What is the chronologic position of man in the environment?

Speaking of the history of life, we have seen periods of millions, hundreds of millions or billions of years. These periods very far from our perception, are difficult to conceive and it is difficult to give them the due weight. Let’s try to realize this concept with the following example:

                 80 years approximately average life;

            5,000 years approximately of history more or less known;

         200,000 years approximately of existence of current  man
                        (homo sapiens);

4,500,000,000 years approximately of life on the planet Earth.

By writing these figure in columns, we can have an initial perception of how recently man has appeared on earth, but how long is four billions and five hundred millions of years? This is a figure so large to have difficulty even in reading it, a figure that surely we cannot perceive in relation to our life.
To make more comprehensible the time of our planet, a curious game can be done that relates life on Earth to a day, which is the unit with which we are familiar:

           00:00 hours the planet Earth is formed;

around 04:00 p.m.: the first protists;

around 08:00 p.m.: the first aquatic animals;

around 10:00 p.m.: the first terrestrial animals;

around 11:00 p.m.: the first mammals;

around 11:40 p.m.: the appearance of the first prosimians;

around 11:53 p.m.: the appearance of the first great apes;

around 11:58 p.m.: the appearance of the first hominids;

around 11:59:54 p.m.: appearance of the homo sapiens;

around 11:59:59:94 p.m.: the birth of Christ.

Before this game, certainly none of us would have assumed that the prehistory began about six seconds before midnight and that the era “after Christ” of current calendars is a small fraction in hundredths of a second.
All the existence of humanity is only a wink of an eye compared to the history of Earth and the modern era itself is only a thousandth part of human history.

ROYAL BOX
  WILLARD FRANK LIBBY