Evolution

Earth's formation part 1: stars (sun)

4500 BCE

Just like the formation of the Earth and other planets stars take a long time to be be born. They’re essentially formed from clouds of gas in space. We know these as nebulas. Over time gravity causes the atoms of gases and space dust to start coming together and gathering, this way they gain more mass and with it stronger gravity. This is a process that can take millions of years. In time the gravity causes the gases, mainly hydrogen to fuse in a nuclear reaction and a star is formed.

Earth's formation part 2

4500 BCE

After the Sun was formed we know from observations and other indirect evidence that there were left over gases and heavier elements. The gravity of the Sun helped to flatten these left overs into a disk and start to fuse them together. This created the planetesimals and planetoids which would later make up the planets. Over time these planetesimals would collide creating even bigger masses. It was in this method that the Earth was eventually formed.

The first organic molecules

4000 BCE

Different experiments tried to prove that we can obtain OM from IM. Miller’s experiment based on Oparin and Haldane theory succeed. He simulated the primitive atmosphere. A week later he found 10% of organic compound in the water.

Life appears. Prokaryotic cells.

3500 BCE

The way from the primordial soup to the first prokayotic cells is still uncertain. Organic molecules, formed in the atmosphere, were brought onto the Earth by the rain making the primordial soup. They associated making long chains. Some of them became protocells (macromolecular complex and organelles circled on a cell membrane.) These protocells slowly developed till they became living structures.

Oxygen in the air

1800 BCE

One of the oldest organisms on the Earth are the stromatolytes which appeared 3500 million years ago. They are colonial microorganisms They are the ones that transformed the primitive atmosphere.
They were photosynthetic so they use the solar energy and innorganic matter (water and carbon dyoxide) to synthesize organic matter. In this reaction oxygen was released. They reproduced a lot so the atmosphere composition changed and it became oxydyzing.

Oxygen disaster

1800 BCE

This change made the apparition of new forms of life which couldn’t transform the solar energy into chemical , the heterotrophic possible. These organisms obtain their energy burning organic matter with oxygen (21% of the new atmosphere)
But, this oxygen was toxic for some of the photosynthetic forms that originated it (the oxygen disaster) and disappeared this was the first big extinction.

Fisrt eukaryotic cells

1400 BCE

From prokaryotic to eukaryotic cells that’s the endosymbiosis hypothesis. It talks about the formation of eukaryotic cells from the union of prokaryotic cells. Depending on the type we can have plant cells or animal cells (Autotrophic and Heterotrophic). And then, cells gathered making colonies that would bring to multicellular organisms where cells perform special and concrete functions.

Multicellular organisms. Cambrian life explosion

600 BCE

Eukaryotic sexual reproduction gave to them the capacity of exchanging information and adapting to the changes in the environment. Finally, cells gathered making colonies that would bring to multicellular organisms where cells perform special and concrete functions.
The Cambrian explosion was the sudden appearance and rapid diversification of macroscopic multicellular complex organisms in the beginnings of the Cambrian period.

First vertebrates

500 BCE

The vertebrates have managed to adapt to different environments. They have managed to evolve in the sea and to go on later to the terrestrial environment. The vertebrates originated during the Cambrian explosion, at the beginning of the Paleozoic, close to other many groups of animals. The most ancient vertebrate is the Haikouichthys, with an antiquity of 525 million years.

Dinosaurs and mammals coexist:

200 BCE

During the Mesozoic period the appeared the first birds and mammals. A period that both species coexist, dinosaurs and mammals. Also in the vegetal kingdom they evolve the plants with flowers. But finally a big cataclysm of a meteorite caused the extinction of the dinosaurs.

Dinosaurs’ extinction

65 BCE

Although the cause of their extinction is still a mystery, climatic change, diseases, changing plant communities, and geologic events could all have played a role.
A recent explanation, supported by many scientists, suggests that dinosaurs died out soon after a huge meteorite crashed to Earth near the Gulf of Mexico. A giant meteorite, that could have landed with an impact that kicked up enough dust and debris to block out sunlight for a long time

Primates and Australopithecus.

4 BCE

Apes such as the gorilla, gibbon and chimpanzee appeared
The apes were primarily quadrupedal, or four-footed.
The apes and man are are primates and close relatives The hominids appeared: A hominid is any of the two-legged primates. Australopithecus is an extinct genus of hominids. The Australopithecus is the earliest species of Australopithecus, and lived in eastern Africa. Its brain was about the same size as a chimpanzee.

Homo habilis

2 BCE

Homo habilis, an upright East African hominid having some advanced humanlike characteristics developed from the Australopithecus. Homo habilis is considered to be the oldest human-like species of Homo.

Homo erectus

1 BCE

Homo erectus meaning "upright man" appeared
These are called bipedal, or two-footed, upright walkers
The term "erectus" refers to the upright posture.