That’s interesting. The main difference seems to be that those other tiny organisms only encode how to produce some metabolic products for the host but cannot reproduce independently, so they are quite close to being organelles. Instead, this new one pretty much only produces the proteins it needs to reproduce and nothing for the host.
The new one with 238 kbp:
> Sukunaarchaeum encodes the barest minimum of proteins for its own replication, and that’s about all. Most strangely, its genome is missing any hints of the genes required to process and build molecules, outside of those needed to reproduce.
Referencing the 159 kbp one:
> However, these and other super-small bacteria have metabolic genes to produce nutrients, such as amino acids and vitamins, for their hosts. Instead, their genome has cast off much of their ability to reproduce on their own.
Still far, far too complex to occur "randomly," which is fascinating. The odds of 112k bases arranging in any meaningful way by chance within a membrane are the kind of thing you wouldn't get if you ran a trillion trillion trillion universes.
There's many hypotheses, basically all different variations on "soup of organic compounds forming complex catalytic cycles that eventually result in the soup producing more similar soup, at which point it begins to be subject to differential selection." It's a reasonable idea but where did this happen, and do the conditions still exist? If we went to that place would it still be happening?
There's reason to believe the answer would be no because modern lifeforms would probably find this goo nutritious. So life may have chemically pulled up the ladder from itself once it formed.
This of course assumes no to more fanciful options: panspermia that pushes the origin back to the beginning of the cosmos and gives you more billions of years, creation by a God or some other kind of supernatural or extra-dimensional entity, etc.
1. Autocatalytic RNA reaction networks -- "soup producing more soup" -- are easily replicated in the lab, subject to Darwinean processes, and are at the center of ongoing study. "0 to Darwin" is now easy, "Darwin to Life" is the new focus, and God of the Gaps must retreat once again.
2. Spores hitchhiking on impact ejecta sounds exotic until you realize that anywhere life is present at all spores will be everywhere and extremely sturdy. That desktop wallpaper you have of planets crashing together and kicking off an epic debris cloud? Everything not molten is full of spores.
3. Religious explanations are not in the same universe of seriousness as 1 and 2. Opening with a religious talking point and closing with a false equivalence is mega sus.
Panspermia is pretty much irrelevant to the actual question though; even assuming life got to Earth the hitchhiker way, it would have to have developed on another planet, and we’re back to square one.
Panspermia is kind of weird to think about IMHO. Because, it likely took a long time to develop and a long time to travel here. So it must have started a long time ago. Before the Solar system was created. But Sol is pretty old. How early could life have started really?
That gets into astrobiology. Theoretically life could have started as soon as its basic ingredients were ready. So not until things had cooled down a bit after the Bang, when there were heavier elements than hydrogen and helium; and some kind of land and water.
> In the redshift range 100 . (1 + z) . 137, the cosmic microwave background (CMB) had a temperature of 273–373 K (0-100◦C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star.
> In the standard ΛCDM cosmology, the first star-forming
halos within our Hubble volume started collapsing at these redshifts,allowing the chemistry of life to possibly begin when the Universe was merely 10–17 million years old.
In comparison, our beloved sun is estimated to have been born 9.2 billion years after the Big Bang, a third of the way into the universe's history so far.
> The Sun is approximately 4.6 billion years old, while the age of the universe, based on current estimates, is about 13.8 billion years.
So our solar system is not that old, relatively speaking. We're among elders, some stars are three times older than the sun.
> In the future, however, life might continue to emerge on planets orbiting dwarf stars, like our nearest neighbor, Proxima Centauri, which will endure hundreds of times longer than the sun’s.
> Ultimately, it would be desirable for humanity to relocate to a habitable planet around a dwarf star like Proxima Centauri b, where it could keep itself warm near a natural nuclear furnace for up to 10 trillion years into the future.
The earliest galaxies formed when the universe was just a few hundred million years old, which means there may have been planets that are 3x times older than Earth.
Several caveats apply, chiefly that heavy elements weren't produced for a while in significant quantity, but were produced fairly early on due to large stars exploding relatively quickly, when they were merely tens of millions of years old, if that.
Not to mention the constant trickle of "X survived in space" stories that we get every time someone bothers to collect and culture a sample. The amount of success at every stage with, frankly, very little effort spent tuning the conditions, multiplied by "bacteria are everywhere" makes hitchhiking less crazy than it sounds. Our intuition misleads us because bacteria are so much better at handling acceleration (easy if you're small) and dessiccation (everywhere is a desert if you're small) than anything we are used to thinking about.
An upper bound probability for the RNA world hypothesis is 10^-1018. A reasonable interpretation is that the RNA world hypothesis is impossible in the real world.
A superficial reading doesn't inspire much confidence in this peer-reviewed article but I agree that RNA-world is a thought experiment at best. There is no evidence of these RNA structures in actual lifeforms.
RNA encodes proteins.
The most parsimonious explanation is that proteins(likely incapable of true replication by themselves) preceded RNA even if an RNA-based system can be designed in theory.
I won't make claims of probability of unknown processes but proteins exist that can assemble spare nucleotides and proteins exist that can assemble proteins out of nucleotide chains.
All you need is a pair of them to come in the vicinity of each other and wait until RNA comes along that encodes a similar-enough pair.
Good news: the primordial oceans were so vast (literally planet-scale) and persisted for so long (millions to billions of years) that you can run a trillion trillion individual random reactions.
You are being severely restricted by your imagination. You seem to have presupposed that random abiogenesis is impossible and reconstructed the facts to support that claim because you can't conceive of the alternative.
Planets are really, really big. Any one chemical reaction is on the scale of molecules. If you let those figures compound for a long time, the number of total reactions gets very, very large. Far larger than you imagine. Many times more.
The probability space of a 140-nucleotide chain is 10^84. The estimated number of atoms in the universe is 10^80. The hypothesized RNA self-replicator is far simpler than the 238,000 base pair archaeal genome. But how are they formed? Even the most favorable prebiotic lab conditions have only produced short nucleotide chains. Direct chemical synthesis only recently achieved chains over 1700 nucleotides long [1].
To go through all 10^84 possible combinations in a billion years, around 10^67 combinations would have to be "tried" per second. So yeah, it doesn't seem feasible to have one and only correct combination of 140 nucleotides spontaneously appear.
But if the "solution" could be composed of a couple of separate smaller parts, that would be stable and linger for a long time, it would be much easier. 40 nucleotides have 10^24 combinations, so only 10^7 tries per second would be needed... over a billion years. And all of the necessary parts would need to be created and then meet in the same place and somehow combine. So, still not easy, but this case doesn't sound so outrageously improbable.
In the end, maybe it is extremely improbable for life to happen, and only one in 10^n suitable planets develops life, and Earth was just very lucky to experience this peculiar phenomenon.
Still the wrong question. Life didn't start by brute-forcing the combinatorial cliff of RNA. I'm a fan of metabolism-first, or membrane-first. It was almost certainly thermodynamically favored the whole way.
>Still far, far too complex to occur "randomly," which is fascinating
I don't see the word "random" anywhere in the article. By random maybe you mean it's seemingly indeterministic? Regardless of the nature of the underlying process, at the classical level, the environment acts as a deterministic filter, ie, other chemical processes.
If you’re interested in this area I highly recommend “The Vital Question” by Nick Lane if you haven’t read it.
The TLDR of his theory is that life originated in alkaline hydrothermal vents on the ocean floor, where natural energy gradients could have driven primitive metabolic reactions before the development of DNA.
Book goes into a lot of layperson-accessible detail.
> Still far, far too complex to occur "randomly," which is fascinating
Why spend time making this point? Nobody believes that this occurred randomly: it occurred via evolution.
The mutations are a random part of evolution, but the process overall is not random at all - no more so than your immune system (which randomly generates antibodies, then selects against those that target innate epitopes), or stable diffusion (which starts with random noise, then marches up a gradient toward a known target).
It is the selection step that makes similar processes non-random, because a random selection step would just be noise.
This is technically random. The entire creationist argument is that complexity cannot come from randomness but evolution is the method in which it does.
Evolution is just a sort of way for low entropy structures to form from randomness. It’s still random all the way down.
The man is just trying to reconcile a belief in god with the scientific reality. He needs to bend the evidence to fit his identity he cannot bend his identity to fit the evidence because that could break his identity. The fact he commented here on this topic is sort of unhinged. It seems like the article presented evidence that is strikingly against his world view and he needed to justify something in order to prevent his identity from rearranging itself according to external reality.
Look, the leap from
“a human in a lab coat mixed some chemicals and got something that grows and divides”
to
“therefore no God (or no transcendent intelligence) is necessary for life to exist”
is not a valid inference. It is a category error dressed up as science.
Demonstrating that intelligence can produce life (or a lifelike system) is the opposite of demonstrating that intelligence is not required. It is literally evidence in favor of the design hypothesis, not against it. The only thing it would rule out is a very narrow version of young-earth creationism that says “God would never let any natural process produce life under any circumstance”.
Also, scaling from “possible on a planet” to “therefore no intelligence was required anywhere in the process” is still the same non sequitur, moving the (apparent) design from the origin of the first cell to the origin of the cosmic initial conditions and laws that permit planetary abiogenesis.
This equation of “intelligent design = creationism = Adam and Eve” is a cultural artifact of the American culture wars, not a reflection of logic or the global scientific community.
