Understanding the origins of life, and why (so far) only Earth is home to nearly infinite forms of life is perhaps one of the greatest mysteries of the universe.
To understand why and how life came to be, scientists spend a lifetime researching, experimenting and studying.
DNA is of great importance, but what if there was something more? What if before DNA, something else played a crucial role in the development of life?
We know that DNA is the backbone of life, and nearly all life on Earth depends on it.
However, in ancient Earth, this wasn’t the case. Scientists have discovered that in distant times, a primitive version of its lesser-known sister – RNA – was the focal point of evolution.
RNA, Ribonucleic acid, is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. It is a structure eerily similar to DNA, expect one of the four fundamental pieces, thymine swapped for uracil.
This ‘small’ change actually alters the shape and structure of the molecule. Long have scientists believed that this chemical was the cause of Earth’s first lifeforms appearing on the planet.
Now, researchers at Harvard have discovered that a slightly different–modified—version of RNA may have been essential for allowing life on Earth to come into existence.
According to researchers, a chemical called inosine was present in RNA in place of guanine, a change that allowed life to develop.
Scientists claim that this discovery provides the first known evidence of the ‘RNA World Hypothesis’ – a scientific theory which proposes that RNA was integral to primitive lifeforms on ancient Earth.
According to Jack Szostak, a professor at Harvard University, and lead author of the study Seohyun Kim, RNA may have used inosine as a ‘surrogate’, allowing life to blossom.
“Our study suggests that the earliest forms of life (with A, U, C, and I) may have arisen from a different set of nucleobases than those found in modern life (A, U, C, and G),” explained Kim.
“Lab attempts to craft A and G, purine-based nucleotides, produced too many undesired side products. Recently, however, researchers discovered a way to make versions of adenosine and inosine—8-oxo-adenosine and 8-oxo-inosine—from materials available on primeval Earth. So, Kim and his colleagues set out to investigate whether RNA constructed with these analogs could replicate efficiently.”
They encountered problems as the reaction produced too many undesirable side-products.
Inosine made it possible for RNA to replicate with higher speeds and lesser errors, something that is essential for reproduction.
“[It] turns out to exhibit reasonable rates and fidelities in RNA copying reactions. We propose that inosine could have served as a surrogate for guanosine in the early emergence of life,” explained researchers.
Eventually, armed with this knowledge, scientists could identify other planets that have the essential ingredients and determine whether we share this universe or are, indeed, alone.