Primordial soup , or prebiotic soup also sometimes referred as prebiotic broth , is the hypothetical set of conditions present on the Earth around 4. It is a fundamental aspect to the heterotrophic theory of the origin of life , first proposed by Alexander Oparin in , and John Burdon Sanderson Haldane in The notion that living beings originated from inanimate materials comes from the Ancient Greeks—the theory known as spontaneous generation. Aristotle in the 4th century BCE gave a proper explanation, writing:.
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Primordial soup , or prebiotic soup also sometimes referred as prebiotic broth , is the hypothetical set of conditions present on the Earth around 4. It is a fundamental aspect to the heterotrophic theory of the origin of life , first proposed by Alexander Oparin in , and John Burdon Sanderson Haldane in The notion that living beings originated from inanimate materials comes from the Ancient Greeks—the theory known as spontaneous generation.
Aristotle in the 4th century BCE gave a proper explanation, writing:. So with animals, some spring from parent animals according to their kind, whilst others grow spontaneously and not from kindred stock; and of these instances of spontaneous generation some come from putrefying earth or vegetable matter, as is the case with a number of insects, while others are spontaneously generated in the inside of animals out of the secretions of their several organs .
Aristotle also states that it is not only that animals originate from other similar animals, but also that living things do arise and always have arisen from lifeless matter. His theory remained the dominant idea on origin of life outside that of deity as a causal agent from the ancient philosophers to the Renaissance thinkers in various forms.
Italian physician Francesco Redi demonstrated in that maggots developed from rotten meat only in a jar where flies could enter, but not in closed-lid jar. He concluded that: omne vivum ex vivo All life comes from life. The experiment of French chemist Louis Pasteur in is regarded as the death blow to spontaneous generation.
He experimentally showed that organisms microbes can not grow in a sterilised water, unless it is exposed to air. The experiment won him the Alhumbert Prize in from the French Academy of Sciences , and he concluded: Never will the doctrine of spontaneous generation recover from the mortal blow of this simple experiment.
Evolutionary biologists believed that a kind of spontaneous generation, but different from the simple Aristotelian doctrine, must have worked for the emergence of life. French biologist Jean-Baptiste de Lamarck had speculated that the first life form started from non-living materials. When English naturalist Charles Darwin introduced the theory of natural selection in his book On the Origin of Species in , his supporters, such as a German zoologist Ernst Haeckel , criticised him for not using his theory to explain the origin of life.
Haeckel wrote in "The chief defect of the Darwinian theory is that it throws no light on the origin of the primitive organism—probably a simple cell—from which all the others have descended. When Darwin assumes a special creative act for this first species, he is not consistent, and, I think, not quite sincere.
Although Darwin did not speak explicitly about the origin of life in On the Origin of Species , he did mention a " warm little pond " in a letter to Joseph Dalton Hooker dated February 1, . It is often said that all the conditions for the first production of a living being are now present, which could ever have been present. But if and oh what a big if we could conceive in some warm little pond with all sort of ammonia and phosphoric salts,—light, heat, electricity present, that a protein compound was chemically formed, ready to undergo still more complex changes, at the present such matter would be instantly devoured, or absorbed, which would not have been the case before living creatures were formed [ A coherent scientific argument was introduced by a Soviet biochemist Alexander Oparin in According to Oparin, in the primitive Earth's surface, carbon, hydrogen, water vapour, and ammonia reacted to form the first organic compounds.
Unbeknownst to Oparin, whose writing was circulated only in Russian, an English scientist John Burdon Sanderson Haldane independently arrived at similar conclusion in When ultra-violet light acts on a mixture of water, carbon dioxide, and ammonia, a vast variety of organic substances are made, including sugars and apparently some of the materials from which proteins are built up.
Today the theory is variously known as the Heterotrophic theory , Heterotrophic origin of life theory or the Oparin-Haldane hypothesis. The mixture of such compounds with water under the atmosphere of the primitive Earth is referred as the prebiotic soup. There, life originated and the first forms of life were able use the organic molecules to survive and reproduce. It is important to make the distinction between prebiotic and abiotic processes.
While an abiotic process refers to anything that occurs without the presence of life, a prebiotic process refers to something that happens in the atmospheric and chemical conditions that the primitive Earth had about 4.
This nucleus was surrounded by the lightest elements, i. In the presence of water vapour, carbides reacted with hydrogen to form hydrocarbons. Such hydrocarbons were the first organic molecules. These further combined with oxygen and ammonia to produce hydroxy- and amino-derivatives, such as carbohydrates and proteins.
