One of the challenges in studying evolution is getting a mental picture of the time scales involved. There is evidence for immense change all around us, but the length of a single human lifetime is tiny when compared to the amount of time it took for humans and other primates to evolve from the very first primate ancestors. One way to understand the pace of primate evolution is to think about it in different terms.

The following charts are constructed as if the entire 4.6 billion year history of the earth has taken place in a single 30-day month. There is also a chart that shows the history of the earth since the extinction of the dinosaurs 65 million years ago as a single month.