Some people unfamiliar with our anatomy might think of it as “efficient,” yet in an accounting of resources, it is rather inefficient. Humans have two lungs with excess capacity in each. We have two kidneys, yet we only need one. We use a small fraction of our total brain capacity at any one time. Having all of these spare parts and needing to consume the resources to sustain them is grossly inefficient. Yet, obviously, spare parts are necessary for our survival.