These molecules accumulated on the ocean's surface, becoming gel-like substances and growing in size. They gave rise to primitive organisms cells , which he called coacervates. However, when he elaborated his theory in in a book by the same title, and translated into English in ,  he modified the chemical composition of the primordial environment as strictly reducing, consisting of methane, ammonia, free hydrogen and water vapour—excluding oxygen. In his work, impregnated by a Darwinian thought that involved a slow and gradual evolution from the simple to the complex, Oparin proposed a heterotrophic origin, result of a long process of chemical and pre-biological evolution, where the first forms of life should have been microorganisms dependent on the molecules and organic substances present in their external environment.
The idea of a heterotrophic origin was based, in part, on the universality of fermentative reactions, which, according to Oparin, should have first appeared in evolution due to its simplicity. This was opposed to the idea, widely accepted at that time, that the first organisms emerged endowed with an autotrophic metabolism, which included photosynthetic pigments, enzymes and the ability to synthesize organic compounds from CO 2 and H 2 O; for Oparin it was impossible to reconcile the original photosynthetic organisms with the ideas of Darwinian evolution.
From the detailed analysis of the geochemical and astronomical data known at that date, Oparin also proposed a primitive atmosphere devoid of O 2 and composed of CH 4 , NH 3 and H 2 O; under these conditions it was pointed out that the origin of life had been preceded by a period of abiotic synthesis and subsequent accumulation of various organic compounds in the seas of primitive Earth. There, according to Oparin, a particular type of colloid, the coacervates, were formed due to the conglomeration of organic molecules and other polymers with positive and negative charges.
Oparin suggested that the first living beings had been preceded by pre-cellular structures similar to those coacervates, whose gradual evolution gave rise to the appearance of the first organisms. Like the coacervates, several of Oparin's original ideas have been reformulated and replaced; this includes, for example, the reducing character of the atmosphere on primitive Earth, the coacervates as a pre-cellular model and the primitive nature of glycolysis. In the same way, we now understand that the gradual processes are not necessarily slow, and we even know, thanks to the fossil record, that the origin and early evolution of life occurred in short geologic time lapses.
However, the general approach of Oparin's theory had great implications for biology, since his work achieved the transformation of the study of the origin of life from a purely speculative field to a structured and broad research program. A point of convergence between these two branches of biology and that has been perfectly incorporated into the heterotrophic origin theory is found in the RNA world hypothesis.
Haldane independently postulated his primordial soup theory in in an eight-page article "The origin of life" in The Rationalist Annual. Ultraviolet rays from the Sun induced reactions on a mixture of water, carbon dioxide, and ammonia. Organic substances such as sugars and protein components amino acids were synthesised.
These molecules "accumulated till the primitive oceans reached the consistency of hot dilute soup. As to the priority over the theory, Haldane accepted that Oparin came first, saying, "I have very little doubt that Professor Oparin has the priority over me. One of the most important pieces of experimental support for the "soup" theory came in A graduate student, Stanley Miller , and his professor, Harold Urey , performed an experiment that demonstrated how organic molecules could have spontaneously formed from inorganic precursors, under conditions like those posited by the Oparin-Haldane Hypothesis.
The now-famous " Miller—Urey experiment " used a highly reduced mixture of gases— methane , ammonia and hydrogen —to form basic organic monomers , such as amino acids. The spontaneous formation of complex polymers from abiotically generated monomers under the conditions posited by the "soup" theory is not at all a straightforward process.
From Wikipedia, the free encyclopedia. Main article: Miller—Urey experiment. The History of Animals. Oxford: Clarendon Press. Retrieved Historical Encyclopedia of Natural and Mathematical Sciences 1st ed. Berlin: Springer. Bulletin of the History of Medicine. Journal of Applied Microbiology. Cold Spring Harbor Perspectives in Biology.
What is Life? On Earth and Beyond. Origins of Life and Evolution of Biospheres. Bantam Books. In Bernal, John Desmond ed. The Origin of Life. World natural history. Translated by Synge, Ann. London: World Pub. The origin of life. New York: MacMillan. The Rationalist Annual. William; Lazcano, Antonio Journal of Molecular Evolution.
Bibcode : JMolE.. Bibcode : Sci Bibcode : Natur. Origin of life. Common descent Earliest known life forms Last universal common ancestor Protocell Symbiogenesis. Evolutionary biology portal. Astrobiology Evolutionary biology Paleobiology. Categories : Evolutionarily significant biological phenomena Evolutionary biology Origin of life.
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Organic compounds were synthesized nonbiologically by ultraviolet light energy, which in the absence of an ozone shield would penetrate the upper layers of the ocean. Without free O 2 to oxidize them, these organic molecules would be stable, and would accumulate in a warm, dilute broth that has been nicknamed "Haldane soup. The first living organism would be little more than a few chemical reactions wrapped up in a film or membrane to keep them from being diluted and destroyed. These organelles would absorb chemicals, grow, divide, and obtain energy by fermenting the available organic molecules around them.
Structural Biochemistry/The Oparin-Haldane Hypothesis