CHEMOSYNTHETIC THEORY: THE EMERGENCE OF LIFE ON EARTH - SCIENCE - 2025

The chemosynthetic theory, also known as the biosynthetic theory or the physicochemical theory of the origin of life, is based on the hypothesis that life on our planet originated from the grouping (synthesis) of very primitive molecules at the origin of time. and that were becoming more complex until the first cells were formed.

This theory was developed almost at the same time -between 1924 and 1928-, but separately by the scientists Alexander I. Oparin (Russian biochemist) and John BS Haldane (English biologist), confirming the Big Bang theory and overturning the theory of spontaneous generation, a prevailing belief since ancient times.

Among the contributions to the work of these two scientists, the participation of the Mexican pharmacist Alfonso Luis Herrera stands out, who carried out studies on the origin and evolution of life on earth and who is considered the creator of plasmogeny, a science that studies the origin of protoplasm, that is, the origin of life.

His studies were published abroad and served as the basis for Oparin and Haldane to develop their theory, which was also nourished by geological, paleontological and biochemical studies.

At present, the chemosynthetic theory is the most accepted by scientists. In it, the origin of life is explained from the chemical evolution and physical phenomena of matter.

Chemosynthetic theory: how did life arise on earth?

According to the Big Bang theory, the earth arose about 5 billion years ago from a cloud of hydrogen gas. Simultaneously, the sun and the other planets of the solar system originated.

At first, the temperature of the earth was extremely high, but little by little it cooled down and the primitive oceans began to form.

Back then, the atmosphere was very different from today. Water vapor, methane, ammonia, carbon dioxide and hydrogen predominated.

Unlike what happens in our days, in that initial phase there was no ozone layer, so all kinds of radiation reached the earth's surface, including ultraviolet and infrared rays.

In addition, there was a lot of energy produced by constant volcanic eruptions, lightning and lightning.

First organic compounds

Under this scenario it is very possible that the first organic compounds in these primitive oceans, among which were carbohydrates, lipids and some amino acids, have been formed and destroyed over and over again until, finally, they found some stability to evolve.

During millions of years these substances were chemically combining with each other, forming increasingly complex substances that were delimited by a membrane.

Protobionts

Oparin called these substances protobionts. Their existence lasted for millions of years and, with the passage of time, they acquired characteristics of living beings, performing functions such as nutrition and excretion. They also began to reproduce, which implied the appearance of nucleic acids that carried the genetic information.

Evolutionarily, protobionts preceded the first simple and straightforward cells that emerged thousands of years later. It is believed that the first living things that appeared on earth were very similar to bacteria.

These extremely simple primal beings evolved and became more complex until they became multicellular organisms.

Miller and Urey's contribution

In 1953, American chemists Stanley L. Miller and Harold Clayton Urey tried to reproduce in a laboratory the conditions suggested by Oparin and Haldane in their theory. Miller and Urey created an apparatus in which they reproduced the conditions of the primitive earth posed by the chemosynthetic theory.

The apparatus consisted of several containers connected to each other. In order to recreate the conditions of the earth's early atmosphere, these scientists placed two electrodes, water, methane, ammonia and hydrogen, in the containers.

Using the electrodes, they produced electrical discharges that set off sparks similar to those generated by lightning.

The water that simulated the primitive oceans was brought to the boiling point. A multitude of inorganic molecules were introduced into it from which simple and simple living beings had to be formed.

The experiment lasted for several weeks, at the end of which the scientists noticed that some substances had accumulated in the water and on the walls of the containers.

When analyzing them, Miller and Urey realized that they were several organic compounds, including four different amino acids, which are involved in the formation of proteins.

With their experiment, American scientists were able to verify that organic compounds were formed from inorganic compounds.

In this way they opened the way to demonstrate that pre-biological evolution, as proposed by Oparin and Haldane, was possible.

Since then, experiments similar to those of Miller and Urey have been carried out, but varying the amounts and types of gases. Also, in some experiments, various energy sources such as infrared and ultraviolet rays have been used.

Most of these experiments obtained a great diversity of organic compounds that are part of living beings.

In this way, the chemosynthetic theory has been partially proven.

Limitations for testing

The experiments carried out to verify the chemosynthetic theory have succeeded in demonstrating that it is feasible that the origin of life was just as Oparin and Haldane put it. However, the fact that this happened over billions of years cannot be ignored.

Due to this long period of time, which encompassed the process of the emergence of life on earth, it is impossible to reproduce it in its entirety and with fidelity within laboratories.

The obstacle of time has put scientists in front of a difficult scenario, because it may never be possible to know exactly how the first organisms that inhabited the planet were formed.

Despite this drawback, chemosynthetic theory has made it possible to draw a picture quite close to what may have been the genesis of life on Earth.

Themes of interest

Theories of the origin of life.

Creationism.

Panspermia.

Oparin-Haldane theory.

Theory of spontaneous generation.

References

1. Paula Andrea Giraldo. Chemosynthetic theory of the origin of life. Recovered from es.calameo.com.
2. Physicochemical theory of the origin of life. Recovered from academia.edu.