Your body is insanely complex.
Humans, with all of our scientific knowhow and the aid of vast compu- tational power from supercomputers, have just reached the point of being able to model a single cell of the world’s simplest organism. We’re still a long way from having a comprehensive model for a single human cell, let alone modeling, from the bottom up, how individual cells interact, or how entire organs signal back and forth with each other, or how the human brain works in its entirety, or how it interacts with, influences, and is influenced by the other tissues of the body, and how we interact with other complex organisms (each other) and our environment.
We, as a species, know a lot, and we’re quickly learning more every day. But we still have a long way to go to understand all of the workings of a single one of our cells.
Just let that sink in for a moment.