Asteroid evidence for life on earth coming from outer space?
Do amino acids found on Ryugu (the first asteroid to be sampled) support chemical evolution?
Stephen R. from the USA wrote to ask for our comment on the recent amino acid discovery1 in the samples brought back from the asteroid, Ryugu.
Scientists have taken samples from the Ryugu Asteroid and recently found amino acids in the asteroid. I didn’t see anything about proteins found in it or anything greater but this will be notable for the naturalists claiming panspermia or abiogenesis.I wanted to bring this to your attention so it could be addressed. How could those amino acids have formed and how does this affect the case for naturalism and panspermia?
Thank you for your email.
The analysis of the Ryugu samples is exciting because the Hayabusa2 mission is the second ever space probe to collect a sample from an asteroid and deliver it back to earth.2
Earlier examinations of meteorites,3 (the rocky remnants of asteroids/comets that land on earth) have also revealed amino acids. Although unlikely, meteorite sample analysis can suffer from terrestrial contamination. This possibility was borne out in the reanalysis of the Martian meteorite, ALH84001: The announcement of the discovery of amino acids in 1996 was later disproved in a 1998 study.4 So the Ryugu sample is an interesting step in the discovery of extra-terrestrial amino acids, as the likelihood of contamination is much lower.5
For the naturalist, this report holds further allure because under the nebular hypothesis, asteroids formed along with the earth at the beginning of the solar system, 4.5 billion years ago. But unlike the earth, asteroids have not experienced the effects of weathering (asteroids have no atmosphere and therefore no weather) or plate tectonics. Therefore, asteroid samples are thought to be 4.5 billion years old (older than any earth rocks).
Additionally, rather than supposing that life began on earth, many of those holding to abiogenesis (see box) believe life had an extra-terrestrial origin. This theory is known as panspermia (see below). So, finding amino acids on an asteroid is exciting for the naturalist.
Abiogenesis is the genesis (the creation) of biotic (living) material from nonliving material. Encyclopedia Britannica correctly describes it as the idea that life arose from non-life more than 3.5 billion years ago on Earth. This idea directly contradicts the experimentally verified law of biogenesis (only life begets life). But without a creator God, the naturalist is forced to accept abiogenesis as a fact. Another name for abiogenesis is chemical evolution.
‘…How could those amino acids have formed …?’
This is a historical science question, therefore several different answers exist. They likely fall under the following three categories:
- As God created the heavenly bodies on day 4, the amino acids found may have been part of the original creation. In which case these amino acids were created in Ryugu’s parent body on day 4.
- Alternatively, the amino acids could have formed from UV irradiation of Ryugu’s constitute chemicals.
- One other possible scenario is that the amino acids were created by UV irradiation of chemicals found in interstellar dust grains in the interstellar medium. These grains were then transported to Ryugu by interstellar winds.
The famous Miller-Urey experiment (see figure 1), while falsely sold in schools, museums, and TV shows as proof of abiogenesis, did show that very small amounts6 of simple amino acids can be formed from reducing agents (hydrogen-rich compounds), in the presence of a spark discharge (simulating a lightning strike or UV radiation).
Favouring the last 2 choices is the fact that extra-terrestrial amino acids are not homochiral (see figure 2). Amino acids synthesised from chemicals are racemic (a mixture of left and right handed), but nearly all biological polymers are homochiral, with amino acids being left-handed.
Panspermia is the idea that life exists throughout the universe and has come to earth on meteorites. While there have been many well-known proponents of Panspermia since its first mention in the fifth century by the Greek Philosopher Anaxagoras, it is only recently that evolutionary scientists have given it more credibility.
In 1929, JBS Haldane proposed that the early earth’s atmosphere was reducing, i.e. rich in hydrogen or hydrogen-rich compounds such as ammonia and methane. Before this, many evolutionary researchers assumed that the earth’s atmosphere had never varied greatly from today’s, made up of nitrogen, oxygen, and carbon dioxide (see table 1). When it was realised that the building blocks of life essential biopolymers, like sugars and amino acids, were not stable on their own in oxidising environments, the opinion shifted, starting with JBS Haldane and Russian biochemist Aleksandr Oparin.
