Did you know …
That it was Sir Isaac Newton, patron saint of gravity, apples, luscious hair, and syphilis, who first discovered that the things we put into our main head-hole (foods) become the things that we extrude from our bottom-vent and seat-splitter (1’s and 2’s).
Obviously humans had observed the occasional connection between their input and output when, for example, they recognized a tooth, coin, or partially digested mouse in their chamber pot, but these things were thought to be flukes and coincidence, and the general consensus was that the bulk of the material produced by the human body was the result of, like, spontaneous biogenesis (or whatever the turd equivalent of that would be, anyway). It wasn’t until Newton came along that all that crap was officially considered to be used food.
Newton believed that using oneself as the subject of one’s own experiments was unethical and bad science, so he set up a long-running trial in which he controlled all the food and non-food items that his neighbor consumed, and observed all of the neighbor’s physical output. (The neighbor, of course, had no idea this was happening.) Eventually Newton declared that he could definitively link what we eat to what we blast. The neighbor, sadly, ended the experiment by dying (you can’t really thrive on alternating meals of uncooked rye and stewed prunes, it turns out), but Newton had nearly five years of data at that point, and he felt that was good enough. It had to be, in any case.
The precise mechanisms through which food turns into human garbage weren’t explored until the 20th century (I think that was an Einstein joint), but that’s a story for another day.