BIOLOGY

Sun (and solar system)

6 BCE

It formed about 4.6 billion years ago when a dense region of a molecular cloud collapsed, forming the Sun and a protoplanetary disc. The Sun is a typical star that maintains a balanced equilibrium by the fusion of hydrogen into helium at its core.

Universe (Big Bang)

5 BCE

The Big Bang is understood as the beginning of the universe, that is, the initial point at which matter, space and time were formed.
The standard model states that the universe was in a state of very high density and temperature and then expanded.

Life (Prokaryotic cells)

4 BCE

The first cells were most likely very simple prokaryotic forms. The eukaryotic cell might have evolved when a large anaerobic (living without oxygen) amoeboid prokaryote ingested small aerobic (living with oxygen) bacteria and stabilized them instead of digesting them.

Multicellular organisms

3 BCE

The earliest fossils of multicellular organisms include the contested Grypania spiralis.
These are formated with evidence of multicellular traits.

Eukaryotic cells

2 BCE

We have registered the first eukaryotic cells in Proterozoic. We can observe the first cells covered with membranes, actually, the majority of cells are of this type.

Primitive Earth

1 BCE

It's named "Primitive Earth" to the Earth in his first 1B of years, in this time, the earth was formed by lots of volcanoes, magma oceans, lots of meteorites...
The distance of the Earth to Sun, mixed with the materials that appear with the meteorites, make that life can appear on Earth.