eli5 why does manure make good fertiliser if excrement is meant to be the bad parts and chemicals that the body cant use

Question

eli5 why does manure make good fertiliser if excrement is meant to be the bad parts and chemicals that the body cant use

In: 7183

Answer 1

Because evolution doesn’t optimize efficiency universally, just locally.

If there’s plenty of nitrogen, for example, in the environment, in the diet, the body doesn’t have to be punctilious about using every last molecule of it. Piss it out. Some plant will pick it up and feed it back to us.

If there are plenty of citrus fruits available, the body may well stop producing its own Vitamin C.