22 June 2019 - oxygen 2

Why do animals exist? For the same reason that you hire somebody else to fix your roof: Because specialization works. Suppose there were an animalplant organism—when on Earth would it make sense to both spend energy to make materials, freeing oxygen, and gather outside materials to combine with the oxygen to get the energy back? For a plant, unlike an animal, energy is not the limiting factor; photosynthesis is about 1% efficient, far less than a solar cell, because plants are optimized to use the rare stuff efficiently, not the common stuff. And that’s good for us, because energy-rich plants construct themselves out of energy-rich materials (cheap for them), which means they burn, which means we can cook our food, which means we can extract more energy from our food than other animals, which put us on a path to evolving bigger energy-hungry brains, so that we can build roofs that need fixing.