Progress and success are always relative. When the land was unoccupied by animals, the first amphibian to emerge from the sea could get away with being slow, lumbering, and fish-like, for it had no enemies and no competitors. But if a fish were to take to the land today, it would be gobbled up by a passing fox as surely as a Mongol horde would be wiped out by machine guns. In history and in evolution, progress is always a futile, Sisyphean struggle to stay in the same relative place by getting ever better at things.