you’re getting into topology, it’s not fair to expect common sense to have any input.
I don’t know about you, but if I plug my nose and close my mouth, I can blow a very small amount of air out of my ears. I can depressurize my ears in an airplane with my nose and mouth closed. So I think ears are only airtight in the same way that your mouth is airtight when it is closed.
Or maybe we are all just wrinkles on a contiguous 13-dimensional M-brane?
But how much salt would it take to cover him?
I used to be able to, after one of my eardrums was ruptured in a fight, but once that healed up it was sealed. However, I just thought of another set of holes we’ve overlooked: At the bottom of each eye is a tear drainage tube called the nasolacrimal duct. These connect to the nasal passages, and are therefore connected to the mouth and throat.
Do you get into a lot of fistfights at math conferences? 
I think you’re talking about gastrulation, which happens pretty early in embryonic development and forms the archenteron, which becomes the digestive tract. The neural tube forms later in a completely different process.
It makes you a Klein Bottle.
HA HA HA HA HA!!!
Or a Klein Bottle.
Much like me…
:smack:
Interesting how no one posted that joke for 24 hours, and then two of us did it within ten minutes.
I’m still laughing, by the way.
Since the mouth attaches to two other exits (nasal and anal), we are donuts with a sidehole, topologically speaking (or more sideholes if we consider the tear ducts). True genus 2 donuts would require extra separate holes. I suppose stigmata could make you genus 5!