Avalanche of Reactions at the Origin of Life
Mechanism of evolution of the primordial metabolism discovered
Volcanic-hydrothermal flow channels offer a chemically unique environment, which at first glance appears hostile to life. This environment is defined by cracks in the crust of the earth through which water flows. This water, laden with volcanic gases, contacts a diversity of minerals. It is precisely this extreme environment where the two mechanisms could have emerged that are at the root of all life: The multiplication of biomolecules (reproduction) and the emergence of new biomolecules on the basis of previously-formed biomolecules (evolution).
"This coupling between the catalyst and an organic reaction product is the first step", explains Wächtershäuser. "Life arises, if subsequently a whole cascade of further couplings takes place, and this primordial life leads eventually to the formation of genetic material and of the first cells".
The scientists simulated in their experiments the conditions of volcanic-hydrothermal flow channels and established an aqueous-organometallic system that produces a whole suite of different biomolecules, among them the amino acids glycin and alanin. Here the carbon source was provided by a cyano compound and the reducing agent by carbon monoxide. Nickel compounds turned out to be the most effective catalysts in these experiments. The scientists then added the products glycin and alanin to another system, generating two new biomolecules. The result: The two amino acids increased the productivity oft he second system by a factor of five.
The results of the scientists around Wächtershäuser and Eisenreich show that an origin and evolution of life in hot water of volcanic flow ducts is feasible. The results reveal advantages of the theory compared to other approaches. Within the flow ducts temperature, pressure and pH change along the flow path, and thereby a graded spectrum of conditions is offered that is appropriate for all stages of early evolution up to the formation of genetic material (RNA/DNA).
The most important property of the system is its autonomy: As opposed to the notion of a cool prebiotic broth, the first metabolism was not dependent on accidental events or an accumulation of essential components over thousands of years. As soon as the first domino stone is toppled, the others will follow automatically. The origin of life proceeds along definite trajectories, pre-established by the rules of chemistry – a chemically determined process giving rise to the tree of all forms of life.