Much Ado About Ryugu
Uracil, a molecule found in RNA, has been reported in an asteroid.
From media hype, one would think they discovered life in outer space.
Sample dust collected by Japan’s Hayabusa 2 spacecraft from asteroid Ryugu has been analyzed. One of the big finds is uracil, a “building block” of RNA. It’s not that big a deal; uracil has been reported in meteorites before, as have amino acids. Nicotinic acid (a precursor to vitamin B3) was also found. Both molecules were detected in extremely low concentrations (parts per billion). Since uracil and nicotinic acid are six-carbon ring molecules that are used by life, some reporters have hyped the report far beyond reason, acting like this is a major step in explaining the (naturalistic) origin of life. Some are even saying that the building blocks of life were sent to Earth by comets and asteroids. It’s time to calm down and think.
Uracil found in Ryugu samples (Hokkaido University press release 22 March 2023). The scientists are pretty certain that the uracil they found is authentically from the asteroid, not from contamination.
“Scientists have previously found nucleobases and vitamins in certain carbon-rich meteorites, but there was always the question of contamination by exposure to the Earth’s environment,” Oba explained. “Since the Hayabusa2 spacecraft collected two samples directly from asteroid Ryugu and delivered them to Earth in sealed capsules, contamination can be ruled out.”
Nevertheless, analysis was done in lab conditions with equipment on Earth. Can they rule out contamination in all the pieces that touched the samples?
The researchers extracted these molecules by soaking the Ryugu particles in hot water, followed by analyses using liquid chromatography coupled with high-resolution mass spectrometry. This revealed the presence of uracil and nicotinic acid, as well as other nitrogen-containing organic compounds.
The results were reported in Nature Communications 21 March 2022 by Oba et al., “Uracil in the carbonaceous asteroid (162173) Ryugu.” One cannot “see” these molecules, however, within the sealed capsule. The capsules had to be opened and the contents analyzed. Any living thing in contact with the samples would have contained uracil. Typically, sterilization is a matter of degree, not absolute purity.
The Methods section indicates that the samples were subjected to severe treatment with equipment and hot water baths on our planet which is permeated with nitrogen-containing organic compounds in the air, in water, on surfaces, on human skin, and in bacteria (see quote at bottom of this article)*. Nevertheless, for present purposes, we can assume they took precautions enough to justify the claim that extraterrestrial uracil was detected from the asteroid. What does it mean?
Amino Acids, Too
Another paper about the Ryugu analysis announced finding amino acids in the asteroid dust:
Potiszil et al., “Insights into the formation and evolution of extraterrestrial amino acids from the asteroid Ryugu,” Nature Communications, 17 March 2023.
The authors of this paper do not say whether the amino acids found are racemic (mixture of left- and right-handed molecules). But they do seem to argue that prebiotic amino acids would likely be racemic:
The origin of life on Earth is a contentious issue, with a variety of potential environments being proposed, including oceanic hydrothermal vents and terrestrial hot springs. However, one thing that is certain, is that life would have required amino acids at some point in order to synthesise proteins, which are responsible for a number of biological functions, such as catalysing metabolic reactions, the replication of DNA, transportation of molecules and giving structure to cells and organisms. While it may have been possible to generate amino acids on the early Earth, only extraterrestrial sources have been found to contain abiotically synthesised amino acids with enantiomeric excesses of L-amino acids. As such, an extraterrestrial origin for at least some of the building blocks of life has been proposed.
This statement indicates two things. The “enantiomeric excess” (predominance of one hand over the other) would be unlikely to form on the early Earth before living cells ensured they were left-handed (L-amino acids). Homochirality in amino acids is diagnostic of life.
Second, if an enantiomeric excess of L-amino acids were found in an extraterrestrial source, how could it arise naturally? They don’t say. A natural formation would be expected to be racemic without a plausible mechanism for producing the enantiomeric excess. But if extraterrestrial sources are found with a predominance of L-amino acids, why don’t they consider the possibility that the homochiral molecules came from life on Earth? It’s a shame they ignore this important question in the paper.
Send in the Clowns
Uracil in a meteorite in parts per billion has no more relevance to the origin of life than a bit of diamond dust in a mine has to a spontaneous, naturalistic wedding (remember, diamond is a carbon compound, too, as is hydrogen cyanide). The paper says nothing about the origin of life, and makes no claims about biology (other than two references to papers about the “RNA World” scenario). But look at how some reporters took this “building block of RNA” and ran with it into Darwin Fantasyland.
