Origin of life remains a mystery

The origin of life on Earth remains one of the greatest scientific mysteries. How did the first molecules form and organize themselves to give rise to living cells? A widely accepted theory relies on the crucial role of nucleic acids, such as DNA and RNA, in this process. These molecules are indeed capable of storing genetic information and replicating, which allows evolution and the biological complexity observed today. However, the question of how these nucleic acids managed to replicate under the hostile conditions of early Earth remains unresolved.

Role of nucleic acids in life

Nucleic acids, mainly DNA and RNA, play an essential role in all living organisms. They contain the instructions necessary for the production of proteins, the basic elements of cells. For life to appear and evolve, these molecules must be able to copy themselves, a process called replication. This allows organisms to grow, reproduce, and adapt to their environment. The replication of these molecules allows adaptation by facilitating the emergence of mutations and genetic variations.

Challenges of early Earth conditions

On early Earth, where conditions were much more extreme than today, the replication of nucleic acids was probably one of the first mechanisms to be established to allow the emergence of life. However, this process is not so simple. For a DNA or RNA molecule to replicate, it must first split into two strands. However, this separation is complicated by environmental conditions, such as salt concentration or temperature, which play a crucial role in the stability of the molecules. The question that arises is therefore: how could the first DNA or RNA molecules have naturally replicated in such an unstable environment?

New study proposes natural replication scenario

Within the framework of a new study, researchers from the Ludwig-Maximilians University of Munich have imagined a natural scenario in which this separation could occur without destroying the molecules. According to the researchers, the natural conditions in the rock pores of early Earth could have allowed the replication of nucleic acids. Imagine small cavities present in volcanic rocks where water and gas can interact in closed environments. On volcanic islands, these conditions were once common, offering dry and wet environments conducive to the formation of complex molecules.

Laboratory recreation of early Earth conditions

To test this theory, the researchers recreated this environment in the laboratory. They built a model of a rock pore where a flow of water rose while evaporating at a point of contact with a flow of gas. At this interface between the gas and water, they observed an accumulation of DNA molecules. In just five minutes, the concentration of DNA had tripled and after one hour, it was thirty times higher. However, this concentration was not sufficient. The DNA strands also needed to be able to separate for replication to continue.

Natural conditions enable DNA replication

Using a technique called FRET spectroscopy, which allows the measurement of the distance between two DNA strands, the researchers then found that the dynamics of the gas and water flow induced changes in salt concentration, promoting the separation of the strands. In other words, without having to change the temperature, this natural environment reproduced the conditions necessary for DNA replication. These results are fascinating, as they show that a simple geological environment, which was probably abundant on early Earth, could have allowed the replication of the first nucleic acid molecules without requiring extreme temperatures. This expands the possibilities for understanding how life could have emerged not only on Earth, but also on other planets that could offer similar conditions.