They say every atom in our body once came from a star. In fact, all matter that exists resulted from the Big Bang, that moment of cosmic conception. Since then, all that existed still exist in one form or another. In other words, all existing matter cannot be destroyed or created. It can, however, transform, like from something that is solid to energy. This is the law of conservation of mass. Or, as the ancient Greeks would say, “Nothing comes from nothing.”
To simplify, atoms, molecules, proteins, cells, are all constantly recycled. Water evaporates, the vapor coalesces and then form raindrops. Old cells in our body decays and is absorbed by other cells, which uses parts from the old cells to form new cells. A plant is eaten by an animal, which when it dies goes into the ground and contributes to the nutrients of soil, which in turn is consumed by another plant. It’s a complex, mind-boggling, cycle. But the idea is this: everything is a food source for something else.
Thinking in that context, here’s a thought experiment: What if humans one day become a food source for something? Beyond being food for worms after we die, that is. What if humans are farmed? After all, we farm animals for that purpose of managing our food supply. What if one day an alien race comes to Earth to round us up into farms and slaughterhouses? Of course, we would attempt to fight back. But what if the aliens’ technology (i.e. weapons) are so advanced that we are helpless? As helpless as the cattle, pigs and chickens that we farm?