However, in the last 20 years, multiple discoveries of highly oxidised chemicals in minerals (supposedly 4+ billion years old)7 have caused many evolutionists to once again believe that the earth’s atmosphere was oxidising from the beginning.
But as Haldane realised, an oxygen-rich early atmosphere, like today’s, would destroy amino acids and prevent their formation. Hence the increased interest in panspermia: An extraterrestrial body may have the reducing conditions required ….
|Theoretical Reducing Atmosphere
|Earth’s Present Oxidizing Atmosphere
|Methane (CH4), Carbon Monoxide (CO)
|Carbon Dioxide (CO2)
|Ammonia (NH3), Nitrogen (N2)
Are amino acids on an asteroid sufficient to promote abiogenesis via panspermia as a plausible idea?
While amino acids are the monomers needed to build proteins, four other monomers are needed to build the three other life-essential biomolecules: lipids, carbohydrates, and nucleic acids (DNA/RNA). The report does not mention that these were found.
It is important to note that all the above compounds, while organic, are abiotic—they are nonliving. So even if chemists were able to synthesize all of them from chemicals in the right amounts, they still could not claim abiogenesis is possible.
Have other researchers found extra-terrestrial proteins?
A paper submitted to the preprint archive (arXiv.rg) on 22 Feb 2020,8 claims to have found a protein in a meteorite.9 But over two years on from the preprint there is no sign of the paper in any peer-reviewed journal. And shortly after the popular media discovered this story, Origin of Life researchers quickly dismissed the findings, one commenting:
“I am not impressed by this report.”10
Another, Lee Cronin of Edinburgh University, said:
‘The protein they claim to have found is also unlikely to occur in nature.’11
Lots of proteins occur in nature. They are the building blocks of all life! But given Lee Cronin’s naturalistic worldview, we understand he is saying that the potential protein in question is unlikely to form naturalistically. Given that he is an abiogenesis believer he must believe that some proteins form naturalistically.
Could the amino acids found on Ryugu naturalistically combine to form a protein?
In all living cells, proteins are built by cellular particles called ribosomes. They receive instructions (messenger RNA) and amino acids on transfer RNA, to build polypeptide chains,12 connecting them by peptide synthesis (see figure 3) in the correct order. The order of the amino acids and the way in which the polypeptide is folded determines the proteins’ function.
Given the correct amino acids, functional proteins can be polymerised in the lab, provided that:
- Scientists can use natural enzymes to overcome the polymerisation problem.
- The amino acids are placed in an order that creates a functional protein.
Note that provision (2) requires the intelligence of the scientist. While in the body, genetic code is used to correctly order the proteins: Each gene is made up of between five hundred to two million nucleotide base pairs. Experience tells us that intelligent codes are created by intelligent minds! It is then reasonable to conclude that proteins testify to an intelligent creator.
Although the Hybusa 2 mission only found two amino acids, let’s give the naturalist the benefit of the doubt and suppose that the 20 amino acids needed to build the proteins essential for life could have been produced by some Miller-Urey type process on an asteroid like Ryugu.
Now let’s consider the probability that on this hypothetical asteroid, the amino acids were able to arrange themselves in a chain to make just one protein,13 purely by chance, with no intelligence allowed.14
We will take it as a given that the asteroid miraculously has a pool of the 20 proteinogenic amino acids in close proximity, and none of the 140+ non-proteinogenic amino acids were present.
An average protein is made up of a chain of circa 300 amino acids15 So the number of possible combinations of the 20 different amino acids in an average protein is:
20300=2.037×10390 ≈ 10390
A minority of these possible combinations of amino acids result in a functional protein,16 and suboptimal protein sequences may exist that are not currently observed but are capable of performing a relevant function long enough for natural selection to choose more optimal sequences.
If there were one million billion possible functional sequences (that’s one thousand trillion or 1015), the probability of randomly obtaining a functional sequence is then:
This is a one in a number followed by 375 zeros chance! This is beyond improbable, and yet we are only considering the probability of constructing one protein by chance.
