Astronomers have discovered a sugar molecule called erythrulose in an interstellar cloud of gas and dust, providing a major clue to the origin of life on Earth. The finding, published in Nature Astronomy, shows that complex organic molecules essential for life can form in space before stars or planets exist.
Discovery in the Milky Way
Researchers from Spain's Centre for Astrobiology near Madrid detected erythrulose in G+0.693−0.027, a thin interstellar medium about 27,000 light-years from Earth. Using two powerful radio telescopes, they analyzed the frequencies emitted by spinning molecules in the cloud. The sugar is composed of four carbon atoms, eight hydrogen atoms, and four oxygen atoms — the same molecule found in raspberries, melons, and self-tanning lotions.
Dr. David Benoit, a molecular physicist at the University of Hull who was not involved in the study, told Metro: "It is not uncommon to spot molecules in this part of space. But this is one of the first times this type of sugar has been found out there."
How sugar forms without life
The team verified their results repeatedly, initially disbelieving they had found a cosmic sugar reservoir. Erythrulose forms when two organic compounds, glycolaldehyde and ethylene, combine. Dr. Benoit explained: "This process is statistically rare, considering how big space is, but tiny 'dust grains' help make these meetings more likely by creating little islands where molecules congregate."
The discovery challenges previous assumptions that sugar on Earth originated solely from meteorites. Last year, ribose — a larger sugar — was found inside an asteroid. Scientists have struggled to recreate the chemical conditions for sugar formation in laboratories, making the space-based finding even more significant.
Implications for life's origins
The research suggests that up to 500,000,000,000 kilograms of sugar could have arrived on Earth as it formed billions of years ago. This sugar may have triggered the chemical reactions leading to life around 4.1 billion years ago, based on fossil evidence of ancient microbes. Other essential building blocks include carbon, water, and nitrogen.
"Sugars are essential components of living organisms," Dr. Benoit said. "Thus finding complex organic molecules linked to life 'building blocks' in space can help further explain where our chemistry comes from." He added that a random combination of these molecules "could have ultimately led to primitive self-replicating systems."
