It is not known exactly how the first living beings were. They are believed to be microscopic, much like the simplest microorganisms today.
The chemistry explains how
Scientists, using the chemistry expertise, study volcanoes and laboratory experiments, suggest that the first living beings appeared on our planet about 3.5 billion years ago, from chemical reactions that occurred between the gases that formed the primitive atmosphere , which was very different from the present.
It was around 1920 that two scientists, the Russian Aleksander Ivanovich Oparin (1894-1980) and the English John BS Haldane (1892-1964), launched a hypothesis to explain the origin of life .
For them, the primitive atmosphere was composed of the following gases: methane, ammonia, hydrogen and water vapor. With the energy of the electric discharges during the storms and also of the ultraviolet radiation coming from the Sun (at that time there was still no ozone layer), the gases have been combining and giving rise to new substances, including organic substances that are found in the body of living beings (sugars and amino acids). With rainwater, these substances fell into the earth’s crust and were dragged into the oceans.
In the oceans, these organic molecules have been grouped together and formed molecular agglomerates that became known as coacervates .
These coacervates were able to absorb and exchange substances with the external environment. Later, they acquired the ability to make copies of themselves. At that moment, the first living creatures would have appeared, which, although primitive, were capable of reproducing, giving rise to other living beings.
Throughout this time, they have been changing, evolving and originating the immense variety of species, including man. The planet’s biodiversity is its greatest asset.
How were the first living beings
Scientists believe that these living beings were, at first, heterotrophic and fed on the organic substances that were abundant in the early oceans. By doing this, they would get the energy they needed for their vital processes, grow and reproduce.
After millions of years, the number of these living beings has increased greatly, new species have emerged and the stock of available food has become scarce for all.
It is likely that autotrophic beings , that is, capable of producing their own food using solar energy and simple substances such as carbon dioxide and water ( photosynthesizers ), were released by evolution, thereby releasing oxygen into the atmosphere.
Through this activity, oxygen accumulated in the atmosphere, making it more similar to the current one.
Since the birth of these first living beings, modifications have originated different species. Some of them exist to this day; others, already extinct, were only known through fossils.
All this, described thus, so quickly, seems simple. But we must not forget that the Earth is 4.6 billion years old and that the oldest fossils are found in rocks about 3.5 billion years old. This means that the formation of the first living being may have taken more than a billion years!