Samples from asteroid Ryugu contain one of the building blocks of RNA (New Scientist, 21 March 2023). “The Hayabusa 2 spacecraft brought back samples from Ryugu in 2020,” writes Leah Crane, “and an analysis of a tiny portion of those samples has revealed key ingredients for life.” She performs divination on the black pebbles in the photo and sees spirits emerging from them:
Samples from the asteroid Ryugu contain uracil, one of the four building blocks of RNA, as well as niacin and other compounds that are important for living organisms. This lends credence to the idea that the ingredients for life were brought to Earth by space rocks.
Key building block for life discovered on distant asteroid Ryugu — and it could explain how life on Earth began (Live Science, 22 March 2023). Reporter Ben Turner is overcome with hypnosis engendered by imagined vapors of uracil emanating from photos of the tiny pebbles from Ryugu. They make him dream of faraway worlds crawling with alien life forms. He uses the word life a dozen times.
For the first time, scientists have found one of the key building blocks for RNA on an asteroid in space. The discovery indicates that the blueprints for life may have been brought to Earth from beyond our planet, and that rudimentary forms of life could exist elsewhere in the solar system.
Life emerges better with electricity, Turner thinks. He fantasizes images of the Miller spark-discharge apparatus from deep within his altered state of consciousness switching life on everywhere in the universe!
Previous analyses of meteorites found on Earth revealed that the fallen space rocks contained the five nucleobases essential for building life as we know it, but scientists were unsure if they were there before they plummeted to Earth or got onto the meteorites by contamination with our atmosphere. But the analysis of Ryugu’s contents, which were scraped from the asteroid’s surface before being launched back to Earth, has provided a significant clue that the cosmos could be teeming with life-sparking molecules.
This should be an easily-testable hypothesis. Put uracil on sterile rocks and wait a few million years.
Building block of life found in sample from asteroid Ryugu (Space.com, 22 March 2023). Keith Cooper, part of the same Darwin-drunk science reporting apparatus as Live Science, catches the same euphoria from uracil sniffing.
The discovery is incredibly important for astrobiologists. It is a step along the road to understanding the origin of life, and whether the processes that led to the appearance of life on Earth can be repeated elsewhere in the universe.
His mind-expanding drug (uracil vapor) mixed with Darwine sends him into fantastic visions of a universe teeming with space aliens:
Another possibility is that uracil and other nucleobases may pre-date the formation of our solar system. They may have been formed in deep space via photochemical reactions — the action of ultraviolet light on organic molecules — on ices in interstellar clouds from which the solar system, and other planetary systems including their asteroids, formed. The basic stuff of life as we know it on Earth could potentially be spread across the galaxy. If nucleobases are common in the universe, then any hypothetical alien life may also possibly use RNA and DNA.
Turner and Cooper appear eager, like Jimmy Carter said on the Voyager Record, to “join a community of galactic civilizations.”
New asteroid sample study offers further hints of space origin for the building blocks of life on Earth (The Conversation, 21 March 2023). Trevor Ireland from the University of Queensland makes a fool of himself by thinking this has anything to do with the origin of life. “Some of the so-called ‘building blocks of life’ may have been surprisingly common in the early Solar System,” he says, making it all sound so simple.
At the most basic level, the development of life is a matter of combining simple organic molecules into increasingly complex compounds that can participate in the myriad reactions associated with a living organism.
Ireland confirms that the amino acids found on Ryugu were racemic:
Life on Earth relies on left-handed amino acids, but both forms are equally common in Ryugu samples – which indicates the molecules found on Ryugu are not signs of life.
A Dose of Realism
Uracil is one of five nucleobases used in the genetic code. In the RNA code (A,U,G,C) uracil replaces thymine in DNA (A,T,G,C). Thymine is methylated uracil, so they are similar. Thymine may confer added stability to the DNA molecule, which needs to last longer than short-lived RNA molecules in cells.
The uracil we know on Earth is found in life, and we humans get it from our food. Plants synthesize nucleobases like uracil de novo from precursor molecules; we can get nucleobases from animal protein as well as from plant sources. To be useful in the genetic code, though, a nucleobase must be attached to a sugar (deoxyribose for DNA, ribose for RNA) and a phosphate, forming a nucleotide. The nucleotides, furthermore, must connect in long strands (single for RNA, double for DNA). The nucleotides are paired with opposite bases by hydrogen bonds (A to T or U, G to C).
Importantly, it is the sequence of bases that makes up the genetic code. This means that uracil in a meteorite is no more meaningful than a random pile of toy blocks with “U” stamped on them. Toy blocks with multiple letters as in Scrabble can be arranged in words, and words into sentences and paragraphs by intelligent agents. But individual letters in both Scrabble and RNA have no meaning.
Was Contamination Ruled Out?
