Could the building blocks of life on Earth have come from space? All the key ingredients for life were brought to Earth by meteorites, claim scientists. Fundamental Research © CreativeColony, Shutterstock For several decades, the scientific community has been considering the theory that life on Earth was delivered here by a meteorite. Now, there’s mounting evidence published in the journal ‘Nature Communications’ that this idea isn’t so out of this world after all. Five types of chemical building blocks or nucleobases are needed to produce DNA and ribonucleic acid (RNA). Until now, only three nucleobases in meteorites found in DNA and RNA in life on Earth had been identified. The other two had not been found in meteorites. All five ingredients necessary for DNA Scientists at NASA and in Japan used new analysis methods that enabled them to identify the missing building blocks inside meteorites. They analysed the material of three meteorites. The first fell in the United States in 1950, the second in Australia in 1969 and the third in Canada in 2000. All three are rich in carbon, an element found in all living things. They are also made of rocky material believed to have formed early in the solar system’s history. The team of scientists identified the two missing nucleobases for the first time. Now, all five key building blocks of DNA and RNA in space rocks that fell to Earth have been found. “The detection of all primary DNA and RNA nucleobases in meteorites indicates that these molecules have been supplied to the early Earth before the onset of life,” lead author and astrochemist Yasuhiro Oba of Japan’s Hokkaido University told ‘Popular Science’. “In other words, we got information about the inventory of organic molecules related to DNA and RNA before any life arose on the Earth.” According to the research, the compounds may have been partially created by photochemical reactions in space. Later on, they were incorporated into asteroids as the solar system formed. Life being formed beyond Earth “There is still much to learn about the chemical steps that led to the origin of life on Earth - the first self-replicating system,” astrobiologist and study co-author Daniel Glavin of NASA’s Goddard Space Flight Center in Maryland, United States, told ‘Reuters’. “This research certainly adds to the list of chemical compounds that would have been present in the early Earth’s prebiotic (existing before the emergence of life) soup.” “The present results may not directly elucidate the origin of life on the Earth,” Prof. Oba added, “but I believe that they can improve our understanding of the inventory of organic molecules on the early Earth before the onset of life.” Long before a space rock slammed into Earth and drove the dinosaurs to extinction, other space rocks came crashing down containing the chemistry needed to make life possible. Whether or not you choose to believe this is where we came from, the research will help us to better understand how DNA defines our lives on this planet. Keywords DNA, meteorite, space, compound, nucleobase, ribonucleic acid, RNA, molecule
