Top 10 theories of the origin of life

We explain the most influential explanations of the origin of life.

It is estimated that the planet Earth has existed for 4550 million years. Life as we know it seems to have arisen approximately one billion years later. But where exactly did it come from? This question has been asked by philosophers and scientists for many centuries and has given rise to various theories about its origins.

In Western culture, these theories have their basis either in Christianity or in science. In this sense, the proposals range from the will of a divine being to the evolution of our genetic material, passing through the interventions of cosmic material and the composition of inert matter. In this article we will review 10 of the main theories on the origin of life on Earth.

10 theories about the origin of life

As we have said, the theories on the origins of life on earth range from the proposals of Christianity to the most complex scientific hypotheses; largely developed by the physical, chemical and Biological sciences. The following is an overview of these proposals.

1. Creationism theory

The most widespread biblical account of the origins of life suggests that it occurred by the intervention and will of a divine being. In the book of genesis, within the Old Testament, it is explained that this being was dedicated to generate the different states and living beings as we know them. In the course of seven days, he created the sky and the earth, and then originated the light, the darkness, the seas, the vegetation, the sun and the moon, the animals, the man and the woman, and finally, he rested.

This is the the theory that has been most current in Western societies through the centuries, until progress in research inheriteduntil the progress in research inherited from the Scientific Revolution questioned it.

2. Theory of the genesis under the ice

One of the proposals about the origins of life on earth is that billions of years ago, the oceans were completely covered by a very thick layer of ice. Being such a thick layer, even hundreds of meters thick, it was possible that the organic compounds were very well protected from external agents, and from the sun itself, which before was much more powerful given the conditions of the planet earth.

Thus, the strong protection of the ice sheet could generate a safe interaction of microorganismsand eventually create life forms.

3. Electrical activity theory

Broadly speaking, this theory proposes that electrical currents can produce simple amino acids and sugars from various simple chemical compounds found in the atmosphere. In this sense, life would be originated as a consequence of the presence of lightning. the presence of lightning, which, upon contact which, on coming into contact with the elements of the Earth's atmosphere, may have been responsible for originating the first and most basic forms of life.

4. Panspermia

Panspermia proposes that life on earth began from rocks, meteorites and remnants of cosmic material that have impacted our planet since its first moments of existence. Such material is supposed to have been transported through cosmic dust, and kept on earth by the action of gravity. Panspermia proposes that the existence of this debris could have generated the organic and bacterial material necessary to generate life.. It was first proposed by the German biologist Hermann Ritcher in 1865.

5. Spontaneous generation

Spontaneous generation is one of the oldest and best known theories about the origins of life. Broadly speaking, it proposes that life is generated spontaneously or naturally from microorganisms present in inert matter. In its oldest forms, the theory of spontaneous generation considered that life is created because some inert materials can give rise to living organisms (e.g., manure to generate flies).

In this context, the experiment performed by the Italian physician Francesco Redi, who tried to prove that inert matter does not generate life, but attracts it, is classic. What he did was to leave a piece of meat uncovered, and another piece of meat inside a closed jar. He found that flies did not emerge from the meat, but from the eggs left by other flies when it was uncovered. when the meat was uncovered. Finally, it was Louis Pasteur who proved that microorganisms do not arise from inert matter but are in the air, and such matter only attracts them.

6. Theory of abiogenesis

Reformulating the theory of spontaneous generation, the theory of abiogenesis has emerged, which proposes that there is a natural process in inert matter from which life arises. For example, it is proposed that life on earth began when water vapor could finally condense, because this generated geochemical and astronomical processes that in turn originated the minimal genome. From this it follows that spontaneous generation could have been a real process, but millions of years ago (not in the present state of our planet).

Likewise, the theory of abiogenesis suggests that life was generated by different chemical reactions that gradually different chemical reactions that gradually allowed the evolution of the most primitive organisms..

7. Theory of submarine suckers

Hydrothermal vents, also known as hot springs or hydrothermal submarine vents, are found in the depth of the ocean. These are cracks and fumaroles that allow the passage of steam and hot water. These vents have very extensive ecosystems. According to this theory, the nutrient-rich oceanic environment, along with reactive gases, could have created the habitat necessary to generate the first life forms.

In other words, the origins of life as we know it could have taken place within the vents. may have taken place inside hydrothermal ventsThis question also takes up the proposals about what could have occurred under the ice sheets that previously covered the oceans.

8. RNA (and protein) theory

Ribonucleic acid is the compound currently considered crucial in the organization and expression of our genetic material. It works together with deoxyribonucleic acid, DNA, transferring and systematizing the vital information that the latter generates. It is a kind of messenger of DNA and has the ability to regulate itself in a more automatic way. The theory of the generation of life, which is explained by RNA, says that it occurred by a spontaneous outbreak of RNA on our planet..

In view of this, an important question has emerged: which came first: RNA or proteins? Some theories postulate that without the synthesis of the latter, RNA could not have emerged, much less spontaneously, since the most basic components of proteins are too complex.

9. Theory of genesis underneath the mud

There is also the proposal that life on earth evolved from the concentration of mud. This is because this concentration could serve as an area of condensation of chemical activity, which could eventually give rise to a kind of "breeding ground" of the components necessary to generate genetic material (DNA and RNA).

10. Metabolism theory

In contrast to the theories of RNA, the theories of metabolism say in very broad strokes that chemical elements and atmospheric nutrients simply continued to react over time, producing increasingly complex molecules. Thus, gradually, the first forms of life and later life as we know it came into being.

Bibliographical references:

• Marshall, M. (2016). The secret of how life on earth began. BBC. Retrieved July 10, 2018. Available at http://www.bbc.com/earth/story/20161026-the-secret-of-how-life-on-earth-began.
• Futurism (2015). Abiogenesis: 7 scientific theories for the origin of life… and one new one! Recuperado 10 de julio de 2018. Disponible en https://futurism.com/abiogenesis-7-scientific-theories-origin-life-one-new-one/.
• Daminelli, A. & Santa Cruz, D. (2007). Origins of life. Estudos Avançados 21(59): 263-285.