Researchers at the Scripps Research Institute (TSRI) have discovered that the chemical reactions of elements present on Earth four billion years ago could have triggered the formation of life on the planet.
The research published in the journal Nature Communications said that life could have been formed by chemical reactions found on the planet during that period.
Ramanarayanan Krishnamurthy, associate professor of chemistry at TSRI and lead author of the study said: "This was a black box for us, but if we focus on chemistry, questions about the origins of life become less discouraging."
Researchers from the National Science Foundation, Center for Chemical Evolution of NASA (National Aeronautics and Space Administration) who joined the research at TSRI, studied the citric acid cycle, the key chemical reaction in all organisms.
It is believed that all aerobic organisms use the citric acid cycle to release energy stored in c ells. The researchers also say that the same organic cycle had been present in the reactions during the first life's formation period.
The TSRI research, however, found that the biological molecules used in the cycle are fragile and the chemical reactions would not have started in the first billion years of Earth since the chemicals did not exist during the period.
The researchers also studied the two nonbiological cycles called the HKG cycle and the malonate cycle, which could have been transformed into crude versions of the citric acid cycle Cycles such as a-keto acids and b-keto acid follow the same fundamental chemical reactions that are similar to the citric acid cycle. New reactions such as the Aldol additions brought new source molecules and elements such as beta and oxidative decarboxylations, which release carbon dioxide (CO2) in the cycles.
The researchers found that these reactions could result in the formation of amino acids along with CO2 as their end products. The formation of biological molecules such as enzymes could have replaced non-biological molecules, resulting in more elaborate and efficient systems.
Krishnamurthy said: "Chemistry may have stayed the same over time, it was simply the nature of the molecules that changed, the molecules evolved to be more complicated over time according to what biology needs."
Researchers from the University of California, Los Angeles (UCLA) and the University of Wisconsin-Madison previously confirmed that the 3.5-billion-year-old fossil discovered in 1982 in western Australia contains evidence of the oldest life forms in the earth. The carbon isotopes of the ancient fossil had been studied to find the trace of the oldest forms of life. It is believed that these primitive unicellular organisms existed during the time when the Earth had no oxygen in its atmosphere.
Scientists also believe that the life-forming elements had been brought to Earth by falling asteroids during the early phases of the formation of the planet. It is believed that life was formed in ponds or seabeds that were prone to tectonic activities.