Origin of life theory, definition: We analyze what the origin of life is and the various theories that tried to answer that question. Also, what science says.
What is the origin of life?
The question of the origin of life has accompanied human beings since the beginning of civilization itself, and is one of the great universal mysteries that science has endeavored to solve.
But it has not been easy to find an explanation for a phenomenon that precedes us as a species by many billions of years, and of which we have seen, therefore, only a very recent percentage. You must read about Atheism once.
Ancient civilizations, endowed with a deeply religious character, always attributed to their gods the creation of the cosmos, the Earth and life itself, through different cosmogonic myths. These mythological stories could have points in common, or differ substantially according to the culture that imagined them.
Such points of view were gradually discarded by empirical and scientific thought, which maintained the existence of some logical and verifiable explanation, which could be accessed through experimentation and theoretical knowledge.
The great advances in anatomy, chemistry, genetics and especially the studies of Louis Pasteur (1822-1895), Charles Darwin (1809-1882) and Alexandr Oparin (1894-1980) played a major role in understanding that, necessarily, all living beings come from another previous living being that engendered them.
Today, the science and technology we have have allowed us to seek a satisfactory explanation in the multiple biological evidence of the world, both the modern and observable with the naked eye, as well as the ancient evidence that makes up the fossil record.
Although we have a more or less complete scientific explanation, supported by abundant empirical evidence, there are still unanswered questions and issues that keep scientists in suspense.
Below, we will review the main theories on the origin of life that have emerged in the history of humanity. Maybe you should definitely read about Contemporary Age once.
The creationist theory
The first explanations that human beings proposed regarding the origin not only of life, but also of the universe, were based on their religious conception of the cosmos. According to this point of view, there were ancient deities, creators, maintainers and destroyers of the universe, responsible for the creation of everything that exists and especially of living beings, among which the human being occupied the place of the favorite son.
This approach is contained in its own way in all the great religious texts, such as the Bible, the Koran, the Talmud, the Popol-Vuh, etc. In them, one or more gods were responsible for creating humanity from inanimate elements, such as mud, corn or clay.
Contrary to what one might think, such a point of view was held until practically the Modern Age, by the great monotheistic religions and their respective churches, among which the Catholic Church always played a central role in the West.
According to Christian dogma, life on Earth was created by God over the seven days it took him to create the universe entirely by his own will. He also created human beings in the same way: Adam, made of clay in his image and likeness, and Eve, created from one of Adam’s ribs. God created their bodies and created their souls, and allowed them to reproduce in order to populate and work the Earth, making them lords over the rest of living beings.
Spontaneous generation
The theory of spontaneous generation emerged as a materialistic way of thinking, less guided by Christian religious orthodoxy, took hold in the West, after the collapse of the feudal world of the Middle Ages.
Its roots, however, can be found in various philosophers and naturalists of antiquity, such as Aristotle (384-322 BC), but its main proponents were thinkers such as René Descartes (1596-1650), Francis Bacon (1561-1626), Isaac Newton (1643-1727) and the Belgian naturalist Jean Baptista van Helmont (1580-1644).
According to this theory, life was constantly originating on Earth, spontaneously, that is, by itself, from waste substances and excretions, such as sweat, urine, excrement and decomposing organic matter.
Initially, this theory explained the appearance of flies, lice, scorpions, rats and other animals considered pests. Later, it was challenged by the fact that these animals reproduced and laid eggs.
Furthermore, from the first discoveries in evolutionary matters, the theory of spontaneous generation maintained that only microorganisms were generated spontaneously, and that the rest of life evolved from them.
Spontaneous generation was difficult to refute by science, since it was basically a theory that could be combined with creationism: if life appeared spontaneously, it could be said that it was the invisible hand of God that made it possible.
It was only with Pasteur’s experiments that it was possible to refute this theory. This French chemist demonstrated the existence of microorganisms in the air that contaminated substances and made them ferment. Thus, the impossibility of life being generated magically was understood.
The panspermia theory
This is the theory that proposes that life has an extraterrestrial origin. It was an explanation that emerged at the end of the 19th century, and that attempted to respond to the difficulties in explaining the chemical transition between inanimate and living matter (what creationism attributed to the “divine breath” that breathed life).
To do so, this theory states that organic matter would have arrived on the planet in a comet, meteorite or some other type of space transport, whether accidental (natural panspermia) or voluntary (directed panspermia).
This position has been highly criticized because it does not really answer the question about the origin of life, but rather shifts the question to unknown space.
Furthermore, it does not answer how the original microorganisms were able to survive the cruel conditions of outer space, although it is true that some bacterial species could be “revived” in ideal conditions, after having been subjected to environmental rigors.
This theory was supported by the German biologist Hermann Richter (1808-1876), the British astronomer Fred Hoyle (1915-2001) and especially the Swedish scientist Svante August Arrhenius (1859-1927), who popularized it by winning the Nobel Prize in Chemistry in 1903.
Oparin’s theory
Based on the work of Alexandr Oparin and the understanding of DNA and the mechanisms of genetic inheritance, theories on the origin of life are guided by a scientific framework, especially biochemical and geochemical.
Scientific theories propose life as the result of a complex and unpredictable series of inorganic chemical reactions that allowed the gradual emergence of the first and primitive forms of cellular life.
In his Origin of Life on Earth, Oparin explained that the planet’s primitive seas were a warm soup of organic and inorganic substances, which were linked together to form increasingly complex and voluminous compounds.
This eventually led to the appearance of coacervates: bubbles of primitive substances that allowed the passage of desired substances through their membrane and kept the undesired ones outside, in a sort of proto-cell.
Despite their obvious importance for the creation of a later scientific model, Oparin’s theories, based on Darwin’s theory of evolution and natural selection, failed to explain the mechanisms by which the transition between organic but inanimate forms of compounds and the first forms of life as such occurred.
In later years, various scientific hypotheses were developed in this regard:
- RNA World Hypothesis: According to this position, the creation of genes was the first step towards life, because it allows the complexity achieved to be transmitted to future generations.
- Iron-sulfur World Hypothesis: It assumes that this first step is the creation of a metabolism to systematize the absorption of energetic substances.
