Approximately 4,600 million years ago, our planet began life as a fiery ball of gas. As it cooled, the Earth’s crust, the atmosphere and the oceans slowly but surely took shape. 3,800 million years ago, the earliest life forms appeared in the oceans. These were simple, unicellular organisms without a nucleus; we call them ‘prokaryotes’. Around 1,700 million years ago, they acquired a nucleus and submicroscopic organs and became what we now call ‘eukaryotes’.
The first multicellular organisms appeared approximately 1,000 million years ago. The oceans at this time contained algae that produced so much oxygen that the atmosphere gradually became saturated with it. Slowly but surely, other organisms adapted to cope with the toxic oxygen. Multicellular organisms took on ever more complex forms. The Earth became populated by a huge variety of life forms. Most came and went over time. Some survived. Algae, fish, plants, reptiles, dinosaurs and mammals... Man is one of the most recent products of this process of evolution.