While one thousand trillion seems like a very large guess, for the number of possible functional amino acid sequences (if one is very generous in how they define functional) it could be argued that functional sequences are much more common. Molecular Biologist Douglas Axe in a 2002 paper17 comes up with a restrictive definition for a functional protein by looking at the amino acid sequence requirements for an enzyme (protein) to fold in a way that will allow the active site to remain functional. He starts with a less than average size protein, beta-lactamase, made up of 153 amino acids. 153 amino acids can be arranged in a total of 20153 ≈ 10199 ways. He goes on to calculate that the probability of randomly obtaining a functional sequence is then 1 in 1077.
Stephen Meyer, of the Discovery Institute, uses Douglas Axe’s findings to calculate the probability of obtaining a functional sequence for a hypothetical protein of 150 amino acids, which turns out to be 1 in 1074.
Not only should the amino acids be in the correct order, but every amino acid should also be connected by a peptide bond. Estimating the prevalence of peptide bonds between amino acids at 50%18 in a sequence of one hundred and fifty, adds a probability of 1 in 2149 ≈ 1 in 1045.
Miller-Urey-like chemical reactions without enzymes produce a racemic mixture of 50% left-handed and 50% right-handed amino acids. Yet the amino acids found in proteins are all left-handed (except for glycine, which is achiral). This means for the 150 amino acid long protein, there is a 1 in 1045 chance of randomly having every amino acid in the left-hand form, and therefore able to form a peptide bond.
Stephen Meyer used the above parameters to calculate the probability of a small functional protein forming by chance to be:
To put the unlikeliness in context, consider the size of the observable universe and the time since the supposed big bang:
- 1080 elementary particles in the known universe.
- 1017 seconds since the supposed Big Bang.
You could use the above probabilities with the maximum number of atomic interactions per second, 1012, to calculate that there are a maximum possible 10109 interactions since the supposed beginning of the big bang. Using these numbers, the probability that one protein was created by chance since the beginning of the big bang (given the unlikely event that only the correct 20 amino acids were present and close enough to one another), is:
Still a hugely small number! So, we can conclude: no; a protein cannot form by chance on an asteroid.
This is then an unbridgeable step for abiogenesis. If proteins cannot form by chance, then life cannot come about by chance.
Also, consider we have only looked at the possibility of one protein coming together by chance. The bacterium Mycoplasma Genitalium, has the smallest known genome of any organism with 482 genes, and synthetic biologists have predicted that the smallest number of protein-coding genes a hypothetical single-celled organism could have is 387.19
Protein-first-abiogenesis ideas then need to figure out how the second protein formed! When did DNA come about to code for proteins, and where did the ribosomes to synthesize the subsequent proteins come from? How did the lipids come about and how did they then form the cell membranes to contain all this machinery, protect it, and allow in nutrients …? The list goes on.
A 2009 New Scientist article stated that:
“There is no doubt that the common ancestor possessed DNA, RNA and proteins, a universal genetic code, ribosomes (the protein-building factories), ATP and a proton-powered enzyme for making ATP. The detailed mechanisms for reading off DNA and converting genes into proteins were also in place. In short, then, the last common ancestor of all life looks pretty much like a modern cell.”20
The philosopher, Karl Popper saw the problem of needing DNA to create proteins at the same time as needing proteins to translate DNA:
“What makes the origin of life and of the genetic code a disturbing riddle is this: the genetic code is without any biological function unless it is translated; that is, unless it leads to the synthesis of the proteins whose structure is laid down by the code. But … the machinery by which the cell (at least the non-primitive cell, which is the only one we know) translates the code consists of at least fifty macromolecular components which are themselves coded in the DNA. Thus the code can not be translated except by using certain products of its translation. This constitutes a baffling circle; a really vicious circle, it seems, for any attempt to form a model or theory of the genesis of the genetic code.