>Look, the leap from “a human in a lab coat mixed some chemicals and got something that grows and divides” to “therefore no God (or no transcendent intelligence) is necessary for life to exist”
That is not my chain of reasoning, nor has lab created life has ever been created. So what you're saying can never be used as valid proof of creationism. And I certainly did not use that evidence to make such a claim. Additionally I never said god does exist or does not exist.
"It's all random all the way down" is just another religious belief. Besides, has anyone estimated the probability of creating organisms so complex using this random evolution scheme? Another problem is why would randomly-evolved organisms be so geometrically symmetric? I'd expect a random process to create an unholy blob of matter.
You're lacking imagination and understanding of how these systems form. Symmetry is very commonplace in nature, for very unsurprising reasons, because what's random is how the processes that create those forms change over time, not the entirety of those processes themselves. And yes, there is a huge amount of study of how life could form in the kinds of environments we think existed on earth near the start of life. ATM it's not so much 'how could this happen at all' and more 'what looks like the most likely way that it happened'.
It's not. It's derived from real time observation, logical induction and other historical evidence that's inline with logic and observation. See my other reply to a sibling commenter of yours.
The entire fossil record and the mountains of shared DNA between very different creatures is pretty compelling evidence. Not to mention the idea of changing 'kinds' is an entirely human-derived categorisation, not something that has some natural definition.
Easy. Covid evolved forms. The genes are different. There are measurable differences in DNA. These are slight.
So from real time observation we know viruses and bacteria can mutate and have small delta changes in their DNA.
From this we can deduce that over long period of time many small changes can equate to big changes in DNA.
Because we know DNA describes macro characteristics of all living beings and effects behavior, physicality and speciation by logic we know that through induction many many small changes together equals big change and thus evolution can result in speciation and different creatures.
This is the literal conclusion through Direct observation and the inescapable logic of induction. Not to mention it's inline with fossil evidence AND covid is clearly not the only species where we observe mutations. Mutations are observed everywhere, including humans. Cancer is mutation and selection as well.
Doesn't have to be convincing to you. It's a fact and inescapable conclusion. If you're not convinced, you're wrong.
If mutations can happen, then by logic many mutations can happen, if many mutations can happen then many many mutations can stack up and cause speciation. By believing in mutations, evolution follows via logical induction.
Your DNA can be edited with many many mutations until it becomes indistinguishable from penguin DNA. Take that DNA and insert it into an zygote embryo and you get a penguin, not a human.
This is not a conclusion formed by observation. This is basic logic, 1 + 1 = 2. If the axiom is mutation, evolution is the logical theorem that follows. It is undeniable.
You have to go through a lot of mental gymnastics to deny this logic, but it's worth it if such mental gymnastics formulates a conclusion that remains inline with your religious identity. People without this bias who don't have truth tied to their identity don't need to do this kind of thing.
"Change kinds" is something that only people who believe in a rather literal view of the Christian bible say, and only because that's the popular fundamentalist argument against evolution.
Fundamentally, it's impossible to reconstruct something from the fossil record that's convincing to these folks, because they will always arbitrarily decide "fossil 1 is kind X, and fossil 2 is kind Y, you need to find me fossil 1.5," no matter how close in time and likeness the fossils are.
So what they actually want is "evolve a lizard species into cats" which fundamentally misrepresents both A) how evolution works (it does not concern itself with human categories) and B) the vast timescale over which small changes accrue.
"Kinds" are just human categories we've mapped onto the results of billions of years of evolution after the fact.
The point I was making was that the complexity curve has to meet the floor at some point, and thinking about how this happens and what that looks like is interesting.
I was familiar with RNA world but wasn't aware of how much progress had been made.
Unfortunately your comment is mostly indistinguishable from the kind of "just asking questions" thing actual creationists occasionally post. And you did draw in at least one actual creationist in your replies. Sorry dude. :D Anyway, as a couple of us mentioned, be sure to check out Nick Lane's theories.
Isn't replication the single most important act of metabolism for an organism? I am trying to reconcile their ""lost genes include those central to cell metabolism, meaning it can neither process nutrients nor grow on its own" with their "The organism’s “replicative core” — the genetic components needed to reproduce itself — remains, making up more than half of its genome".
Replication (making DNA, RNA, and proteins, and ultimately dividing) is a highly energy-intensive and material-intensive process. What appears to be lost by Sukunaarchaeum are the genes to build basic building blocks (amino acids, vitamins, nucleotides) from scratch. It cannot find a sugar molecule and break it down for energy (it can "neither process nutrients nor grow on its own"). Yet it can take pre-made energy and building blocks and assemble them into a new organism.
What is the exact line between the host's metabolic contribution and the archaeon's replicative assembly? How "finished" are the raw materials that the host provides, and how does the archaeon's extremely reduced genome still manage the subsequent steps of self-replication?
You could argue the same way for a lot of parasite species, many of which are ridiculously more complex. Is a complex multicellular organism (an animal even) not alive because it needs to get some component needed for its reproduction from another species? If you get hung on such specific components, where do you draw the line?
So in this sense then, human beings themselves are obligate metabolic parasites on the planetary ecosystem, particularly on other life forms (plants, animals, microbes). The term "parasite" here is used in the metabolic sense of relying on another organism to produce essential compounds one cannot produce oneself. The molecules we must obtain fully synthesized from our diet are called essential nutrients. And for a Sukunaarchaeum, everything is an essential nutrient.
Are there any animals which don’t need components from another organism? Isn’t heterotrophy one of the notable attributes of Animalia? There are the infamous sea slugs which eat algae then use the algae’s photosynthetic chloroplasts to photosynthesize the chemical energy they need, but they still need the algae to make those chloroplasts.
Interesting to realize that all animals are parasites (or perhaps symbiotes in some rare cases?) when you zoom out and look at the big picture. Almost makes me feel a bit guilty for not being a self-sustaining plant.
As I understand it, it's not so much that they got "hung up" on some specific capabilities for theoretical reasons, but that it's rare to find cells without these capabilities. In other words, it's nature that seemed so "hung up" on these things.
You could make a distinction here in that we only need raw materials, we don't need another organism to reproduce. Mosquitos can also easily consume raw materials in the form of nectar to survive, but they need to take blood from other animals if they want to reproduce. If you go along this chain of thought, you can come up with arbitrary definitions.
They are technically no longer individual life forms. They sure used to be, but we merged quite some time ago. Of course that opens a whole other can of worms with respect to who you really are. You're trillions of microorganisms living together and quite a few of them don't even share your DNA.
We need 20 different amino acids to build all our proteins. We can synthesize 11 of them (non-essential amino acids), but we must obtain the other 9 Essential Amino Acids fully formed from the food we eat.
I wonder if this minimal cell could be described instead as something between a bacteria and a virus. I am not a biologist, but IIRC viruses penetrate cells then hijack the cell's standard machinery to replicate itself, until the cell explodes; sort of like a DNA/RNA injection exploit.
For all the folks saying, "Isn't this just a virus?"
The actual paper states that the genome encodes transfer RNA's and ribosomal RNA's. I think that's a really important biological distinction missing from the popular press junket. The primary source material is well written and elucidates a lot more than the Quanta article. https://www.biorxiv.org/content/10.1101/2025.05.02.651781v1
> the bacterium Carsonella ruddii, which lives as a symbiont within the guts of sap-feeding insects, has an even smaller genome than Sukunaarchaeum, at around 159,000 base pairs
159 000 base pairs is ~320 Kbit, or 40 KBytes. I wonder, if that is the minimum size of a cell firmware. Also, if the cell is that simple, can we study it exhaustively and completely? Like, decipher every base pair in DNA, and determine what it is responsible for. And make an interactive website for that.
Reminds me of how the discovery of giant viruses - like truly huge viral particles - was immediately also followed by discovering "virophages" which parasitized them.
Which of course makes sense to some degree: if an adaptive strategy is successful enough, then parasitizing something which successfully implements it is going to be resource favorable (and likely, presumably by being a member of that species and just shedding components you don't need if you take them).
> ... we report the discovery of Candidatus Sukunaarchaeum mirabile, a novel archaeon with an unprecedentedly small genome of only 238 kbp —less than half the size of the smallest previously known archaeal genome— from a dinoflagellate-associated microbial community.
What is this, some content creator run Biohacker Lab in some basement on Microflix premises?
Ominous voice: the tiny cell withdrew into the cracks of existence and saved it's entire code to be in the lines between, the Singular Point which was neither a fraction of space, nor a unit of time, hidden in the void of Chututululu's (33rd degree cousin of Cthulhu) dreams, written in the unspeakable language of the subtext of the book of neither life nor death, that nobody would decipher until the time was right AND GODZILLA GETS TO WALK THE EARTH AGAIN.
Life's two most fundamental properties are homeostasis and reproduction. The loss of these two combined with its parasitic nature makes this cell a form on non-life.
You're being rigid about your preferred definition of life, but for what purpose? What is gained by categorizing this as strictly non-living?
Wikipedia on the definition of life:
> Since there is no consensus for a definition of life, most current definitions in biology are descriptive. Life is considered a characteristic of something that preserves, furthers or reinforces its existence in the given environment. This implies all or most of the following traits: [list of seven common traits of life]
> Life's two most fundamental properties are homeostasis and reproduction.
> The loss of these two combined with its parasitic nature makes this cell a form on non-life.
