Ryugu asteroid samples contain all DNA and RNA building blocks, bolstering origin-of-life theories

Samples from asteroid Ryugu contain all nucleobases required for DNA and RNA, including uracil, adenine, guanine, cytosine, and thymine, supporting the idea that such molecules are widespread in the solar system. The study also found a unique correlation between nucleobase ratios and ammonia concentration, suggesting a previously unrecognized formation pathway in early solar system materials.

All the essential ingredients to make the DNA and RNA underpinning life on Earth have been discovered in samples collected from the asteroid Ryugu, scientists said last week.
The discovery comes after these building blocks of life were detected on another asteroid called Bennu, suggesting they are abundant throughout the solar system.
The asteroids that hurtle through our solar system give scientists a rare chance to study this possibility.

In 2014, the Japanese spacecraft Hayabusa-2 blasted off on a 300-million-kilometer (185-million-mile) mission to land on Ryugu, a 900-meter-wide (2,950-feet-wide) asteroid.

It successfully managed to collect two samples of rocks weighing 5.4 grams (under a fifth of an ounce) each and bring them back to Earth in 2020.

Research in 2023 showed that these samples contained uracil, which is one of the four bases that make up RNA.
While DNA, the famed double helix, functions as a genetic blueprint, single-strand RNA is an all-important messenger, converting the instructions contained in DNA for implementation.

Last Monday, a new study by a Japanese team of researchers in Nature Astronomy demonstrated that the samples contained all the "nucleobases" for both DNA and RNA.

These included uracil as well as adenine, guanine, cytosine and thymine.

This means their presence indicates that primitive asteroids could produce and preserve molecules that are important for the chemistry related to the origin of life.
The discovery also "demonstrates their widespread presence throughout the solar system and reinforces the hypothesis that carbonaceous asteroids contributed to the prebiotic chemical inventory of early Earth," according to the study.
With this and the results from Bennu, we now have a very clear idea of which organic materials can form under prebiotic conditions anywhere in the universe.
Last year, the same building blocks were found in fragments brought back to Earth by NASA from the asteroid Bennu.

Scientists have also detected their presence in the meteorites Orgueil and Murchison, which were part of asteroids that fell to Earth.
Scientists also identified a correlation between the ratios of the building blocks and the concentration of another important chemical for life: ammonia.

Because no known formation mechanism predicts such a relationship, this finding may point to a previously unrecognized pathway for nucleobase formation in early solar system materials.
This discovery has important implications for how biologically important molecules may have originally formed and promoted the genesis of life on Earth.

Toshiki Koga et al, A complete set of canonical nucleobases in the carbonaceous asteroid (162173) Ryugu, Nature Astronomy (2026). DOI: 10.1038/s41550-026-02791-z

Humans in The Andes Appear to Have Evolved a Strange Genetic Ability

For thousands of years, humans living high in the Argentinian Andes have relied on drinking water that would make most people deathly ill.
There, naturally occurring arsenic in volcanic bedrock leaches into the groundwater, contaminating the local water supply with levels of the toxic metalloid that would pose serious health risks to most human populations.

But for one group in northern Argentina, natural selection may have provided an unusual genetic advantage.

According to a DNA analysis of people across western South America, a population in the Argentinian Andes carries a gene variant that likely helps them metabolize arsenic more safely.
Scientific data show that adaptation to tolerate the environmental stressor arsenic has likely driven an increase in the frequencies of protective variants of AS3MT, providing the first evidence of human adaptation to a toxic chemical.

In 1995, scientists noted that women from the Argentinian Andes had a "unique" ability to metabolize arsenic, as evidenced by metabolites in their urine.
When arsenic enters the body, enzymes convert it through several chemical forms. One of these intermediate forms, called monomethylated arsenic (MMA), is particularly toxic. A later form, dimethylated arsenic (DMA), is easier for the body to excrete in urine.

People in San Antonio de los Cobres tended to produce less of the toxic intermediate and more of the easily excreted form, suggesting their bodies were unusually efficient at processing arsenic.
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Researchers found that a cluster of genetic variants near the AS3MT gene that strongly influenced how the body processes arsenic. These variants were far more common in people from San Antonio de los Cobres than in genetically similar populations in Peru and Colombia.

The variants appear to make the body more efficient at converting arsenic into forms that can be safely excreted in urine, reducing the buildup of the most toxic intermediate compounds – a result that neatly aligns with earlier studies of arsenic metabolites in urine.
While arsenic contamination is common around the world, very few communities have lived with such high levels of exposure for long periods of time.

In San Antonio de los Cobres, people have lived with arsenic in their groundwater for thousands of years – long enough for natural selection to favor traits that reduce vulnerability to arsenic's toxic effects.
Research suggests similar genetic signals may also appear in other Andean populations exposed to arsenic for generations, supporting the findings that long-term exposure can drive genetic tolerance, and hinting that the adaptation may be more widespread across the region.

https://academic.oup.com/mbe/article/32/6/1544/1074042?login=false

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