Earth was struck by Mars-sized Theia, which vaporises the surface and blasts it into space. The rejected materials were then used to create the Moon. Massive outer-space bodies then continued to hit Earth for the next 1.5 Billion years.

After Earth has cooled down and has water, it may have contained the rocks to help from the planet => Earth was born wet.

The first cell was derived from self-reproducing RNA molecules. The replication of these organisms requires resources like energy, space, and smaller building blocks, which soon become limited, resulting in competition

Cells resembling prokaryotes appear. These first organisms are chemoautotrophs: they use carbon dioxide as a carbon source and oxidize inorganic materials to extract energy. Later, prokaryotes evolve glycolysis a set of chemical reactions that free the energy of organic molecules such as glucose.

One key organelle is the nucleus: the control centre of the cell, in which the genes are stored in the form of DNA.

The Cambrian Period marks an important point in the history of life on Earth; it is the time when most of the major groups of animals first appear in the fossil record. This event is sometimes called the "Cambrian Explosion," because of the relatively short time over which this diversity of forms appears.

Origin of sexual reproduction. Many protists reproduce sexually, as do many multicellular plants, animals, and fungi.