Life on Earth may have begun with a little help from the stars.
New research suggests that amino acids—the essential building blocks of proteins—could have hitched a ride to our young planet on grains of cosmic dust, helping spark the first steps toward biology as we know it.
The study, published in Monthly Notices of the Royal Astronomical Society, was led by Stephen Thompson and Sarah Day, scientists at the UK’s Diamond Light Source.
They set out to test how amino acids such as glycine and alanine might survive the extreme conditions of space and be carried to Earth on tiny dust particles traveling through the early solar system.
Amino acids are the foundation of proteins and enzymes, which drive every process in living organisms.
Scientists have long debated whether these molecules first formed on Earth or were delivered from space. The new study offers strong evidence that interstellar dust could have played a crucial role in bringing them here.
To simulate this process, the researchers created tiny particles of amorphous magnesium silicate, one of the main ingredients of cosmic dust.
They then deposited amino acids—glycine, alanine, glutamic acid, and aspartic acid—onto these grains and exposed them to heating, mimicking the warming that dust would experience as it moved closer to the young Sun.
The results were surprising. Only glycine and alanine were able to stick to the silicate particles and form stable crystalline structures.
Alanine proved particularly resilient, remaining intact even at temperatures above its normal melting point.
Interestingly, the two mirror-image forms of alanine (known as L- and D-alanine) behaved differently: L-alanine, the form used in life on Earth, was more reactive and stable under heat.
Glycine, meanwhile, detached from the silicate surface at relatively low temperatures, suggesting it could have been released intact rather than destroyed.
The scientists also tested how surface chemistry affected these outcomes.
By heating some of the silicate particles before adding the amino acids, they removed hydrogen from the surface, creating subtle differences that changed how tightly the amino acids bound.
These small variations could have had a major influence on which molecules survived space travel and were eventually delivered to early Earth.
The findings point to what the researchers call an “astromineralogical selection mechanism” — a natural filtering process in which only certain amino acids can attach to certain dust surfaces.
This means the chemistry of the dust itself could have determined which organic molecules made it through space and into Earth’s atmosphere.
Scientists believe that between 4.4 and 3.4 billion years ago, the planet was bombarded by micrometeorites carrying these compounds. This steady shower of cosmic dust could have supplied more organic material than asteroid or comet impacts, enriching Earth’s early oceans and crust with the ingredients needed for life.
Evidence for this idea comes from modern samples of cosmic dust, such as Antarctic micrometeorites and material collected from comets like Wild 2 and 67P, which contain high concentrations of amino acids and other organic molecules.
This new research strengthens the case that life’s origins may have been cosmic.
Far from being lifeless specks, interstellar dust grains might have acted as tiny chemical couriers, protecting and delivering the molecules that made life possible — not just on Earth, but potentially across the universe.
Source: KSR.
