Astronomers have detected a type of sugar that’s found in raspberries and self-tan lotions near the centre of the Milky Way. A study published this week in the journal Nature Astronomy revealed evidence of erythrulose, a simple sugar, in interstellar gas and dust clouds between stars.
The discovery may conjure up images of a “civilisation of pale, safety-conscious frugivores” in outer space, said The Guardian science editor, Ian Sample, but for astronomers it is significant because “it shows that compounds important for life can form in the frigid expanse between the stars”.
Erythrulose is a monosaccharide (simple sugar) like glucose and fructose, but it is the “most complex sugar spotted beyond our Solar System”, said Nature. Two-carbon simple sugars have previously been detected on meteors and asteroids, but this is the first time a four-carbon “true sugar” has been spotted in interstellar space.
‘Exceptionally sensitive observations’
Using radio telescopes in Spain, researchers collected data from a dust cloud called G+0.693-0.027 near the centre of the Milky Way. After comparing these signals to samples in the lab, they detected traces of erythrulose. The discovery was enabled by “the combination of exceptionally sensitive observations, extensive frequency coverage, and highly accurate laboratory spectroscopic data”, study co-author Izaskun Jiménez-Serra told Live Science.
The findings indicate that erythrulose was probably produced by chemical reactions on tiny interstellar dust grains, which then “rained down” on nearby objects, including planets, or were incorporated into comets. It’s thought that “Earth underwent a period of heavy bombardment from asteroids and comets” around the time that the earliest signs of organic life began to emerge “about four billion years ago”, said Nature. This might have been how sugar molecules were brought to our planet’s surface.
Origin of life
“Sugar does more than sweeten tea and powder doughnuts”, said The Associated Press. “Different varieties fuel our cells and even make up DNA,” so scientists are “itching to know how sugars form because they’re a key ingredient for life as we know it”. Erythrulose itself “isn’t essential for life, but can easily convert to a form that’s thought to be crucial to kick-starting life on Earth”.
It is “especially tantalising” to think that erythrulose might have acted a “feedstock” for the more complex sugars that evolved into nucleic acids – the “building blocks of modern-day DNA and RNA”, said Nature.
“That’s why the detection of erythrulose is so relevant for the origins of life,” said Jiménez-Serra. And, if we could discover even more complex sugars in the Milky Way, more light could be shed, astrophysicist Anthony Remijan told Nature. “An actual building block of RNA and DNA: that would be the next big thing.”
Evidence of erythrulose ‘particularly relevant’ for origin-of-life research