This is a decidedly Eukaryote-centric take. Homeostasis in higher mammals is a complex network of genes -> RNA -> proteins -> metabolic pathways
Reproduction is also far more simple in organisms with binary fission cellular division.
A more appropriate scientific term would be obligate commensalism vs. "parasitic". That actually encapsulates their need for metabolic precursors from the host, but allows for tRNA, rRNA, origin of replication, etc...present in the organism's genome.
No life exists "by themselves". Self-replication means using only its own DNA and not mangling with other's. Virii are not only parasites but dead matter (a ribonucl molecule surrounded by proteins that happens to stick to other cells, like dirt on the skin). Gut microbioma is parasite.
There is another life property that this object does not fulfill and is called Teleonomia, that is governed by an ultimate goal.
First, context: a "life/not-life" distinction is far more "science" than science - widespread in "science" education, but rarely comes up in science research. (Might be interesting to create a list of similar?) Why the emphasis there... I don't know - perhaps because we teach by memorizing definitions and lists, not by learning design spaces and their landmarks? Or at least by giving exemplars without characterizing variance.
One of the few places I've seen it come up in science, was ecosystem multi-scale simulation software. Where virus was squarely in the heritable characteristics under selection pressure ("life") bucket, rather than abiotic or biogenic.
Informal "do you think of viruses as alive?" seems to vary by field. I've seen a marine bio labs be overwhelmingly yes. I've been told medical immunology leans no. But it seems more social-media engagement question than research question or synthesis.
Not sure why you linked that particular article, as it does not mention anywhere whether viruses are alive (though it implies they're alive with the sentence "Vaccines may consist of either live or killed viruses").
They are infectious agents, but many life forms are infectious agents.
That article (and the more general article on viruses) both pointedly avoid referring to viruses as organisms, "any living thing that functions as an individual".
Which specifically addresses edge cases including viruses, which "are not typically considered to be organisms, because they are incapable of autonomous reproduction, growth, metabolism, or homeostasis".
The terms "live" and "killed" have historical origins, but would better be read as "active" or "deactivated", and the immediately succeeding sentence clarifies this: "Live vaccines contain weakened forms of the virus, but these vaccines can be dangerous when given to people with weak immunity."
And yes, there are infectious agents which also happen to be organisms, such as bacteria, amoebas, funguses, etc. Tuberculosis (Mycobacterium tuberculosis), many stomach ulcers (Helicobacter pylori), botulism (Clostridium botulinum), and e. coli poisoning (Escherichia coli) are all infectious disease caused by bacteria. Giardiasis is a G-I infection of the Giardia amoeba. There are numerous fungal infections (many UTI infections, athlete's foot, jock itch, nail infections).
Further down the non-life infectious agent chain are prion diseases such as Transmissible spongiform encephalopathy ("mad cow" disease in cattle, "Creutzfeldt–Jakob disease", amongst others). These are literally misfolded proteins, which lack not only metabolism but any genetic material (DNA, RNA), but still propagate.
You misunderstood me. I wasn't claiming viruses are or aren't alive. I was pointing out you chose a citation that doesn't contain support for your claim. There are plenty of sources that would back you up, but that link doesn't.
> That article (and the more general article on viruses) both pointedly avoid referring to viruses as organisms
As if you expect people to carefully read the whole article, notice it doesn't mention anywhere whether viruses are alive, and conclude that by not mentioning this it supports your claim. By the same logic, it pointedly avoids saying viruses aren't alive.
> Scientific opinions differ on whether viruses are a form of life or organic structures that interact with living organisms. They have been described as "organisms at the edge of life", since they resemble organisms in that they possess genes, evolve by natural selection, and reproduce by creating multiple copies of themselves through self-assembly. Although they have genes, they do not have a cellular structure, which is often seen as the basic unit of life. Viruses do not have their own metabolism and require a host cell to make new products. They therefore cannot naturally reproduce outside a host cell—although some bacteria such as rickettsia and chlamydia are considered living organisms despite the same limitation. Accepted forms of life use cell division to reproduce, whereas viruses spontaneously assemble within cells. They differ from autonomous growth of crystals as they inherit genetic mutations while being subject to natural selection. Virus self-assembly within host cells has implications for the study of the origin of life, as it lends further credence to the hypothesis that life could have started as self-assembling organic molecules. The virocell model first proposed by Patrick Forterre considers the infected cell to be the "living form" of viruses and that virus particles (virions) are analogous to spores. Although the living versus non-living debate continues, the virocell model has gained some acceptance.
ok, i get that, and now is a bacteria considered more agentic than a virus then ? (that's a bit of a side-question sorry). bacterias at least reproduce on their own so they check all the boxes.
So... where does it get its ATP? The article says it's lacking pretty much all metabolism -- does that include cellular respiration and/or fermentation? Does it just get its ATP all from its host, or does it make some itself and get some from its host, or what?
I think the genome might be mostly just the "config file". So the cell already contains most of the information and mechanisms needed for the organism. The genome is config flags and some more detailed settings that turn things on and off in the cell, at specific times in the life of the organism. From this point of view, the discussion about how many pairs/bytes of information are in the genome is misleading. Similar analogy: I can write a hello world program, which displays hello world on the screen. But the screen is 4k, the windows background is also visible, so the hardware and OS are 6-8 orders of magnitude more complex than the puny program, and the output is then much more complex than the puny program.
Virus are simpler and have challenged the definition of life for a long time already. This article excludes virus from life because they lack ribosomes.
Last time I checked, they are considered "not alive" when outside of a host, and "alive" when inside a host.
About size:
"Genome size varies greatly between species. The smallest—the ssDNA circoviruses, family Circoviridae—code for only two proteins and have a genome size of only two kilobases;[61] the largest—the pandoraviruses—have genome sizes of around two megabases which code for about 2500 proteins"
The definition of life is also uninteresting. At its core it is just a vocabulary and classification issue. We humans invented the word life and we humans chose to make the word vague, confusing and differently defined among different people. An arbitrary vocabulary and definitional choice for a word “life” is not in actuality interesting to think about.
Yet people get hung up about it as if it’s a philosophical problem. It is not a philosophy problem. The word is loaded and you’re simply spending an inordinate amount of time trying to define some made up boundary of what fits this category you made up. It is a communication problem disguised as deeper.
It is a question in philosophy. It is the difference between being considered a conscious being, and not. Since for now our definitions of a conscious being is tied to being alive (when is a human alive and not death?). So obviously it has implications on ontological questions. It fundamentally limits our understanding of what exists and just as important, why we exist.
That's an interesting definition, but it does have some issues.
Is an infertile animal (which can't reproduce) dead? What about a nerve cell (which have differentiated too far to become a reproductive cell)? Or a red blood cell (which has no genome)?
From the other end, is a genetic algorithm alive? What about a manuscript? Manuscripts are copied (so they reproduce), and have frequent copying errors, which propagate.
Atoms and sub-atomic particles fit this definition.
Machines fit this definition.
Fire fits this definition.
Truth is "life" is not a distinct category. We just think of life as complex life. A complex system that mines energy gradients to preserve and replicate its forms.
But there's no hard boundary. It's just in our head.
People always come up with people-centric definitions. They need to be updated based on what are the fundamental characteristic of something that is alive.
The current, more standard definition, seems to be based on metabolism. I disagree and argue for reproduction and evolution.
Reproduction in time and reproduction in space are connected. If atoms couldn't reproduce (I can sense most readers knee-jerking reading this), they'd be all unique, wouldn't they. And yet they aren't.
You could say "they have no heritability", and not the way you expect, I guess, but they all inherit the same local laws of physics, and they may even impact those laws, thus forming a feedback loop, and clearly there are googols of them in clusters, same weight, same energy, same polarity, same properties, same states, much like you see with any other species in nature, in fact in far lesser numbers.
If robots are made in a factory, does this count as reproduction? If not, why not. Does a mother's womb not resemble a "baby factory". A baby does not create itself. Always something else creates you.
We have clusters of "common sense" about these things, and most of what I said immediately sounds stupid to "common sense". Yet common sense falls apart if you start thinking about it. But Internet is not EXACTLY conductive to "thinking about it". It's all about the hot takes and the current consensus. Then time passes, and that consensus seems truly unenlightened.
I’ve been thinking about a wild theory regarding the incredible biological complexity we see in mammals today.
What if our bodies (apart from the brain) are actually the result of an ancient aggregation of once-separate "organisms" that evolved to live symbiotically?
Over millions of years, their DNA might have fused and co-evolved into a single, unified genome. What began as cooperation between distinct life forms could have gradually become inseparable, giving rise to the intricate multicellular systems we now take for granted.
It's called Symbiogenesis [0] and it's not at all a wild theory. But it's limited to cell components, not multiples organs fusing to create something as complex as a mammal.
This isn't a wild theory or a novel one. It's well-established that endogenous retroviruses alter DNA and are inherited. In addition to the primary genome being modified this way, all mitochondria are symbiotic organisms inside plant and animal cells, with their own DNA, and are vital to life. Same thing for chloroplasts in plants. And then there are gut bacteria, which are vital to life, symbiotic, and directly influence evolution and the genome.
Also, as others have noted, your idea is not necessarily wild. Certainly, at the sub-cellular level, there is tremendous evidence that symbiosis played a part in creating "higher level" organisms (i.e., eukaryotes).
Many genomes are like a junk-yard with fossilized relics of infectious agent nucleic acid (e.g., viruses), etc. Apologies for the junk-yard / fossil mixed metaphor.