Thus we may be faced with the possibility that the origin of life (like the origin of physics) becomes an impenetrable barrier to science, and a residue to all attempts to reduce biology to chemistry and physics.”21
Sir Fred Hoyle said:
“The likelihood of the formation of life from inanimate matter is one to a number with 40,000 naughts after it … It is big enough to bury Darwin and the whole theory of evolution. There was no primeval soup, neither on this planet nor any other, and if the beginnings of life were not random, they must therefore have been the product of purposeful intelligence.”22
How do ‘Origin of Life’ researchers react to these probabilistic hurdles?
Refreshingly, unlike the TV shows and high school textbooks, it is much harder for Origin of Life researchers to turn a blind eye to these inconsistencies. Highly respected origin of life researchers Elbert Branscomb and Michael Russell, originators of the hydrothermal vent model (the idea that abiogenesis occurred close to a fissure on the seafloor) say:
“We claim in particular that it is untenable to hold that life-relevant biochemistry could have emerged in the chemical chaos produced by mass-action chemistry and chemically nonspecific “energy” inputs, and only later have evolved its dauntingly specific mechanisms (as a part of evolving all of the rest of life’s features.”23
So, do they accept a creator God? No, instead they go on to attribute god-like characteristics to ‘natural selection,’ supposing it selected the correct chemicals to create the first living cell. But in a supposed pre-life hydrothermal vent or chemical pond, nothing is reproducing. If nothing is reproducing, how can preferential selection occur? This question (and its answer) are conspicuously absent from their writings.
The information theorist Hubert Yockey (a non-creationist) summarises:
“The belief that life on earth arose spontaneously from non-living matter, is simply a matter of faith in strict reductionism and is based entirely on ideology.”24
And he calls out origin of life research:
“ … Belief in a primeval soup on the grounds that no other paradigm is available is an example of the logical fallacy of the false alternative. In science it is a virtue to acknowledge ignorance. This has been universally the case in the history of science as Kuhn (1970) has discussed in detail. There is no reason that this should be different in the research on the origin of life.”25
The Hayabuss 2 mission is a fantastic feat of experimental science, and the amino acid discovery is of great interest, but the abiogenesis idea remains dead in the water (water being the universal solvent for chemical reactions, and yet the enemy to peptide bonds!). Panspermia advocates purport that life flew into our solar system and collided with earth, thereby suggesting that the source of intelligence is way out there. The discovery of Oumuamua shows that comets from other star systems are possible. Whichever star-system life came from, what was the source of the intelligence? The problem of abiogenesis, a.k.a. chemical evolution, still exists. Life from non-life remains a miracle in need of an explanation.
I hope this response is helpful
References and notes
- Pultarova, T., Pristine asteroid Ryugu contains amino acids that are the building blocks of life, space.com/asteroid-ryugu-samples-analysis-hyabusa2, 10 March 2022. Return to text.
- This sample arrived on earth in 2020. The first ever sample from an asteroid, was from the Japanese Aerospace Exploration Agency’s original Hayabusa mission and was delivered to earth in 2010. NASA’s OSIRIS-REX mission was the third mission to collect an asteroid sample in October 2020, but NASA’s sample has not yet returned to earth. Return to text.
- Kvenvolden, K. et al., Evidence for extraterrestrial amino-acids and hydrocarbons in the Murchison meteorite, Nature 228 (5275): 923–926, 1970. Return to text.
- Jull, A., et al., Isotopic evidence for a terrestrial source of organic compounds in Martian meteorites ALH48100 and Elephant Moraine 79001, Science279(5349):366–369, 1998 Return to text.
- While the Hayabusa samples come direct from the asteroid (as opposed to from a meteorite), the possibility of terrestrial contamination exists. The Japanese space agency’s new planetary material sample curation facility looks to reduce this risk. Opened in 2007, it is the most recently built preservation facility. Return to text.
- The yields of the amino acids glycine and alanine were 1.05% and 0.75% respectively. Return to text.
- Trail, D. et al., The oxidation state of Hadean magmas and implications for early Earth’s atmosphere, Nature 480:79–82, 1 Dec 2011 | doi:10.1038/nature10655. Return to text.
- McGeoch, M. et al,. Hemolithin: a Meteoritic Protein containing Iron and Lithium, arxiv.org/abs/2002.11688 Return to text.