In the lab, uracil can be synthesized from other organic molecules by intelligent design. Can it form spontaneously on asteroids? Some scientists believe that UV radiation on ices can produce it, if certain precursor molecules, such as urea or PAHs (polycyclic aromatic hydrocarbons) have also formed; however, the best evidence would be the detection of pure nucleobases on uncontaminated extraterrestrial sources like asteroids, comets or other planets or moons. Because the nucleobases are difficult to form naturally, some scientists see them as evidence of life.
This raises the question of contamination. A previous detection of uracil in the Orgueil meteorite that fell in 1864 could not rule out Earth contamination. The research team claims the samples returned by Hayabusa-2 were uncontaminated. Yet a look at the paper’s methods shows some possible avenues for contamination.
The acid-hydrolysate of the hot water extracts from the Ryugu samples and the Orgueil meteorite was introduced into an HPLC/ESI-HRMS instrument with a mass resolution of 140,000 at a mass-to-charge ratio (m/z) of 200. The analytical system comprised an Ultimate 3000 and Q-Exactive Plus (Thermo Fischer Scientific) equipped with a reversed-phase separation column (HyperCarbTM, 150 mm length × 1.0 mm i.d., particle size 5 μm, Thermo Fisher Scientific) at 40 °C and operated in positive ion mode. Validations of analytical methods were also performed using a 1290 Infinity II coupled with a 6230 time-of-flight mass spectrometer (Agilent Technologies). The eluent program for the HPLC was as follows: solvent A (water + 0.1% formic acid) and solvent B (acetonitrile + 0.1% formic acid) = 99:1 at t = 0 min, followed by a linear gradient of A:B = 70:30 at 20 min, and maintained at this ratio for 25 min. The flow rate was 50 μL/min and the column temperature was kept at 40 °C. The injection volume was 5 μL. The mass spectra were recorded in positive ESI mode with an m/z range of 50–600 at the first trial, and the range was narrowed to 111–131 in order to increase the signal to noise ratio of the target species. The voltage was set to 3.5 kV for positive ESI. The capillary temperature was 300 °C.
Clearly, a number of instruments were used in the analysis, and a critic of the methods would have to check whether the instruments and reagants were sterile, and follow the chain of handling of all materials during the analysis.
There are additional questions to raise that the secular reporters never think of, so we have to do their job of critical thinking and balanced reporting for them.
Even if everything handling the samples was 100% sterile, a question could be raised about the asteroid itself. Ryugu is a near-Earth asteroid. Could it pick up any uracil from proximity to Earth? One creation scientist, Dr Walter Brown, proposes that asteroids and comets exploded out from the fountains of the great deep at the onset of the Flood. This would never be accepted by secular scientists, of course, but his idea gained some support when the scientists for the Stardust mission were shocked to find salts and organic molecules in samples returned from a comet. The molecules and minerals required heat to form, and could not have been expected from a comet’s supposed origin in the outer icy reaches of the solar system.
It might be possible to suspect contamination if the organic molecules (amino acids and bases) were homochiral (one-handed), since DNA, RNA and amino acids are homochiral and could not be expected if formed naturally outside of life. Even so, heterochiral or mixed-handed (racemic) molecules, which the researches claim to have found, would not rule out Earth contamination, since some chiral molecules racemize over time.
The biggest problem with the over-hyped reports is the assumption that a building block of RNA is a step closer to understanding how life originated. As we have pointed out repeatedly, this is like claiming that a discovery of iron on Mars suggests that skyscrapers will be discovered there. It’s not the building blocks but the way they are assembled that makes the difference.
Consider how foolish it is to think that asteroids like Ryugu transported the building blocks of life to Earth, and then Earth used them to construct the first living cell. For one thing, a uracil molecule landing in the Atlantic Ocean will be a lonely, lifeless thing, unlikely to ever meet another nucleobase molecule landing in the Pacific. Same with amino acids and any other “prebiotic” molecules. The concentration would have to be enormously high for the molecules to meet up and start a new project. And then, for amino acids, they tend to fall apart in water.
Plus, uracil by itself is useless. What good is a few uracil molecules adrift? Even if they could be preserved somehow, they don’t spell anything. As stated earlier, they are as useless as toy blocks all stamped with the latter U.
Nucleobases are also hard to make. In living things, complicated algorithms make the nucleobases from scratch in multiple steps, with enzymes and molecular machines. If you have a few uracil molecules floating around at random in the oceans, they will never just happen to link up to phosphates and ribose—another complex sugar that rapidly degrades in water. Why don’t the reporters and researchers talk about these things?
Only the wildest imaginations can believe that these useless molecules will somehow come together instead of just fall apart. The videos “Long Story Short” by the Discovery Institute and Dr James Tour‘s refutations of origin-of-life claims are sufficient to consign such speculations to the realm of science fiction and fantasy.