(CN) – Heat in the ocean, which was nearly boiling 4 billion years ago, may have acted as the force that created the biomolecules needed for life on Earth, scientists said in a study published Wednesday.
There are two widely held theories as to how life originated, according to the study released in the journal ACS Central Science. One posits that life on Earth originated from self-replicating molecules of ribonucleic acid, or RNA. The other is called the “metabolism-first” principle.
“The metabolism-first principle argues, on the other hand, that simple metal catalysts were present in water in early Earth and aided in creating a soup of organic building blocks that subsequently formed the biomolecules necessary for life,” the scientists, from CSIR-National Chemical Laboratory and the Academy of Scientific and Innovative Research, both in India, write in the study.
“Every large molecule in our body, especially the important molecule RNA, is made up of building blocks. You can think of them as different bricks that make up a wall,” said co-author Kumar Vanka in an interview. “It is these building blocks that we refer to as ‘life’s precursors.’”
The new computational study shows that interaction between two molecules – hydrogen cyanide and water – would have been “sufficient to give rise to most of the important precursors to RNA and proteins in prebiotic times.”
Long before human life arose, hydrogen cyanide (HCN) was present in Earth’s atmosphere. The chemical compound would have condensed in the ocean, where it could have combined with water to create amino acids – the building blocks of proteins.
The researchers used the ab nitio nanoreactor, a recently developed computational chemistry tool, to show how this scenario might have played out. They mixed HCN and H2O to form several other molecules.
“HCN and H20 could have been the Adam and Eve of chemical evolution,” the researchers write in the study.
The study further suggests that this same process could have happened in ancient seas without the help of much outside energy, because the water was so hot.
“We found that contrary to what is accepted and believed in scientific circles, heat was more significant in making chemical reactions happen than light, in early Earth,” said Vanka in an interview.
In the famous 1953 Urey-Miller experiments, which showed that life-creating molecules could have formed in the reducing atmosphere of the early Earth and then dissolved in the oceans, scientists sent electrical sparks through a container filled with water, methane, ammonia and hydrogen. The four chemicals, which were abundantly present in the atmosphere of early Earth, formed HCN and other chemicals that further reacted to make amino acids.
But it was unclear how the chemicals would have been ignited back then. Earth’s atmosphere was hazy 4 billion years ago, and it would have been hard for something like lightning to act as the spark.
The nanoreactor was crucial for the scientists’ work, providing them with a new way to set up reactions. By not controlling the outcome of the molecular collisions to come, researchers could discover new reactions and watch how they played out.
Tamal Das and Siddharth Ghule joined Vanka on the research.