to produce conditions to permit the eventual existence of advanced life, just-right life forms at just-right population levels at just-right times had to be progressively introduced, removed, and replaced. The wrong life at the right time or the right life at the wrong time would cause a stagnant lid—the permanent shutdown of plate tectonics. For life to be maintained with abundance, diversity, and longevity to produce the conditions and resources advanced life requires, just-right levels, locations,