Scientists have confirmed that DNA found in meteorites includes all five nucleobases essential for life, strengthening evidence that the chemical building blocks of biology formed in space long before Earth became habitable.
The discovery lends credence to theories that early Earth may have received critical organic compounds from asteroids and comets during periods of intense bombardment over 4 billion years ago. However, researchers emphasise that this does not imply that life, or humans, originated in space.
🚨Scientists have now found all of the DNA and RNA bases in meteoritesThis suggests humans didn’t originate on Earth — we came from space.pic.twitter.com/vdwE0wVhjd
In peer-reviewed studies published in Nature Communications and the Proceedings of the National Academy of Sciences,scientists confirmed the presence of adenine, guanine, cytosine, thymine, and uracil in carbon-rich meteorites. Earlier research had identified some of these nucleobases, but more recent analysis completed the full set, which forms the core components of DNA and RNA.
Advanced mass spectrometry was employed by researchers to analyse samples from the Murchison meteorite, which fell in Australia in 1969, in order to exclude terrestrial contamination through isotopic testing. They emphasise that no living organisms or complete DNA strands were discovered; only the molecular building blocks that are necessary for life were identified.
One of the main challenges in analysing DNA found in meteorites is contamination.Once meteorites land on Earth, they can absorb biological material from soil, water or even human handling, raising concerns that detected molecules may not be truly extraterrestrial.
To address this, researchers examined isotopic ratios within the nucleobases, as space-formed organic molecules typically contain higher levels of carbon-13 than those produced by life on Earth. Independent laboratories replicated the results using ultra-clean extraction methods, strengthening confidence that the molecules originated in space rather than from modern biological sources.
The early Earth experienced what scientists call the Late Heavy Bombardment, a period marked by frequent and intense asteroid impacts. Many researchers believe these collisions delivered water and organic compounds to the young planet, potentially shaping the conditions necessary for life to emerge.
Chemical reactions that ultimately resulted in the production of self-replicating molecules may have been facilitated by the presence of complex nucleobases in meteorites during that period. This indicates that prebiotic chemistry is widespread, as organic compounds have been detected in interstellar clouds and on comets, according to NASA's Astrobiology Programme. However, this does not substantiate the panspermia hypothesis or confirm extraterrestrial life in meteorites.
The research has triggered widespread discussion online, with some users interpreting the findings as evidence that life did not originate solely on Earth. Astrobiologists warn that the detection of nucleobases in meteorites does not prove the existence of living systems, but rather serves as chemical precursors.
Source: International Business Times UK
