Scientists have been long obfuscated by the mechanisms that allowed life to blossom. One of the great debates in the study of the origin of life, abiogenesis, is whether the building blocks of life arose spontaneously or were seeded here from elsewhere. Now, a group of researchers at the National Centre for Scientific Research in France (CNRS) have found that comets may have planted the first organic molecules on earth, which enabled life to burgeon.
When the solar system formed 4.6 billion years ago, ice grains floating around in space were exposed to sunlight, which triggered the formation of sugar molecules on their surface. These sugar molecules would have harbored ribose, a pivotal ingredient in RNA and in turn, the formation of life.
Although RNA and DNA are important to living organisms, the former is thought to be more primitive than the latter. In particular, RNA can both catalyze chemical reactions and store genetic information. The theory is that RNA preceded and gave rise to DNA, the central dogma of molecular biology.
How to cook up a comet in the lab
The researchers confirmed that this reaction with ice grains was possible after replicating the scenario in a lab. After millions of years, ice grains with ribose may have conglomerated into a comet, which crash landed into earth where other building blocks for life, like amino acids, were present, according to the study published in the journal Science.
CNRS researchers created an artificial comet in the lab through a mixture of ammonia, water and methanol. The mix was then placed in a vacuum chamber of minus 200 degrees Celsius. Afterwards, the sample was blasted with ultraviolet rays and warmed to room temperature to make it seem like a comet hurtling towards the sun. The researchers found that their artificial comet contained amino acids necessary for life.
Successfully obtaining ribose is a major step towards understanding the origin of RNA. As a report published by Science Daily notes:
“The genetic material of all living organisms on Earth, as well as of viruses, is made up of nucleic acids, DNA and RNA. RNA, which is considered more primitive, is thought to have been one of the first molecules characteristic of life to appear on Earth. Scientists have long wondered about the origin of these biological compounds.”
Unearthing life’s earliest origins
In fact, many amino acids and nitrogenous bases have been unearthed in both comets and artificial comets. According to an article written by Maddie Stone with Gizmodo, “The case that we’re all just highly organized lumps of space candy keeps getting better. For the first time, scientists have created ribose—the key sugar underlying RNA—in laboratory conditions simulating the cold, radiation-blasted vacuum of outer space.”
Scientists are in the dark about life’s earliest origins. Since the fossil record isn’t much help, scientists try to replicate earth’s earliest conditions in the lab. The recent study supports previous research that discovered organic molecules on a comet by the Philae Lander, which triumphantly landed on a comet back in 2014.
Dr. Cornelia Meinert of the University of Nice-Sophia Antipolis, who was involved in the study, concluded: “Our detection of ribose provides plausible insights into the chemical processes that could lead to formation of biologically relevant molecules in suitable planetary environments.” If this theory is correct, then the authors of the study may have stumbled upon how life originated, not just on Earth, but throughout the universe.