In 1953, the American Stannley Lloyd Miller built a device containing methane, ammonia, hydrogen and water vapor, according to the Oparin model, which simulated possible conditions on Earth primitive. This gaseous mixture was subjected to electrical discharges, as a way of simulating the lightning that should have occurred. With the presence of a condenser in the system, the product was cooled, accumulated and then heated. This last process caused the liquid to evaporate, continuing the cycle.
After a week of operation, there was an accumulation of brown organic substances in a certain region of the device, among which he found several amino acids.
Miller's research was a pioneer in the sense of raising questions about the possibility that the matter that was the precursor of life to have formed spontaneously, due to the set of conditions existing there. It is now known that the early Earth's atmosphere contained 80% carbon dioxide, 10% methane, 5% carbon monoxide and 5% nitrogen gas.
A few years later (1957), along the same lines, the American biochemist Sidney Fox heated a dry mixture of amino acids and found the presence of protein molecules, consisting of a few amino acids. The experiment showed that these could have joined through peptide bonds, in a synthesis by dehydration.
Melvin Calvin, another American scientist, carried out experiments, bombing the gases primitives with highly energetic radiations and obtained, among others, organic compounds of the type carbohydrate.
All these experiments demonstrated the possibility of the formation of organic compounds before the appearance of life on Earth. This favored the heterotrophic hypothesis, since the prior existence of organic matter is a basic requirement not only for feeding the first heterotrophs, but also for their own formation.
By Mariana Araguaia
Graduated in Biology
