Building blocks of life in Milky Way
The building blocks of life have been found floating near the centre of the Milky Way in a discovery that raises the chance that life could have evolved on other planets in the galaxy.
Organic molecules, known as nitriles, are abundant in interstellar clouds, scientists have discovered, supporting the theory that similar life-sparking particles hitchhiked a ride to Earth.
The theory is known as the ‘‘RNA World’’ theory, which proposes that the ingredients for life arrived on meteorites and comets during a period of heavy bombardment roughly four billion years ago.
According to the scenario, life on Earth was originally based on the messenger molecule RNA (Ribonucleic acid), with DNA evolving later.
Nitriles can help to form RNA and a team of researchers have found several types floating in a reservoir near the centre of the Milky Way.
Dr Victor Rivilla, a researcher at the Centre for Astrobiology of the Spanish National Research Council (CSIC) said: ‘‘Here we show that the chemistry that takes place in the interstellar medium is able to efficiently form multiple nitriles, which are key molecular precursors of the ’RNA World’ scenario.’’
Life on Earth appeared around 3.8 billion years ago, approximately 700 million years after the planet first formed. But exactly how it got going is still a mystery.
Scientists have been hunting for regions of the galaxy where complex molecules might exist, and focussed on a super-cold molecular cloud at the centre of the Milky Way.
Using two telescopes based in Spain the team measured light bouncing back from the region to determine the chemical composition of its particles.
They detected three definite nitriles and two possible compounds.
Writing in the journal Frontiers in Astronomy and Space Sciences, the authors said the discovery not only offered more evidence in support of the ‘‘RNA world’’ theory, but raised the prospect of life evolving ‘‘in other places in the Galaxy under favourable Earth-like planetary environments’’.
Now the team is looking for the other particles, such as basic fats, that are needed to turn nitriles into RNA.
Second author Dr Izaskun Jime´nez-Serra, a researcher at CSIC added: ‘‘We have detected so far several simple precursors of the building blocks of RNA. But there are still key missing molecules that are hard to detect.
‘‘For example, we know that the origin of life on Earth probably also required other molecules such as lipids, responsible for the formation of the first cells.
‘‘Therefore we should also focus on understanding how lipids could be formed from simpler precursors available in the interstellar medium.’’