More that 3,5 billion years have passed since life appeared on Earth, but scientists still argue about it. The point is that life has turned from a molecule to bacteria per 0,5-1 billion years, and this period is too short for such a serious event. Instead of enjoying life, the researchers are intensely thinking about how that may have happened. One of the popular hypotheses is that some life seeds had arrived to Earth from space. But what kind of seeds may have come here from space and how did they appear there?
 

E.A. Kuzicheva and N.B. Gontareva, research fellows of RAS Cytology Institute (Saint Petersburg) showed that abiogenic synthesis of compounds, that are complex enough – monomer units of nucleic acids – can proceed in outer space on the surface of comets, asteroids, meteorites or cosmic particles. These monomers had hit the Earth and shortened the evolution time significantly. The scientists find various organic molecules (amino acids, sugars, etc) and different components necessary for their synthesis on the surface of cosmic bodies. These organics are evidently synthesized there, but the researchers can’t be sure until they prove it. Saint Petersburg scientists have reproduced 5'-AMP (a DNA block, 5'-adenosine monophosphate) synthesis under conditions close to those in outer space. In order to synthesize APM, one should mix adenosine and inorganic phosphate. On our planet this reaction takes place in a solution, but there are no solutions in outer space. That is why the scientists have air-dried the components and got a film. Synthesis needs energy. The main outer space source of energy for all times is ultraviolet radiation of the Sun with different wavelengths. That’s why the films were exposed to heavy UV radiation. The synthesis was naturally performed in vacuum. And as a model of comet, asteroid, planetary or cosmic particles the scientists have used moon soil from Sea of Wealth brought to Earth by “Luna-16” automatic station. The soil appeared to be dark gray basalt dust with particles smaller than 0,2 mm.
 

After 7-9 hour exposure of dry films to UV radiation, the scientists found various compounds, but the most common was 5'-AMP – one of DNA and RNA monomer units. Radiation energy not only promotes synthesis, it also decomposes original and synthesized compounds. Moreover, the more intense the radiation is, the faster is the decomposition. That’s where moon soil helped. It turned out, that small amounts of moon soil prevent organic matter from decomposition - 5'-AMP output has increased 2,7 fold.
 

The researchers concluded that organic compound synthesis could take place on the surface of cosmic bodies under outer space conditions during first stages of the Solar System genesis. And at the same time the chemical evolution had begun – complex molecules had started to form and to sort. When our planet formed, chemical evolution could have been very close to the stage, where biological evolution starts. In other words, life on Earth hasn’t started with elementary organic molecules’ synthesis; it has started with the stage of forming polymers, or even from the later stage. The scientists hope that such hypotheses will help us to get a little bit closer to the “fast life appearance on the Earth, that has just formed” paradox solution.