I believe that we’re living in that situation now. I don’t think life can be divided into smaller organisms. That there is just one complex life that we failed to see based on our past prejudice.
This is cool but doesn't say much about the definition of life IMO. They're obligate parasites. This isn't a new category. They're still eating stuff from their host (probably, given the caveat later in the article), and still using it to replicate, it's just a more limited diet.
They aren’t. Apart from DNA replication, transcription, and translation, their genome lacks elements encoding for even the most simple metabolic pathways.
Then where are they getting the materials to replicate? Where are they getting the energy? Magic? No, they're pulling pre-metabolized materials and energy from the host.
I don’t think a precise definition of life is particularly important or of particular interest to most biologists. This thing is life in the sense that it’s definitely in scope of being studied by biologists (same is true for viruses, of course). And the reason it is speculated that it may be crucial to understanding life is mentioned in the article: “This organism might be a fascinating living fossil—an evolutionary waypoint that managed to hang on.”
I don't think that they are. The term life, as it's currently defined, is not very useful. The reality is that there is a very colorful spectrum of microscopic biology and that a single bin of "alive" and "not alive" is like trying to paint the mona lisa with a single pixel.
This scishow video gives a good look at the tip of the iceberg.
An interesting counterpoint to how little we know, and/or how useless in practical terms our quantum level understanding of physics is, is chemistry.
Chemistry is adjacent to physics, at least classical physics and the standard model, so you might think that we should be able to use our knowledge of physics to determine things like atomic bond "angles" and the protein folding problem, yet even this smallish step up in abstraction from physics puts us in a realm where we know very little. DeepMind's AlphaFold, now able to correctly predict 90% of protein folding in agreement with experimental determination, is mostly based on learning from experimental data, as well as evolutionary consideration of proteins that co-evolved, etc.
It makes you wonder how useful the reductionist model really is in terms of understanding higher level dynamics. Maybe different levels of abstraction like physics, chemistry, etc, are really a lot more independent than is commonly thought.
Maybe better to say "We understand enough physics to model all the possible interactions PHYSICS might have on this planet".
There are many levels of abstraction between quantum/particle physics and life, or even just cosmology (things like dark matter, etc), that we really know very little about.
You misunderstood my original statement. SCOTUS struck down RvsW, which I think is wrong- both morally and scientifically. You shouldn't name call, leave me alone or I will report you.
> Its easily googlable or ChatGPT-able. Dont be intentionally dense. You are just making your "side" look dumb.
This is an unacceptable comment on HN. It breaks several guidelines, including those listed below. Please read the guidelines and make an effort to observe them whenever participating here. We've had to ask this of you multiple times previously.
Be kind. Don't be snarky. Converse curiously; don't cross-examine. Edit out swipes.
Comments should get more thoughtful and substantive, not less, as a topic gets more divisive.
When disagreeing, please reply to the argument instead of calling names. "That is idiotic; 1 + 1 is 2, not 3" can be shortened to "1 + 1 is 2, not 3."
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Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something.
Only if it has a mechanism to send signals into the host and cell. For the CEO metaphor to hold, I'll accept that these signals can be entirely ignored, but they need to be transmitted.
What do you mean? The interaction described in the article is just of the small cell stealing nutrients from the host's pouch. That seems like enough of a "point" for the parasitic cell, while giving it zero incentive to advertise its presence with signals.
Life is the process of decreasing entropy. If they stick with that definition, they’d be fine. And they’d find out that life is even more abundant than they can imagine.
This is one of those things that sounds profound, but only until you think about it. Depending on how you read this, it either excludes life entirely or includes all sorts of things that are not meaningfully alive.
1. Living things locally decrease entropy but globally increase it.
2. Many other processes do the same. As chermi noted, a liquid solidifying has the same characteristic.
I definitely choose the second of your two outcomes. That it includes all sorts of things that you think are not meaningfully alive. But these things are actually life.
Yes, living things locally decrease entropy and that’s my point.
And maybe I should’ve been more clear for people who cannot grasp new understandings, anything that can decrease its own entropy is living.
I mean, do you think life has nothing to do with the organization matter into a lower entropy state?
Water does not decrease its own entropy. If you can’t understand the distinction I’m making then you do not have the imagination and creativity to create new understanding.
A glass of water in a cold environment radiates away heat until it freezes, decreasing its local entropy and increasing global entropy.
> If you can’t understand the distinction I’m making then you do not have the imagination and creativity to create new understanding.
Perhaps you could explain your distinction instead of insulting people. It’s possible you have some interesting and insightful distinction but as of now you’ve not explained it nor given any examples of this “more abundant” life.
I’m not insulting you. I’m pointing out a reality. You’re reading comprehension is failing you right now.
Water does not freeze itself. That is the distinction. But myself, as a living being, can turn water into ice. And I can create an organize materials inside of my own body.
I pointed out something interesting. The least thing you could do is actually look up to see if there’s any validity or research on what I’m talking about.
By more abundant life, I’m talking about how the definition of life we have is limited, but it’s ever expanding based on the papers of the original post. I’m talking about a greater expansion of our understanding of life that’s discussed in papers that deal with entropy and life.
At least own it. Saying someone lacks imagination and creativity and now reading comprehension is absolutely insulting.
> I pointed out something interesting. The least thing you could do is actually look up to see if there’s any validity or research on what I’m talking about.
I can’t look up anything based on your vague comment. That’s why I asked what you mean.
> Saying someone lacks imagination and creativity and now reading comprehension is absolutely insulting.
I said: "You’re reading comprehension is failing you right now." The "right now" part menas that I am not saying it does not exist, just that they are not understanding what is written.
Why is it an insult to say someone lacks creativity? It was objectively true to me and it is not an insult, just a truth. Like if someone has red hair. At worst it was my opinion.
You know what an insult is? To take what I said to think that I meant that water turning to ice was life.
Very impressive! To be clear, this is not the smallest known bacterial genome; only the smallest known archaeal bacterial genome, at 238k base pairs.
In the article they mention C. ruddii, with a smaller 159k base pair genome.
But according to wikipedia, it seems N. deltocephalinicola, at 112k base pairs, may be the smallest known bacterial genome. https://en.wikipedia.org/wiki/Nasuia_deltocephalinicola
That’s interesting. The main difference seems to be that those other tiny organisms only encode how to produce some metabolic products for the host but cannot reproduce independently, so they are quite close to being organelles. Instead, this new one pretty much only produces the proteins it needs to reproduce and nothing for the host.
The new one with 238 kbp:
> Sukunaarchaeum encodes the barest minimum of proteins for its own replication, and that’s about all. Most strangely, its genome is missing any hints of the genes required to process and build molecules, outside of those needed to reproduce.
Referencing the 159 kbp one:
> However, these and other super-small bacteria have metabolic genes to produce nutrients, such as amino acids and vitamins, for their hosts. Instead, their genome has cast off much of their ability to reproduce on their own.
A nitpick: Although similar in some aspects, archaea are not bacteria; they are classified under their own phylogenetic domain.
Still far, far too complex to occur "randomly," which is fascinating. The odds of 112k bases arranging in any meaningful way by chance within a membrane are the kind of thing you wouldn't get if you ran a trillion trillion trillion universes.
There's many hypotheses, basically all different variations on "soup of organic compounds forming complex catalytic cycles that eventually result in the soup producing more similar soup, at which point it begins to be subject to differential selection." It's a reasonable idea but where did this happen, and do the conditions still exist? If we went to that place would it still be happening?
There's reason to believe the answer would be no because modern lifeforms would probably find this goo nutritious. So life may have chemically pulled up the ladder from itself once it formed.
This of course assumes no to more fanciful options: panspermia that pushes the origin back to the beginning of the cosmos and gives you more billions of years, creation by a God or some other kind of supernatural or extra-dimensional entity, etc.
1. Autocatalytic RNA reaction networks -- "soup producing more soup" -- are easily replicated in the lab, subject to Darwinean processes, and are at the center of ongoing study. "0 to Darwin" is now easy, "Darwin to Life" is the new focus, and God of the Gaps must retreat once again.
2. Spores hitchhiking on impact ejecta sounds exotic until you realize that anywhere life is present at all spores will be everywhere and extremely sturdy. That desktop wallpaper you have of planets crashing together and kicking off an epic debris cloud? Everything not molten is full of spores.
3. Religious explanations are not in the same universe of seriousness as 1 and 2. Opening with a religious talking point and closing with a false equivalence is mega sus.
Would love to see some sources for #1. #2 sounds plausible but speculative?
Panspermia is pretty much irrelevant to the actual question though; even assuming life got to Earth the hitchhiker way, it would have to have developed on another planet, and we’re back to square one.
Panspermia is kind of weird to think about IMHO. Because, it likely took a long time to develop and a long time to travel here. So it must have started a long time ago. Before the Solar system was created. But Sol is pretty old. How early could life have started really?
That gets into astrobiology. Theoretically life could have started as soon as its basic ingredients were ready. So not until things had cooled down a bit after the Bang, when there were heavier elements than hydrogen and helium; and some kind of land and water.
> In the redshift range 100 . (1 + z) . 137, the cosmic microwave background (CMB) had a temperature of 273–373 K (0-100◦C), allowing early rocky planets (if any existed) to have liquid water chemistry on their surface and be habitable, irrespective of their distance from a star.
