Recipe for success of the primitive or prebiotic soup, you need a wide variety of chemical elements such as carbon (C), hydrogen (H2), potassium (K), ammonia (NH3), nitrogen (N2), magnesium (Mg) and of course water (H2O).
These elements seem essential to the formation of the primordial soup that gave birth to organic life on Earth.
The chemical elements can be easily manipulated, they love to assemble and try all kinds of chemical combinations. When the conditions of temperature and pressure are favorable, as on Earth there are 4.4 billion years, these elements organize themselves without any help or any external intervention, they simply organize themselves by electromagnetic affinity (binding chemical between atoms).
In the primordial Earth's atmosphere, a magical assembly based on carbon-water couple will prove to be the easiest to support organic molecules and later, much later, the life. It is possible to make this recipe in laboratory, many teams of researchers have shown.
In 1953, an American biologist Stanley Miller (1930-2007) conducted at the University of Chicago's famous experiment, called the Miller-Urey experience. This experiment consists in recreating in the laboratory, in vitro, the conditions of the primordial soup. To conduct this experiment must only of chemical elements, water and electrical lightning.
By standing a few days this culinary mixture, some primitive amino acids, rush to the bottom of the tank.
Amino acids are the major elements in the construction of life as we know it. These are the basic building blocks of protein that will lead to the formation of long macromolecular chains, and the first living bricks. Harold Urey was convinced that existed on the early Earth atmosphere containing the chemical elements needed to structures of living things.
In 1953 to check the relevance of this theory, Stanley Miller imagine a physicochemical experience. The apparatus is filled with an atmosphere of methane, ammonia and hydrogen.
A balloon filled with water simulates a primitive ocean (the water is heated by a resistance, which contributes to enrich the water vapor atmosphere). Two electrodes, which are used to produce lightning, provide energy to the system.
The primordial soup is thus performed in a liquid and warm environment in which prolonged accumulation (millions of years) of inert organic molecules will move from the inanimate to the animate. Thus, the inert organic matter will produce a new material, one that can grow and reproduce, i.e. living matter.
Of course recipe Stanley Miller has none chance to be that nature has followed to start the process of life.
The primordial atmosphere was not that of the simulation Miller, the primordial elements were not the same as those of Miller and the flashes of the primitive Earth did not match the electric arcs Miller. Besides, the critics of the time, which amounted to the conditions of the experiment are completely justified.
But the important thing is not in the reconstitution of the primordial soup. In 1953, that experience shows, it is the ease with which the elements to be assembled together by affinity or simply because they are partisans of least resistance.
Today, many models that can look like prebiotic conditions are created in the laboratory and scientists can produce organic molecules (amino acids, carbohydrates, lipids, proteins, nucleic acids, sugars,...).
| || |
Image: The Stanley Miller experiment of 1953.NB: the synthesis of organic molecules appears to be a very common phenomenon in the space. In the interstellar void, scientists have identified some 120 organic molecules containing between 2 to 13 carbon atoms. Many extraterrestrial bodies, comets and meteorites also contain a multitude of more or less complex organic molecules.
The apparatus is filled with an atmosphere of methane, ammonia and hydrogen. A balloon filled with water simulates a primitive ocean (the water is heated by a resistance, which contributes to enrich the water vapor atmosphere). Two electrodes, which are used to produce lightning, provide energy to the system.
After a week of functioning, various organic compounds including amino acids precipitate at the bottom of balloon.