One of the best and most frequently used methods to illustrate the age of the Earth, and the timeline of events is to use the 24 hour clock method. Where the timeline of the Earth, from formation to present day is given as a full 24 hour day and events are marked along the hours and minutes where they have occurred along the way. In this method, the most simple forms of uni-cellular life begins to appear around 4 am on the clock. Little else changes in terms of life forms until around 1pm where the first eukaryotes start to appear. That's half of Earth's existence already, and only the most simple forms of life have developed. Around 5.30 pm the first multicellular life starts to appear. But it's not until after 10 pm that life starts to emerge from the water onto land. The dinosaurs arrive around 10.45 pm, mammals not until around 11.40 pm! It is not until around the last two seconds of the day that modern humans arrive on the scene. In the last two seconds every moment of human existence has taken place. That's some mind bending perspective!