A new discovery may explain the origin of life on Earth
Scientists from Scripps Research discovered a new set of chemical reactions that produce the building blocks of life with materials believed to be common in the primordial soup of early Earth, a press statement reveals.
The new discovery brings us a step closer to understanding how life flourished in the ancient past. It adds a new, strong hypothesis for the origin of life on Earth, detailing the materials and reactions that may have taken place long ago.
Investigating the origin of life
The very first lifeforms on Earth are thought to have originated in the primordial soup — a nutrient-filled mixture — billions of years ago. The reactions required for the building blocks of life are believed to have occurred thanks, in part, to energy from hydrothermal vents.
The exact reactions that took place during that period are largely unknown and they remain a great scientific mystery. Now, the Scripps scientists developed their own version of the primordial soup based on materials that were thought to be abundant in the early stages of life on Earth. They discovered a new set of chemical reactions using relatively simple ingredients that could have led to the first life on Earth.
The reactions were carried out with a mix of cyanide, ammonia, carbon dioxide, and alpha-keto acids. When the scientists mixed these materials, they started seeing their mixture produce more amino acids — which are a crucial component of the molecules required for life.
“We were expecting it to be quite difficult to figure this out, and it turned out to be even simpler than we had imagined,” said Ramanarayanan Krishnamurthy, lead author on the study. “If you mix only the keto acid, cyanide and ammonia, it just sits there. As soon as you add carbon dioxide, even trace amounts, the reaction picks up speed.”
The simplest is the preferred hypothesis
In a new paper, published in Nature Chemistry, the scientists describe the role played by each of the materials in their mixture. Alpha-keto acids are used by living cells today to make amino acids. Ammonia provides nitrogen, which is required for the conversion process. The cyanide enables the conversion, while the carbon dioxide speeds up the whole process.
The researchers also explain that their mixture essentially mimics the way amino acids are formed in living cells. The main difference is that the cyanide replaces the enzymes in living cells — cyanide was thought to be present in the primordial soup, but enzymes would not have existed at that time. The scientists believe that, as their process is simpler than other hypotheses, it is more likely to have occurred during the earliest stages of life formation on our planet.
“What we want to do next is continue probing what kind of chemistry can emerge from this mixture,” said Krishnamurthy. “Can amino acids start forming small proteins? Could one of those proteins come back and begin to act as an enzyme to make more of these amino acids?” The scientists will continue to investigate the chemical reactions that occur in their mixture to better understand the processes that could have been responsible for life on Earth.