> How much of what we are is a product of what we've built up?
At least 1.5% by mass
About 3% of our body is nitrogen, about half of it comes from fertilizers made using Haber-Bosch process, an industrial chemical process that is unlike anything found in nature.
But if we count differently and consider agriculture in general as "something we've built up", then it is about 99.9%. It is estimated that the earth would support about 10 million hunter-gatherers, we are nearing 10 billion.
At least 1.5% by mass
About 3% of our body is nitrogen, about half of it comes from fertilizers made using Haber-Bosch process, an industrial chemical process that is unlike anything found in nature.
But if we count differently and consider agriculture in general as "something we've built up", then it is about 99.9%. It is estimated that the earth would support about 10 million hunter-gatherers, we are nearing 10 billion.