> In the standard ΛCDM cosmology, the first star-forming halos within our Hubble volume started collapsing at these redshifts,allowing the chemistry of life to possibly begin when the Universe was merely 10–17 million years old.
From: The Habitable Epoch of the Early Universe - https://arxiv.org/abs/1312.0613
In comparison, our beloved sun is estimated to have been born 9.2 billion years after the Big Bang, a third of the way into the universe's history so far.
> The Sun is approximately 4.6 billion years old, while the age of the universe, based on current estimates, is about 13.8 billion years.
So our solar system is not that old, relatively speaking. We're among elders, some stars are three times older than the sun.
> In the future, however, life might continue to emerge on planets orbiting dwarf stars, like our nearest neighbor, Proxima Centauri, which will endure hundreds of times longer than the sun’s.
> Ultimately, it would be desirable for humanity to relocate to a habitable planet around a dwarf star like Proxima Centauri b, where it could keep itself warm near a natural nuclear furnace for up to 10 trillion years into the future.
Wild that the background radiation was a balmy room temperature at one point. Never thought about that.
The earliest galaxies formed when the universe was just a few hundred million years old, which means there may have been planets that are 3x times older than Earth.
Several caveats apply, chiefly that heavy elements weren't produced for a while in significant quantity, but were produced fairly early on due to large stars exploding relatively quickly, when they were merely tens of millions of years old, if that.
RNA World is really cooking: https://pubmed.ncbi.nlm.nih.gov/39358873/
Ejection: https://link.springer.com/chapter/10.1007/3-540-25736-5_3
Reentry: https://journals.plos.org/plosone/article?id=10.1371/journal...
Not to mention the constant trickle of "X survived in space" stories that we get every time someone bothers to collect and culture a sample. The amount of success at every stage with, frankly, very little effort spent tuning the conditions, multiplied by "bacteria are everywhere" makes hitchhiking less crazy than it sounds. Our intuition misleads us because bacteria are so much better at handling acceleration (easy if you're small) and dessiccation (everywhere is a desert if you're small) than anything we are used to thinking about.
https://pmc.ncbi.nlm.nih.gov/articles/PMC1892545/
An upper bound probability for the RNA world hypothesis is 10^-1018. A reasonable interpretation is that the RNA world hypothesis is impossible in the real world.
A superficial reading doesn't inspire much confidence in this peer-reviewed article but I agree that RNA-world is a thought experiment at best. There is no evidence of these RNA structures in actual lifeforms. RNA encodes proteins. The most parsimonious explanation is that proteins(likely incapable of true replication by themselves) preceded RNA even if an RNA-based system can be designed in theory. I won't make claims of probability of unknown processes but proteins exist that can assemble spare nucleotides and proteins exist that can assemble proteins out of nucleotide chains. All you need is a pair of them to come in the vicinity of each other and wait until RNA comes along that encodes a similar-enough pair.
The probability of assembling two proteins randomly close by in spatial and temporal terms runs into Chadwick's proximity problem.
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Good news: the primordial oceans were so vast (literally planet-scale) and persisted for so long (millions to billions of years) that you can run a trillion trillion individual random reactions.
You are being severely restricted by your imagination. You seem to have presupposed that random abiogenesis is impossible and reconstructed the facts to support that claim because you can't conceive of the alternative.
Planets are really, really big. Any one chemical reaction is on the scale of molecules. If you let those figures compound for a long time, the number of total reactions gets very, very large. Far larger than you imagine. Many times more.
The probability space of a 140-nucleotide chain is 10^84. The estimated number of atoms in the universe is 10^80. The hypothesized RNA self-replicator is far simpler than the 238,000 base pair archaeal genome. But how are they formed? Even the most favorable prebiotic lab conditions have only produced short nucleotide chains. Direct chemical synthesis only recently achieved chains over 1700 nucleotides long [1].
1. https://www.chemistryworld.com/news/first-direct-chemical-sy...
To go through all 10^84 possible combinations in a billion years, around 10^67 combinations would have to be "tried" per second. So yeah, it doesn't seem feasible to have one and only correct combination of 140 nucleotides spontaneously appear.
But if the "solution" could be composed of a couple of separate smaller parts, that would be stable and linger for a long time, it would be much easier. 40 nucleotides have 10^24 combinations, so only 10^7 tries per second would be needed... over a billion years. And all of the necessary parts would need to be created and then meet in the same place and somehow combine. So, still not easy, but this case doesn't sound so outrageously improbable.
In the end, maybe it is extremely improbable for life to happen, and only one in 10^n suitable planets develops life, and Earth was just very lucky to experience this peculiar phenomenon.
Still the wrong question. Life didn't start by brute-forcing the combinatorial cliff of RNA. I'm a fan of metabolism-first, or membrane-first. It was almost certainly thermodynamically favored the whole way.
>Still far, far too complex to occur "randomly," which is fascinating
I don't see the word "random" anywhere in the article. By random maybe you mean it's seemingly indeterministic? Regardless of the nature of the underlying process, at the classical level, the environment acts as a deterministic filter, ie, other chemical processes.
If you’re interested in this area I highly recommend “The Vital Question” by Nick Lane if you haven’t read it.
The TLDR of his theory is that life originated in alkaline hydrothermal vents on the ocean floor, where natural energy gradients could have driven primitive metabolic reactions before the development of DNA.
Book goes into a lot of layperson-accessible detail.
> Still far, far too complex to occur "randomly," which is fascinating
Why spend time making this point? Nobody believes that this occurred randomly: it occurred via evolution.
The mutations are a random part of evolution, but the process overall is not random at all - no more so than your immune system (which randomly generates antibodies, then selects against those that target innate epitopes), or stable diffusion (which starts with random noise, then marches up a gradient toward a known target).
It is the selection step that makes similar processes non-random, because a random selection step would just be noise.
This is technically random. The entire creationist argument is that complexity cannot come from randomness but evolution is the method in which it does.
Evolution is just a sort of way for low entropy structures to form from randomness. It’s still random all the way down.
The man is just trying to reconcile a belief in god with the scientific reality. He needs to bend the evidence to fit his identity he cannot bend his identity to fit the evidence because that could break his identity. The fact he commented here on this topic is sort of unhinged. It seems like the article presented evidence that is strikingly against his world view and he needed to justify something in order to prevent his identity from rearranging itself according to external reality.
Look, the leap from “a human in a lab coat mixed some chemicals and got something that grows and divides” to “therefore no God (or no transcendent intelligence) is necessary for life to exist”
is not a valid inference. It is a category error dressed up as science.
Demonstrating that intelligence can produce life (or a lifelike system) is the opposite of demonstrating that intelligence is not required. It is literally evidence in favor of the design hypothesis, not against it. The only thing it would rule out is a very narrow version of young-earth creationism that says “God would never let any natural process produce life under any circumstance”.
Also, scaling from “possible on a planet” to “therefore no intelligence was required anywhere in the process” is still the same non sequitur, moving the (apparent) design from the origin of the first cell to the origin of the cosmic initial conditions and laws that permit planetary abiogenesis.
This equation of “intelligent design = creationism = Adam and Eve” is a cultural artifact of the American culture wars, not a reflection of logic or the global scientific community.
>Look, the leap from “a human in a lab coat mixed some chemicals and got something that grows and divides” to “therefore no God (or no transcendent intelligence) is necessary for life to exist”
That is not my chain of reasoning, nor has lab created life has ever been created. So what you're saying can never be used as valid proof of creationism. And I certainly did not use that evidence to make such a claim. Additionally I never said god does exist or does not exist.
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"It's all random all the way down" is just another religious belief. Besides, has anyone estimated the probability of creating organisms so complex using this random evolution scheme? Another problem is why would randomly-evolved organisms be so geometrically symmetric? I'd expect a random process to create an unholy blob of matter.
You're lacking imagination and understanding of how these systems form. Symmetry is very commonplace in nature, for very unsurprising reasons, because what's random is how the processes that create those forms change over time, not the entirety of those processes themselves. And yes, there is a huge amount of study of how life could form in the kinds of environments we think existed on earth near the start of life. ATM it's not so much 'how could this happen at all' and more 'what looks like the most likely way that it happened'.
It's not. It's derived from real time observation, logical induction and other historical evidence that's inline with logic and observation. See my other reply to a sibling commenter of yours.
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The entire fossil record and the mountains of shared DNA between very different creatures is pretty compelling evidence. Not to mention the idea of changing 'kinds' is an entirely human-derived categorisation, not something that has some natural definition.
Easy. Covid evolved forms. The genes are different. There are measurable differences in DNA. These are slight.
So from real time observation we know viruses and bacteria can mutate and have small delta changes in their DNA.
From this we can deduce that over long period of time many small changes can equate to big changes in DNA.
Because we know DNA describes macro characteristics of all living beings and effects behavior, physicality and speciation by logic we know that through induction many many small changes together equals big change and thus evolution can result in speciation and different creatures.
This is the literal conclusion through Direct observation and the inescapable logic of induction. Not to mention it's inline with fossil evidence AND covid is clearly not the only species where we observe mutations. Mutations are observed everywhere, including humans. Cancer is mutation and selection as well.
This isn't convincing to me, I'm not disputing that mutations exist. Do they become different categories of being?
Macro Evolution has always seemed like a philosophy/ideology/religion to me with a veneer of science.
Doesn't have to be convincing to you. It's a fact and inescapable conclusion. If you're not convinced, you're wrong.
