an exponential process (of life complexity in this case) looks the same at any scale. The Earth has existed for 4B years, life is ~3B years, life as a cell with nucleus ~2B (yea, 1B years to develop nucleus :)
i kind of see it here. The evolution speed depends on the speed of generating of changes and on the speed of selection of the generated changes.
Wrt. the speed of generating of changes. The more complex a system (i.e. types and number of actors/components and relationships between them) - the more diverse set of small gradual changes/variations to components/relationships/behaviors can happen while the system will still be functioning. In particular it is applicable to biological systems, ie. single cells, colonies, multicell organisms and various groups/societies of it. For example, in general, 2 different species of cells can produce more diverse set of natural variations than 1 species even if the total number of cells is the same in both cases. An example at different scale - one science - philosophy of Ancient Greeks has become a multitude of sciences through the same process of branching/specialization and the speed of this process is proportional to the number of branching/specializing sciences. Following the same principle - there is no way US tax code (or the law in general :) will become simpler anytime in the future :)
Technological advancement tends to follow that pattern, and I imagine many evolutionary changes do, too.