- Prostak, S., Researchers Find Extra-terrestrial Protein in Meteorite Acfer 086, sci-news.com/space/hemolithin-08267.html, 26 Mar 2020. Return to text.
- Jeffrey Bada quoted on space.com/possible-extraterrestrial-protein-meteorite.html, 4 Mar 2020. Return to text.
- Crane, L., Have we really found an alien protein inside a meteorite?, newscientist.com/article/2235981-have-we-really-found-an-alien-protein-inside-a-meteorite, 3 Mar 2020 Return to text.
- An animation illustrating how proteins are formed: youtube.com/watch?v=gG7uCskUOrA Return to text.
- The human body needs hundreds of thousands of different proteins to work! Molecular biologists generally agree that there are about 20,000 different types of proteins in human bodies (because the human genome project counted 20,000 protein coding genes). But some report that there could be billions of protein species: Ponomarenko, E. et al., The Size of the Human Proteome: The Width and Depth, International J. Analytical Chemistry 7436849, 2016 | doi:10.1155/2016/7436849. There are a number of known sources of the unknown proteome, the main one being differential splicing of RNA, which causes the same gene to be expressed in different forms (isoforms). See Carter, R.W., Splicing and dicing the human genome: Scientists begin to unravel the splicing code 1 July 2010. Return to text.
- Note that unlike ice crystals, where the structure results from the properties of the water molecule, the order of DNA (which codes for the amino acid order in proteins) is not dependant on the chemical properties of its component nucleotides. See also Tampier, M., The treasures of the snow: Do pretty crystals prove that organization can arise spontaneously? Creation 32(2):33–35, 2010. Return to text.
- Human proteins are on average 375 amino acids long, bacteria proteins are on average 267 amino acids long. Note that bacteria and humans have proteins that are much shorter and much larger: book.bionumbers.org/how-big-is-the-average-protein/ Return to text.
- Blanco, F. et al., Exploring the conformational properties of the sequence space between two proteins with different folds: an experimental study, J. Molecular Biology 285(2):741–753, 1999 Return to text.
- Axe, D., Estimating the prevalence of protein sequences adopting functional enzyme folds, Journal of Molecular Biology, 341(5):1295–315, 2004 Return to text.
- This is extraordinarily generous to abiogenesis because amino acids are able to bond in many locations by many kinds of chemical bonds. In living cells, control systems involving enzymes ensure peptide bonds occur in the correct places. Return to text.
- John I. Glass, Nacyra Assad-Garcia, Nina Alperovich, Shibu Yooseph, Matthew R. Lewis, Mahir Maruf, Clyde A. Hutchison III, Hamilton O. Smith, and J. Craig Venter, Essential genes of a minimal bacterium, PNAS 103(2):425–430, 2006 | doi:10.1073/pnas.0510013103. Return to text.
- Lane, N., Was our oldest ancestor a proton-powered rock? New Scientist 204(2370):38–42,2009 http://www.esalq.usp.br/lepse/imgs/conteudo_thumb/Was-our-oldest-ancestor-a-proton.pdf Return to text.
- Popper, K.R., 1974. Scientific Reduction and the Essential Incompleteness of All Science. In Ayala, F. and Dobzhansky, T., eds., Studies in the Philosophy of Biology, University of California Press, Berkeley, p. 270. Return to text.
- Sir Fred Hoyle, as quoted by Lee Elliot Major, “Big enough to bury Darwin”. Guardian (UK) education supplement, 23 Aug 2001; education.guardian.co.uk/higher/physicalscience/story/0,9836,541468,00.html Return to text.
- Elbert Branscomb & Michael Russell, “Frankenstein or a Submarine Alkaline vent: Who is responsible for Abiogenesis?: Part 2: As Life Is Now, so it Must Have Been in the Beginning,” Bioessays 40(8): e1700182 Return to text.
- Yockey, H., Information Theory and Molecular Biology, Cambridge University Press, 1992, p. 284. Return to text.
- Yockey, H, Ref 24, pp. 336. Return to text.