Key Takeaways
- All five bases of DNA and RNA—adenine, guanine, cytosine, thymine, and uracil—have now been detected in meteorites.
- A unique “cold-brew” extraction method revealed these bases in meteorites without damaging delicate compounds.
- The findings support the idea that life’s building blocks might have arrived from space.
- Research indicates certain compounds were only present in meteorites, not in surrounding soil, hinting at an extraterrestrial origin.
- Further analysis of pristine asteroid samples from Ryugu and Bennu could confirm these findings.
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Meteorites hold all five DNA and RNA bases, hinting that life’s ingredients may come from space!
Meteorites Contain All DNA and RNA Bases, Hinting at Space Origins for Life
A recent study published in Nature Communications reveals that meteorites contain the five nucleobases essential for life’s genetic code, suggesting a possible extraterrestrial origin for some of life’s building blocks. Scientists, including astrochemist Daniel Glavin from NASA’s Goddard Space Flight Center and geochemist Yasuhiro Oba from Hokkaido University, discovered adenine, guanine, cytosine, thymine, and uracil in meteorites that landed in various locations around the world. These nucleobases combine with sugars and phosphates to create DNA and RNA, the molecules responsible for storing genetic information in all life on Earth.
Astrochemists have detected organic compounds in meteorites since the 1960s, but this is the first time that all five bases necessary for DNA and RNA have been found. Using a mild extraction method that involves cold water, researchers examined meteorite samples without damaging the delicate compounds. This technique allowed scientists to capture even fragile molecules, marking a significant improvement over previous studies that used harsher acids to extract compounds. According to Oba, this “cold-brew” extraction approach preserved the integrity of the nucleobases, enabling scientists to detect them in meteorites.
The Role of Space in Life’s Origins
Samples from meteorites that fell in Australia, Kentucky, and British Columbia revealed various compounds related to life, including the five nucleobases, some of their chemical isomers, and several amino acids. The researchers conducted comparisons between the chemical abundances of these compounds in meteorites and soil samples taken from the same sites. For some compounds, such as adenine and guanine, concentrations were higher in meteorites than in soil, indicating an extraterrestrial origin. However, cytosine and uracil concentrations were found to be higher in soil, suggesting possible earthly contamination.
Michael Callahan, a cosmochemist from Boise State University, expressed cautious optimism but pointed out that contamination could still play a role. Callahan noted that, while the researchers did find these compounds, additional evidence would solidify the extraterrestrial origin hypothesis. Glavin, however, believes that the detection of nucleobase isomers solely in meteorites, and not in soil, suggests the compounds came from space. He argues that contamination would likely result in isomers appearing in both the meteorite and soil samples.
To further investigate, scientists have turned to fresh asteroid samples. Oba and his team are analyzing material from the surface of asteroid Ryugu, returned by Japan’s Hayabusa2 mission in 2020. In 2023, NASA’s OSIRIS-REx mission is also expected to return samples from asteroid Bennu. According to Glavin, these pristine samples could clarify whether compounds like nucleobases genuinely originate from space, strengthening the hypothesis that meteoritic delivery may have played a role in seeding life on Earth.
These new findings add evidence to the theory that key ingredients for life may have arrived on Earth from space, potentially sparking life in an “interstellar soup.” As scientists continue to study both existing and newly collected samples, further insights may reveal the true origins of life’s essential components.
