In a groundbreaking discovery, scientists have found that three meteorites contain the chemical building elements of DNA and its companion RNA. This is not the first time that building components have been discovered in meteorites, but this is the first time that the entirety of the collection has been found.
The study, led by a team of researchers, supports the idea that four billion years ago, a bombardment of meteorites may have provided the chemical elements needed to kick-start the formation of the first life on Earth. However, not everyone is convinced that these newly discovered DNA components are of extraterrestrial origin.
According to Michael Callahan, an analytical chemist and astrobiologist at Boise State University who was not involved in the study, some of the building blocks may have ended up in meteorites after they landed on Earth. He states that “additional studies are needed” to rule out this possibility.
Assuming that all of the compounds did originate in space, one subset of building blocks, a class of compounds known as pyrimidines, appeared in “extremely low concentrations” in the meteorites, according to Callahan. This hints that the world’s first genetic molecules may not have emerged due to an influx of DNA components from space, but rather as a result of geochemical processes unfolding on early Earth.
Despite the exciting discovery, it is still uncertain what concentration of DNA building blocks meteorites would have needed to contain to aid in the emergence of life on Earth, according to Jim Cleaves, a geochemist and president of the International Society for the Study of the Origin of Life who was not involved in the study. Further research is needed to fully understand the implications of this discovery.
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