There are also challenging problems with the idea that chemiosmotic coupling arose very early in evolution. One is the sheer sophistication of the mechanism. We have already paid our dues to the giant respiratory complexes and the ATP synthase – incredible molecular machines with pistons and rotary motors. Could these really be a product of the earliest days of evolution, before the advent of DNA replication? Surely not! But that’s a purely emotional response. The ATP synthase is no more complex than a ribosome, and everyone is agreed that ribosomes had to evolve early.
