An international team of scientists has directly detected erythrulose, a four-carbon sugar, in the G+0.693−0.027 molecular cloud near the center of the Milky Way. Published in the journal Nature Astronomy, the study provides evidence that complex prebiotic molecules can form in deep space, potentially seeding early Earth with the essential building blocks for DNA and RNA.
Challenging the Sequential Growth Model of Astrochemistry
The discovery of erythrulose challenges long-standing assumptions about how molecules evolve in space. Traditionally, researchers operated under a sequential growth model, which posited that interstellar molecules developed by adding one carbon atom at a time—moving from one-carbon to two-carbon, and eventually to three-carbon structures.
The research team, led by Dr. Izaskun Jiménez-Serra of the Centro de Astrobiología (CAB), found that erythrulose does not follow this path. In collaboration with chemists from the University of Extremadura and Radboud University, the team determined that the sugar forms through a more efficient process. Simple two-carbon alcohols and aldehydes bond directly within interstellar ices, effectively skipping the three-carbon stage entirely. This mechanism explains why erythrulose is at least eight times more abundant in the cloud than similar three-carbon sugars, none of which were even detected in the region.
Did you know?
Erythrulose is a ketose sugar commonly found on Earth in raspberries and certain sunless tanning products. Its discovery in space marks the first time a sugar has been observed directly in interstellar space.
The Prebiotic Paradox and Earth’s Origins
Sugars are the backbone of life, yet they represent a persistent paradox for scientists studying the origins of biology. While sugars are necessary to synthesize nucleic acids like DNA and RNA, laboratory simulations of early Earth conditions have struggled to produce them in the quantities required for life to emerge. By finding these molecules in deep space, researchers are looking to the stars to explain this deficit.
The team used high-resolution data from the Yebes 40-meter radio telescope in Spain and the IRAM 30-meter telescope in France to identify 12 distinct spectral lines of radio emission. These matched laboratory measurements of erythrulose taken at the University of the Basque Country. Based on the concentration found in the G+0.693−0.027 cloud, the team estimates that between 0.5 and 50 million tonnes of space-based sugar could have been delivered to Earth during the Late Heavy Bombardment, roughly 4.1 to 3.8 billion years ago.
Future Directions in Astrochemistry
This detection serves as a proof of concept for identifying even more complex biological precursors. Study co-author Carlos Briones noted that the discovery opens the door to detecting ribose—the sugar essential to RNA—within similar interstellar environments. As telescope technology becomes more sensitive, the ability to map the distribution of these sugars will provide a clearer picture of how “prebiotic” chemistry functions across the galaxy.
Pro Tip:
When tracking complex molecules, researchers rely on “spectral fingerprints.” By comparing radio emissions from deep space to controlled laboratory samples, they can confirm the chemical composition of distant clouds with high precision.
Frequently Asked Questions
Why is the discovery of erythrulose important?
It provides a potential solution to the “prebiotic paradox,” where Earth-based models fail to explain how enough sugar was present to form the first genetic material. Finding it in space suggests a “delivery” mechanism via asteroid impacts.
How was the sugar detected?
The team used the Yebes 40-meter and IRAM 30-meter radio telescopes to capture spectral lines from the G+0.693−0.027 molecular cloud. These lines were then verified against laboratory data from the University of the Basque Country.
What does this mean for the search for life elsewhere?
The confirmation that four-carbon sugars form in space suggests that the building blocks of life are not unique to Earth and may be distributed throughout the galaxy, potentially facilitating the development of life on other habitable planets.
Are you interested in the latest breakthroughs in astrobiology? Subscribe to our newsletter to receive updates on how researchers are solving the mysteries of our origins.
