researchers studying meteorites have found that they contain several of the components needed to make DNA
on Earth. The discovery provides support for the idea that the building blocks for DNA were likely created in space, and carried to Earth on objects, like meteorites, that crashed into the planet's surface. According to the theory, the ready-made DNA parts could have then assembled under Earth's early conditions to create the first DNA.
The researchers, from NASA's Goddard Space Flight Center
, found adenine and guanine -- two of the nucleobases needed to make DNA (the other two are thymine and cytosine, which were not found) -- on meteorite samples. Additionally, the samples showed the presence of three molecules that are similar to nucleobases, but do not have a biological role on Earth: Purine, 2.6-diaminopurine, and 6.8-diaminopurine. Hypoxanthine and xanthine, compounds used in biological processes, but not DNA, were also found. What is particularly significant about the new research is that the scientists were able to confirm that the biological parts were created in space and carried to Earth.