A new analysis of carbon meteorites suggests that they likely carried some of the building blocks needed for DNA to the Earth, according to a NASA-funded study published on Monday.


The research in the Proceedings of the National Academy of Sciences adds weight to the long-debated theory that at least some of the materials needed to make early life forms came to our planet via meteorites.

Although building blocks of DNA in meteorites were found in the 1960s, scientists have been unclear as to whether they originate from space or contamination by terrestrial life.

Researchers at the Goddard Astrobiology Analytical Laboratory funded by NASA, found three lines of evidence that confidently support the idea that life on Earth has its origins in outer space.

According to NASA, Goddard team collected the powdered samples of 12 carbon-rich meteorites, nine of which were recovered from Antarctica

In the course of a scientific examination to determine the chemical structure of compounds, the team found adenine and guanine, the building blocks of DNA, which are also referred to as nucleobases.

Moreover, in two of the meteorites, the team discovered for the first time trace amounts of three molecules related to nucleobases: purine, 2,6-diaminopurine, and 6,8-diaminopurine.

While the latter two molecules are almost never used in biology, such nucleobase-related molecules, called nucleobase analogs prove the compounds in the meteorites come from space instead of terrestrial contamination.

“You would not expect to see these nucelo base analogs if contamination from terrestrial life was the source, because they are not used in biology,” said Dr. Michael Callahan of NASA’s Goddard.

Follow-up research on an eight-kilogram sample of ice from Antarctica involving the same methods used on the meteorites, provided the second piece of evidence.

None of the nucleobase analogs were detected in the ice sample, further ruling out possibility of terrestrial contamination as an origin of life.

Lastly, the Goddard team found that the above-mentioned molecules were produced in a completely non-biological reaction, confirming by generating an identical suite of nucleobases and nucleobase analogs artificially, in the lab.

NASA’s findings have far-reaching implications as it is highly likely that DNA compositions of early life on Earth originate from outer space.

By Jung Eun-jung and news reports
(kristin2j@gmail.com)
Intern reporter
Edited by Rob York