How did life arise on Earth? New scientific findings today shed a little more light on this, one of the greatest mysteries in our history. A team of Japanese researchers have found in the Ryugu asteroid one of the informational units that make up RNA, the molecule that contains the instructions for building and running living organisms.
The appearance of traces of uracil in Ryugu, the celestial body that travels through space some 300 million kilometers from our planet, opens the doors to new hypotheses about the beginning of our times and life beyond our planet. On Earth, uracil – one of the four genetic letters that RNA is made of – is an essential ingredient of life. So what does the discovery of this molecule in space imply?
In 2018, the Japanese Space Agency (JAXA) sent the Hayabusa2 spacecraft to the Ryugu asteroid with the aim of collecting samples from that space body and bringing them to Earth for analysis. In 2020 the first fragments of Ryugu arrived, and this Tuesday Nature Communication has reported on the first results.
In addition to uracil, scientists have also revealed the presence of small amounts of niacin, a component present in vitamin B3 and which is a key piece in the formation of more complex organic molecules, since it helps living beings to extract energy from nutrients and form and preserve DNA.
Following this finding, the team of astrobiologists led by Yasuhiro Oba suggests that the basic parts that make up life on earth could have been created in space, extraterrestrially, and reached Earth in carbon-rich meteorites. According to this theory, dubbed “panspermia”, the basic ingredients for life to arise are in space and only need to fall in a suitable place and time for life to be born. Thus, a great diversity of basic compounds and living beings could have been formed in space, but the conjunction of all the elements was only possible on Earth.
Another of the most interesting results of the research is that the samples taken from inside the asteroid contain more uracil than the surface ones. This confirms that the asteroids would be like “chests” that protect the material, intact, from the origins of the solar system.
“This is an exciting discovery, as it reveals that uracil (one of the RNA nucleobases) can be synthesized in space,” says Izaskun Jiménez-Serra, a CSIC scientist at the Center for Astrobiology in Madrid (CAB). As explained by the researcher at the Science Media Center (SMC), this compound could have reached Earth through the impact of meteorites between 4,100 and 3,800 million years ago and, from that moment on, it would have “triggered the first biochemical outbreaks that led to the origin of life on Earth.
This landmark study represents a milestone in space research, but as is often the case with this type of research, the answers lead to new questions. Even so, this and other studies will gradually clarify something more about the beginning of life on our planet.
