Stop looking for alien life. It's right here, on Earth. You are one of them. Me too. We all are. At last, scientists have discovered evidence that supports the theory that part of our DNA actually comes from deep space.
People have been discovering components of DNA in meteorites since the 1960's, but researchers were unsure whether they were really created in space or if instead they came from contamination by terrestrial life. For the first time, we have three lines of evidence that together give us confidence these DNA building blocks actually were created in space.
Those are the words of Dr Michael Callahan, from NASA's Goddard Space Flight Center, Greenbelt, Maryland. He is the lead author of the research that is being published in Proceedings of the National Academy of Sciences of the United States of America.
The team found adenine and guanine in samples extracted from from twelve carbon-rich meteorite. These are two of the nucleobases of Deoxyribonucleic acid. The other two are cytosine and thymine. Together, the four carry the encoding that makes possible life on Earth — and possibly other places around the Universe.
Callahan and his team ruled out any potential terrestrial contamination, demonstrating that these nucleobases were produced in a chemical, non-biological reaction: ""In the lab, an identical suite of nucleobases and nucleobase analogs were generated in non-biological chemical reactions containing hydrogen cyanide, ammonia, and water. This provides a plausible mechanism for their synthesis in the asteroid parent bodies, and supports the notion that they are extraterrestrial." They also discovered that none of the nucleobase analogs found in the heart of these meteorites were present in the meteorite environment.
According to the research, the discovery "gives support to the theory that a 'kit' of ready-made parts created in space and delivered to Earth by meteorite and comet impacts assisted the origin of life." The obvious implication of this discovery is that, if life blocks are spread through the universe through comets and asteroids that impact on planets, the possibilities of life that uses the same blocks on other planets is a very real one. [NASA]