Our planet Earth is formed from a protoplanetary disk in a fairly complete form about 3.5 billion years ago. The first primitive life forms, nuclear-free cells, prokaryotes, appear in its waters after the termination of devastating asteroid bombardments (eon Katarchei, duration 600 million years), as well as the formation, as a result of a chilling glancing blow on Gaia, an object the size of Mars, the future companion of lovers Moons…
A blank for the planet Earth…
To explain the appearance of such a large satellite in an ideal circular orbit around the Earth, scientists have to resort to rather complex schemes.
However, for a long one and a half billion years of the stage of development, called Archaea, life forms hardly develop. The top of the current day after day, year after year, hundreds after hundreds of millions of years of the demiurgic process is prokaryotes, bacteria without a nucleus and eukaryotes at all, the basis of plants and animals, which have this nucleus. Multicellular algae, barely visible to the naked eye, appear.
Adenine, Guanine, Cytosine and Thymine – The Four Bricks of Life
All these organisms have a single, universal common ancestor. The genetic set of living things on Earth is exactly the same. DNA is assembled from four biological molecules – adenine, guanine, cytosine and thymine.
Proterozoic (Greek «earlier life») – the longest geological period, 2 billion years, starts 2.5 billion years ago. For one reason or another, oxygen accumulates in the atmosphere. This gas leads to the extinction of almost all anaerobic creatures. The ozone layer is forming. The next trouble is the great Huron glaciation (2.4 – 2.1 billion years ago). Methane combines with oxygen to form carbon dioxide, which is more transparent to reflected light. As a result, the Earth turns into a huge «snowball». It is as cold at the equator as it is in modern Antarctica. Life is preserved in polynyas and reservoirs with melt water.