If mutations can happen, then by logic many mutations can happen, if many mutations can happen then many many mutations can stack up and cause speciation. By believing in mutations, evolution follows via logical induction.
Your DNA can be edited with many many mutations until it becomes indistinguishable from penguin DNA. Take that DNA and insert it into an zygote embryo and you get a penguin, not a human.
This is not a conclusion formed by observation. This is basic logic, 1 + 1 = 2. If the axiom is mutation, evolution is the logical theorem that follows. It is undeniable.
You have to go through a lot of mental gymnastics to deny this logic, but it's worth it if such mental gymnastics formulates a conclusion that remains inline with your religious identity. People without this bias who don't have truth tied to their identity don't need to do this kind of thing.
"Change kinds" is something that only people who believe in a rather literal view of the Christian bible say, and only because that's the popular fundamentalist argument against evolution.
Fundamentally, it's impossible to reconstruct something from the fossil record that's convincing to these folks, because they will always arbitrarily decide "fossil 1 is kind X, and fossil 2 is kind Y, you need to find me fossil 1.5," no matter how close in time and likeness the fossils are.
So what they actually want is "evolve a lizard species into cats" which fundamentally misrepresents both A) how evolution works (it does not concern itself with human categories) and B) the vast timescale over which small changes accrue.
"Kinds" are just human categories we've mapped onto the results of billions of years of evolution after the fact.
Is there any way to demonstrate it or is it only an unfalsifiable claim that requires unfathomably long timelines?
People misread my comment as creationism.
The point I was making was that the complexity curve has to meet the floor at some point, and thinking about how this happens and what that looks like is interesting.
I was familiar with RNA world but wasn't aware of how much progress had been made.
Unfortunately your comment is mostly indistinguishable from the kind of "just asking questions" thing actual creationists occasionally post. And you did draw in at least one actual creationist in your replies. Sorry dude. :D Anyway, as a couple of us mentioned, be sure to check out Nick Lane's theories.
Isn't replication the single most important act of metabolism for an organism? I am trying to reconcile their ""lost genes include those central to cell metabolism, meaning it can neither process nutrients nor grow on its own" with their "The organism’s “replicative core” — the genetic components needed to reproduce itself — remains, making up more than half of its genome".
Replication (making DNA, RNA, and proteins, and ultimately dividing) is a highly energy-intensive and material-intensive process. What appears to be lost by Sukunaarchaeum are the genes to build basic building blocks (amino acids, vitamins, nucleotides) from scratch. It cannot find a sugar molecule and break it down for energy (it can "neither process nutrients nor grow on its own"). Yet it can take pre-made energy and building blocks and assemble them into a new organism.
What is the exact line between the host's metabolic contribution and the archaeon's replicative assembly? How "finished" are the raw materials that the host provides, and how does the archaeon's extremely reduced genome still manage the subsequent steps of self-replication?
You could argue the same way for a lot of parasite species, many of which are ridiculously more complex. Is a complex multicellular organism (an animal even) not alive because it needs to get some component needed for its reproduction from another species? If you get hung on such specific components, where do you draw the line?
So in this sense then, human beings themselves are obligate metabolic parasites on the planetary ecosystem, particularly on other life forms (plants, animals, microbes). The term "parasite" here is used in the metabolic sense of relying on another organism to produce essential compounds one cannot produce oneself. The molecules we must obtain fully synthesized from our diet are called essential nutrients. And for a Sukunaarchaeum, everything is an essential nutrient.
Agent Smith said a virus: https://www.youtube.com/watch?v=L5foZIKuEWQ
yeah, but he was biased against humans because of their smell. Though a virus might not be accurate.
Are there any animals which don’t need components from another organism? Isn’t heterotrophy one of the notable attributes of Animalia? There are the infamous sea slugs which eat algae then use the algae’s photosynthetic chloroplasts to photosynthesize the chemical energy they need, but they still need the algae to make those chloroplasts.
Interesting to realize that all animals are parasites (or perhaps symbiotes in some rare cases?) when you zoom out and look at the big picture. Almost makes me feel a bit guilty for not being a self-sustaining plant.
As I understand it, it's not so much that they got "hung up" on some specific capabilities for theoretical reasons, but that it's rare to find cells without these capabilities. In other words, it's nature that seemed so "hung up" on these things.
well people want simple models and explanations -- just like physicists want to model cows as "spherical boing boing cows"
We can survive without a constant stream of incoming raw materials. I wouldn’t think that makes us any less alive. Nor are we a parasite on the food.
You could make a distinction here in that we only need raw materials, we don't need another organism to reproduce. Mosquitos can also easily consume raw materials in the form of nectar to survive, but they need to take blood from other animals if they want to reproduce. If you go along this chain of thought, you can come up with arbitrary definitions.
We need mitochondria.
They are technically no longer individual life forms. They sure used to be, but we merged quite some time ago. Of course that opens a whole other can of worms with respect to who you really are. You're trillions of microorganisms living together and quite a few of them don't even share your DNA.
We need 20 different amino acids to build all our proteins. We can synthesize 11 of them (non-essential amino acids), but we must obtain the other 9 Essential Amino Acids fully formed from the food we eat.
I wonder if this minimal cell could be described instead as something between a bacteria and a virus. I am not a biologist, but IIRC viruses penetrate cells then hijack the cell's standard machinery to replicate itself, until the cell explodes; sort of like a DNA/RNA injection exploit.
For all the folks saying, "Isn't this just a virus?"
The actual paper states that the genome encodes transfer RNA's and ribosomal RNA's. I think that's a really important biological distinction missing from the popular press junket. The primary source material is well written and elucidates a lot more than the Quanta article. https://www.biorxiv.org/content/10.1101/2025.05.02.651781v1
> the bacterium Carsonella ruddii, which lives as a symbiont within the guts of sap-feeding insects, has an even smaller genome than Sukunaarchaeum, at around 159,000 base pairs
159 000 base pairs is ~320 Kbit, or 40 KBytes. I wonder, if that is the minimum size of a cell firmware. Also, if the cell is that simple, can we study it exhaustively and completely? Like, decipher every base pair in DNA, and determine what it is responsible for. And make an interactive website for that.
Makes me wonder, do geneticist count epigenetic methylation as information to add to the genetic information set ?
Isn't methylation more like temporary variables?
Kinda but they matter for the live being. Also there's hints that it impacts inherited traits too
This is the biological equivalent of sectorlisp.
That’s about the same size as the original Super Mario Bros
Reminds me of how the discovery of giant viruses - like truly huge viral particles - was immediately also followed by discovering "virophages" which parasitized them.
Which of course makes sense to some degree: if an adaptive strategy is successful enough, then parasitizing something which successfully implements it is going to be resource favorable (and likely, presumably by being a member of that species and just shedding components you don't need if you take them).
Indeed. Well deduced.
Inevitability of Genetic Parasites Open Access Jaime Iranzo, Pere Puigbò, Alexander E. Lobkovsky, Yuri I. Wolf, Eugene V. Koonin https://academic.oup.com/gbe/article/8/9/2856/2236450
Unsurprisingly maybe, DPANN archaea can also host viruses: https://www.nature.com/articles/s41564-025-02149-7 (Paywalled, but there’s a preprint at https://www.biorxiv.org/content/10.1101/2025.02.15.638363v1)
From the paper: https://www.biorxiv.org/content/10.1101/2025.05.02.651781v1
> ... we report the discovery of Candidatus Sukunaarchaeum mirabile, a novel archaeon with an unprecedentedly small genome of only 238 kbp —less than half the size of the smallest previously known archaeal genome— from a dinoflagellate-associated microbial community.
For comparison, the smallest bacteria genome, nasuia deltocephalinicola, is 139 kbp.
> According to the shocked researchers
What is this, some content creator run Biohacker Lab in some basement on Microflix premises?
Ominous voice: the tiny cell withdrew into the cracks of existence and saved it's entire code to be in the lines between, the Singular Point which was neither a fraction of space, nor a unit of time, hidden in the void of Chututululu's (33rd degree cousin of Cthulhu) dreams, written in the unspeakable language of the subtext of the book of neither life nor death, that nobody would decipher until the time was right AND GODZILLA GETS TO WALK THE EARTH AGAIN.
They were shocked. It is shocking.
Well tell them to quit playing with the stun gun.
Life's two most fundamental properties are homeostasis and reproduction. The loss of these two combined with its parasitic nature makes this cell a form on non-life.
You're being rigid about your preferred definition of life, but for what purpose? What is gained by categorizing this as strictly non-living?
Wikipedia on the definition of life:
> Since there is no consensus for a definition of life, most current definitions in biology are descriptive. Life is considered a characteristic of something that preserves, furthers or reinforces its existence in the given environment. This implies all or most of the following traits: [list of seven common traits of life]
> Life's two most fundamental properties are homeostasis and reproduction. > The loss of these two combined with its parasitic nature makes this cell a form on non-life.
This is a decidedly Eukaryote-centric take. Homeostasis in higher mammals is a complex network of genes -> RNA -> proteins -> metabolic pathways
Reproduction is also far more simple in organisms with binary fission cellular division.
A more appropriate scientific term would be obligate commensalism vs. "parasitic". That actually encapsulates their need for metabolic precursors from the host, but allows for tRNA, rRNA, origin of replication, etc...present in the organism's genome.
Lots of types of life give up on homeostasis along particular dimensions because the environment is doing it well enough. Viruses do reproduce.
If you say "well not by themselves" neither do humans.
