Contact with representatives of extraterrestrial civilizations has not yet been established, because most of them died at the stage of microbial life. Planetary scientists write about this in their publication in the journal Astrobiology.
Experts say that when visiting planets potentially suitable for the development of life, a person will find there only the remains of the simplest microorganisms. Most of the finds of fossilized remains of representatives of other civilizations in the Universe belong not to developed creatures and not even to animals that have evolved over billions of years, but to simple single-celled organisms.
Some scientists argue that intelligent life is a rarity in the Milky Way. In addition, on exoplanets, even the simplest forms of life perish, not having time to go through the stages of development to multicellular organisms.
So, despite the fact that in our solar system, in addition to the Earth, Venus and Mars are located in the habitable zone, for 4 billion of the development of terrestrial life, it became too hot on the first of them, and too cold on the second.
Experts say that many living organisms perish without having time to conquer their own planets, having learned to maintain the so-called greenhouse effect on them and control the climate and geology.