No life exists "by themselves". Self-replication means using only its own DNA and not mangling with other's. Virii are not only parasites but dead matter (a ribonucl molecule surrounded by proteins that happens to stick to other cells, like dirt on the skin). Gut microbioma is parasite.
There is another life property that this object does not fulfill and is called Teleonomia, that is governed by an ultimate goal.
> that is governed by an ultimate goal.
I have bad news for you. Again, it's humans.
how do biologist consider virus like replication then ? which is a two-part system, the virus + the host (and even, a dense population of hosts)
First, context: a "life/not-life" distinction is far more "science" than science - widespread in "science" education, but rarely comes up in science research. (Might be interesting to create a list of similar?) Why the emphasis there... I don't know - perhaps because we teach by memorizing definitions and lists, not by learning design spaces and their landmarks? Or at least by giving exemplars without characterizing variance.
One of the few places I've seen it come up in science, was ecosystem multi-scale simulation software. Where virus was squarely in the heritable characteristics under selection pressure ("life") bucket, rather than abiotic or biogenic.
Informal "do you think of viruses as alive?" seems to vary by field. I've seen a marine bio labs be overwhelmingly yes. I've been told medical immunology leans no. But it seems more social-media engagement question than research question or synthesis.
Viruses are considered infectious agents rather than life forms per se.
<https://en.wikipedia.org/wiki/Introduction_to_viruses>
Not sure why you linked that particular article, as it does not mention anywhere whether viruses are alive (though it implies they're alive with the sentence "Vaccines may consist of either live or killed viruses").
They are infectious agents, but many life forms are infectious agents.
That article (and the more general article on viruses) both pointedly avoid referring to viruses as organisms, "any living thing that functions as an individual".
<https://en.wikipedia.org/wiki/Organism>
Which specifically addresses edge cases including viruses, which "are not typically considered to be organisms, because they are incapable of autonomous reproduction, growth, metabolism, or homeostasis".
<https://en.wikipedia.org/wiki/Organism#Viruses>
Specifically, viruses have no innate metabolism, or energy-producing chemical reactions.
<https://en.wikipedia.org/wiki/Metabolism>
The terms "live" and "killed" have historical origins, but would better be read as "active" or "deactivated", and the immediately succeeding sentence clarifies this: "Live vaccines contain weakened forms of the virus, but these vaccines can be dangerous when given to people with weak immunity."
For more on the distinction see: <https://www.biologynotes.in/2024/03/difference-between-live-...>.
And yes, there are infectious agents which also happen to be organisms, such as bacteria, amoebas, funguses, etc. Tuberculosis (Mycobacterium tuberculosis), many stomach ulcers (Helicobacter pylori), botulism (Clostridium botulinum), and e. coli poisoning (Escherichia coli) are all infectious disease caused by bacteria. Giardiasis is a G-I infection of the Giardia amoeba. There are numerous fungal infections (many UTI infections, athlete's foot, jock itch, nail infections).
Further down the non-life infectious agent chain are prion diseases such as Transmissible spongiform encephalopathy ("mad cow" disease in cattle, "Creutzfeldt–Jakob disease", amongst others). These are literally misfolded proteins, which lack not only metabolism but any genetic material (DNA, RNA), but still propagate.
More on infectious agents, a/k/a pathogens: <https://en.wikipedia.org/wiki/Pathogen>.
You misunderstood me. I wasn't claiming viruses are or aren't alive. I was pointing out you chose a citation that doesn't contain support for your claim. There are plenty of sources that would back you up, but that link doesn't.
> That article (and the more general article on viruses) both pointedly avoid referring to viruses as organisms
As if you expect people to carefully read the whole article, notice it doesn't mention anywhere whether viruses are alive, and conclude that by not mentioning this it supports your claim. By the same logic, it pointedly avoids saying viruses aren't alive.
The main article on viruses has a section that addresses directly whether viruses are alive (https://en.wikipedia.org/wiki/Virus#Life_properties):
> Scientific opinions differ on whether viruses are a form of life or organic structures that interact with living organisms. They have been described as "organisms at the edge of life", since they resemble organisms in that they possess genes, evolve by natural selection, and reproduce by creating multiple copies of themselves through self-assembly. Although they have genes, they do not have a cellular structure, which is often seen as the basic unit of life. Viruses do not have their own metabolism and require a host cell to make new products. They therefore cannot naturally reproduce outside a host cell—although some bacteria such as rickettsia and chlamydia are considered living organisms despite the same limitation. Accepted forms of life use cell division to reproduce, whereas viruses spontaneously assemble within cells. They differ from autonomous growth of crystals as they inherit genetic mutations while being subject to natural selection. Virus self-assembly within host cells has implications for the study of the origin of life, as it lends further credence to the hypothesis that life could have started as self-assembling organic molecules. The virocell model first proposed by Patrick Forterre considers the infected cell to be the "living form" of viruses and that virus particles (virions) are analogous to spores. Although the living versus non-living debate continues, the virocell model has gained some acceptance.
def not life. there is no sense in which a virus... 'does' anything, it's not agentic. it's kind of like a free-floating loaded spring.
ok, i get that, and now is a bacteria considered more agentic than a virus then ? (that's a bit of a side-question sorry). bacterias at least reproduce on their own so they check all the boxes.
So... where does it get its ATP? The article says it's lacking pretty much all metabolism -- does that include cellular respiration and/or fermentation? Does it just get its ATP all from its host, or does it make some itself and get some from its host, or what?
I think the genome might be mostly just the "config file". So the cell already contains most of the information and mechanisms needed for the organism. The genome is config flags and some more detailed settings that turn things on and off in the cell, at specific times in the life of the organism. From this point of view, the discussion about how many pairs/bytes of information are in the genome is misleading. Similar analogy: I can write a hello world program, which displays hello world on the screen. But the screen is 4k, the windows background is also visible, so the hardware and OS are 6-8 orders of magnitude more complex than the puny program, and the output is then much more complex than the puny program.
Virus are simpler and have challenged the definition of life for a long time already. This article excludes virus from life because they lack ribosomes.
Last time I checked, they are considered "not alive" when outside of a host, and "alive" when inside a host.
About size: "Genome size varies greatly between species. The smallest—the ssDNA circoviruses, family Circoviridae—code for only two proteins and have a genome size of only two kilobases;[61] the largest—the pandoraviruses—have genome sizes of around two megabases which code for about 2500 proteins"
https://en.wikipedia.org/wiki/Virus
The definition of life is also uninteresting. At its core it is just a vocabulary and classification issue. We humans invented the word life and we humans chose to make the word vague, confusing and differently defined among different people. An arbitrary vocabulary and definitional choice for a word “life” is not in actuality interesting to think about.
Yet people get hung up about it as if it’s a philosophical problem. It is not a philosophy problem. The word is loaded and you’re simply spending an inordinate amount of time trying to define some made up boundary of what fits this category you made up. It is a communication problem disguised as deeper.
It is a question in philosophy. It is the difference between being considered a conscious being, and not. Since for now our definitions of a conscious being is tied to being alive (when is a human alive and not death?). So obviously it has implications on ontological questions. It fundamentally limits our understanding of what exists and just as important, why we exist.
Are the concepts "conscious" and "life" linked at all?
Bacteria, fungus and plants are not usually seen as conscious but are usually seen as alive.
All conscious things are alive (unless AI is conscious) but not all alive things are conscious.
It's like the word "planet", ultimately a tired game of definitions.
See also: “Microbe with bizarrely tiny genome may be evolving into a virus” – https://www.science.org/content/article/microbe-bizarrely-ti...
Which, BTW, is about the same researcher and microbial host/parasite pair. More info, so I'm not complaining.
Yeah, I should have mentioned that. Article about the same topic and preprint, but released earlier this year.
Maybe devolving would be a better term if that's the case
The standard definition of life is too restrictive.
I suggest
Or, in other words, things that can evolve.I find the idea that viruses aren't alive ridiculous.
That's an interesting definition, but it does have some issues.
Is an infertile animal (which can't reproduce) dead? What about a nerve cell (which have differentiated too far to become a reproductive cell)? Or a red blood cell (which has no genome)?
From the other end, is a genetic algorithm alive? What about a manuscript? Manuscripts are copied (so they reproduce), and have frequent copying errors, which propagate.
Atoms and sub-atomic particles fit this definition.
Machines fit this definition.
Fire fits this definition.
Truth is "life" is not a distinct category. We just think of life as complex life. A complex system that mines energy gradients to preserve and replicate its forms.
But there's no hard boundary. It's just in our head.
How do any of those things fit that definition?
Code can fit the definition. Genetic algorithms.
Yep.
People always come up with people-centric definitions. They need to be updated based on what are the fundamental characteristic of something that is alive.
The current, more standard definition, seems to be based on metabolism. I disagree and argue for reproduction and evolution.
No, none of those can mutate, that's the point of "and mutate heritably"
Crystals can "reproduce", but it's always the same (there can be errors, but they don't inherit), so they don't count.
And atoms don't reproduce, so I'm missing your point there.
Reproduction in time and reproduction in space are connected. If atoms couldn't reproduce (I can sense most readers knee-jerking reading this), they'd be all unique, wouldn't they. And yet they aren't.
You could say "they have no heritability", and not the way you expect, I guess, but they all inherit the same local laws of physics, and they may even impact those laws, thus forming a feedback loop, and clearly there are googols of them in clusters, same weight, same energy, same polarity, same properties, same states, much like you see with any other species in nature, in fact in far lesser numbers.
If robots are made in a factory, does this count as reproduction? If not, why not. Does a mother's womb not resemble a "baby factory". A baby does not create itself. Always something else creates you.
We have clusters of "common sense" about these things, and most of what I said immediately sounds stupid to "common sense". Yet common sense falls apart if you start thinking about it. But Internet is not EXACTLY conductive to "thinking about it". It's all about the hot takes and the current consensus. Then time passes, and that consensus seems truly unenlightened.
I’ve been thinking about a wild theory regarding the incredible biological complexity we see in mammals today.
What if our bodies (apart from the brain) are actually the result of an ancient aggregation of once-separate "organisms" that evolved to live symbiotically?
Over millions of years, their DNA might have fused and co-evolved into a single, unified genome. What began as cooperation between distinct life forms could have gradually become inseparable, giving rise to the intricate multicellular systems we now take for granted.
It's called Symbiogenesis [0] and it's not at all a wild theory. But it's limited to cell components, not multiples organs fusing to create something as complex as a mammal.
[0] https://en.wikipedia.org/wiki/Symbiogenesis
This isn't a wild theory or a novel one. It's well-established that endogenous retroviruses alter DNA and are inherited. In addition to the primary genome being modified this way, all mitochondria are symbiotic organisms inside plant and animal cells, with their own DNA, and are vital to life. Same thing for chloroplasts in plants. And then there are gut bacteria, which are vital to life, symbiotic, and directly influence evolution and the genome.
Why do you say "apart from the brain"?
Also, as others have noted, your idea is not necessarily wild. Certainly, at the sub-cellular level, there is tremendous evidence that symbiosis played a part in creating "higher level" organisms (i.e., eukaryotes).
Many genomes are like a junk-yard with fossilized relics of infectious agent nucleic acid (e.g., viruses), etc. Apologies for the junk-yard / fossil mixed metaphor.
https://en.wikipedia.org/wiki/Intragenomic_conflict
I believe that we’re living in that situation now. I don’t think life can be divided into smaller organisms. That there is just one complex life that we failed to see based on our past prejudice.
You should look into the origin of mitochondria.
400K should be enough for any body
Maybe this is a case of an inception of overlapping genes?
Impressive. However, still a-ways to go before its as degenerate as viruses like SARS-CoV-2 (which have an order of magnitude fewer base-pairs)
This is cool but doesn't say much about the definition of life IMO. They're obligate parasites. This isn't a new category. They're still eating stuff from their host (probably, given the caveat later in the article), and still using it to replicate, it's just a more limited diet.
> They're still eating stuff from their host
They aren’t. Apart from DNA replication, transcription, and translation, their genome lacks elements encoding for even the most simple metabolic pathways.
Then where are they getting the materials to replicate? Where are they getting the energy? Magic? No, they're pulling pre-metabolized materials and energy from the host.
Which is exactly what I said.
We don’t even fundamentally understand physics yet. Certainly there is much to life that we don’t understand.
This is not so much about the understanding of life as it is about the definition of life.
I don’t think a precise definition of life is particularly important or of particular interest to most biologists. This thing is life in the sense that it’s definitely in scope of being studied by biologists (same is true for viruses, of course). And the reason it is speculated that it may be crucial to understanding life is mentioned in the article: “This organism might be a fascinating living fossil—an evolutionary waypoint that managed to hang on.”
Eh, you're quibbling with words. We're getting closer to the quantum (indivisible) definition of life, and that's understanding.
I don't think that they are. The term life, as it's currently defined, is not very useful. The reality is that there is a very colorful spectrum of microscopic biology and that a single bin of "alive" and "not alive" is like trying to paint the mona lisa with a single pixel.
This scishow video gives a good look at the tip of the iceberg.
https://youtu.be/FXqmzKwBB_w
As they said in another comment, life is the ability to decrease entropy. That definition would tie in quantum mechanics.
We understand enough physics to model all the possible interactions life might have on this planet. Unless this planet is having a really bad day.
An interesting counterpoint to how little we know, and/or how useless in practical terms our quantum level understanding of physics is, is chemistry.
Chemistry is adjacent to physics, at least classical physics and the standard model, so you might think that we should be able to use our knowledge of physics to determine things like atomic bond "angles" and the protein folding problem, yet even this smallish step up in abstraction from physics puts us in a realm where we know very little. DeepMind's AlphaFold, now able to correctly predict 90% of protein folding in agreement with experimental determination, is mostly based on learning from experimental data, as well as evolutionary consideration of proteins that co-evolved, etc.
It makes you wonder how useful the reductionist model really is in terms of understanding higher level dynamics. Maybe different levels of abstraction like physics, chemistry, etc, are really a lot more independent than is commonly thought.
Maybe better to say "We understand enough physics to model all the possible interactions PHYSICS might have on this planet".
There are many levels of abstraction between quantum/particle physics and life, or even just cosmology (things like dark matter, etc), that we really know very little about.
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Please avoid generic tangents and political/ideological battle on HN.
https://news.ycombinator.com/newsguidelines.html
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Me thinks, sir, you think you knowth, but not.
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You misunderstood my original statement. SCOTUS struck down RvsW, which I think is wrong- both morally and scientifically. You shouldn't name call, leave me alone or I will report you.
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> Its easily googlable or ChatGPT-able. Dont be intentionally dense. You are just making your "side" look dumb.
This is an unacceptable comment on HN. It breaks several guidelines, including those listed below. Please read the guidelines and make an effort to observe them whenever participating here. We've had to ask this of you multiple times previously.
Be kind. Don't be snarky. Converse curiously; don't cross-examine. Edit out swipes.
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Please don't post shallow dismissals, especially of other people's work. A good critical comment teaches us something.
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The ultimate form of outsourcing.
Which makes C. Regius a very tiny CEO? :)
Only if it has a mechanism to send signals into the host and cell. For the CEO metaphor to hold, I'll accept that these signals can be entirely ignored, but they need to be transmitted.
There must be some interaction with the host involved. Otherwise there is no point in being hosted or stripping off own features.
What do you mean? The interaction described in the article is just of the small cell stealing nutrients from the host's pouch. That seems like enough of a "point" for the parasitic cell, while giving it zero incentive to advertise its presence with signals.
Talking about tiny cells and staring at a tube with liquid. Made me chuckle.
Hm. Not the biggest fan of the "parasite" framing given how little we know. I feel the default should be something more like lichens.
Life is the process of decreasing entropy. If they stick with that definition, they’d be fine. And they’d find out that life is even more abundant than they can imagine.
This is one of those things that sounds profound, but only until you think about it. Depending on how you read this, it either excludes life entirely or includes all sorts of things that are not meaningfully alive.
1. Living things locally decrease entropy but globally increase it.
2. Many other processes do the same. As chermi noted, a liquid solidifying has the same characteristic.
I definitely choose the second of your two outcomes. That it includes all sorts of things that you think are not meaningfully alive. But these things are actually life.
Yes, living things locally decrease entropy and that’s my point.
And maybe I should’ve been more clear for people who cannot grasp new understandings, anything that can decrease its own entropy is living.
I mean, do you think life has nothing to do with the organization matter into a lower entropy state?
What? A liquid solidifying is life?
Water does not decrease its own entropy. If you can’t understand the distinction I’m making then you do not have the imagination and creativity to create new understanding.
A glass of water in a cold environment radiates away heat until it freezes, decreasing its local entropy and increasing global entropy.
> If you can’t understand the distinction I’m making then you do not have the imagination and creativity to create new understanding.
Perhaps you could explain your distinction instead of insulting people. It’s possible you have some interesting and insightful distinction but as of now you’ve not explained it nor given any examples of this “more abundant” life.
I’m not insulting you. I’m pointing out a reality. You’re reading comprehension is failing you right now.
Water does not freeze itself. That is the distinction. But myself, as a living being, can turn water into ice. And I can create an organize materials inside of my own body.
I pointed out something interesting. The least thing you could do is actually look up to see if there’s any validity or research on what I’m talking about.
By more abundant life, I’m talking about how the definition of life we have is limited, but it’s ever expanding based on the papers of the original post. I’m talking about a greater expansion of our understanding of life that’s discussed in papers that deal with entropy and life.
For instance:
https://www.quantamagazine.org/a-new-thermodynamics-theory-o...
But this has been a topic of conversation since the early 1900s. It’s not like I’m saying anything new.
> I’m not insulting you.
At least own it. Saying someone lacks imagination and creativity and now reading comprehension is absolutely insulting.
> I pointed out something interesting. The least thing you could do is actually look up to see if there’s any validity or research on what I’m talking about.
I can’t look up anything based on your vague comment. That’s why I asked what you mean.
> For instance:
Thanks. I’ll take a look at that article.
> Saying someone lacks imagination and creativity and now reading comprehension is absolutely insulting.
I said: "You’re reading comprehension is failing you right now." The "right now" part menas that I am not saying it does not exist, just that they are not understanding what is written.
Why is it an insult to say someone lacks creativity? It was objectively true to me and it is not an insult, just a truth. Like if someone has red hair. At worst it was my opinion.
You know what an insult is? To take what I said to think that I meant that water turning to ice was life.
Can we also study very small collections of sand to challenge the definition of what counts as a heap?
This sounds more like a SuperVirus than a cell to me ¯\_(ツ)_/¯