stevenjgarner 4 hours ago

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?

  • sigmoid10 3 hours ago

    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?

    • stevenjgarner 2 hours ago

      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.

    • tshaddox 2 hours ago

      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.

    • pron 3 hours ago

      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.

      • sysguest 2 hours ago

        well people want simple models and explanations -- just like physicists want to model cows as "spherical boing boing cows"

    • matt-attack 2 hours ago

      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.

      • stevenjgarner 24 minutes ago

        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.

      • sigmoid10 2 hours ago

        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.

  • astrobe_ an hour ago

    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.

pretzellogician 5 hours ago

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

  • oersted 4 hours ago

    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.

  • flobosg 4 hours ago

    A nitpick: Although similar in some aspects, archaea are not bacteria; they are classified under their own phylogenetic domain.

  • api 4 hours ago

    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.

    • smallmancontrov 4 hours ago

      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.

    • estimator7292 an hour ago

      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.

    • 0134340 2 hours ago

      >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.

    • ferfumarma 3 hours ago

      > 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.

      • threethirtytwo an hour ago

        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.

        • cozyman 35 minutes ago

          I'd like to see some form of evidence that creatures can change kinds, it seems impossible to me, how do you account for that?

      • api 15 minutes ago

        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.

    • alonmower 3 hours ago

      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.

codedokode 4 hours ago

> 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.

  • ErroneousBosh 4 hours ago

    This is the biological equivalent of sectorlisp.

djoldman 5 hours ago

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.

  • russdill 5 hours ago

    For comparison, the smallest bacteria genome, nasuia deltocephalinicola, is 139 kbp.

Y_Y 2 hours ago

400K should be enough for any body

empiricus 4 hours ago

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.

subroutine 3 hours ago

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)

freakynit 4 hours ago

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.

  • busyant 44 minutes ago

    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.

  • caymanjim 3 hours ago

    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.

  • bavell 3 hours ago

    You should look into the origin of mitochondria.

  • Noaidi 3 hours ago

    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.

andrewflnr 3 hours ago

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.

  • flobosg 3 hours ago

    > 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.

flobosg 5 hours ago

See also: “Microbe with bizarrely tiny genome may be evolving into a virus” – https://www.science.org/content/article/microbe-bizarrely-ti...

  • IAmBroom 5 hours ago

    Which, BTW, is about the same researcher and microbial host/parasite pair. More info, so I'm not complaining.

    • flobosg 5 hours ago

      Yeah, I should have mentioned that. Article about the same topic and preprint, but released earlier this year.

  • HarHarVeryFunny 4 hours ago

    Maybe devolving would be a better term if that's the case

smollOrg 5 hours ago

> 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.

  • IAmBroom 5 hours ago

    They were shocked. It is shocking.

    • moffkalast 5 hours ago

      Well tell them to quit playing with the stun gun.

tete 3 hours ago

Talking about tiny cells and staring at a tube with liquid. Made me chuckle.

zkmon 5 hours ago

The ultimate form of outsourcing.

  • b3lvedere 5 hours ago

    Which makes C. Regius a very tiny CEO? :)

    • falcor84 4 hours ago

      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.

      • zkmon 3 hours ago

        There must be some interaction with the host involved. Otherwise there is no point in being hosted or stripping off own features.

        • falcor84 an hour ago

          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.

XorNot 5 hours ago

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).

cnnlives1987 5 hours ago

We don’t even fundamentally understand physics yet. Certainly there is much to life that we don’t understand.

  • jacquesm 5 hours ago

    This is not so much about the understanding of life as it is about the definition of life.

    • tshaddox 4 hours ago

      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.”

    • IAmBroom 5 hours ago

      Eh, you're quibbling with words. We're getting closer to the quantum (indivisible) definition of life, and that's understanding.

      • willis936 5 hours ago

        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

      • Noaidi 3 hours ago

        As they said in another comment, life is the ability to decrease entropy. That definition would tie in quantum mechanics.

  • russdill 5 hours ago

    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.

    • HarHarVeryFunny 3 hours ago

      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.

  • bloomingeek 4 hours ago

    Let SCOTUS have a look, they seem to know what life is without the benefit of any bothersome science.

tbrownaw an hour ago

Can we also study very small collections of sand to challenge the definition of what counts as a heap?

catlikesshrimp 2 hours ago

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

  • threethirtytwo an hour ago

    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.

    • pfdietz an hour ago

      It's like the word "planet", ultimately a tired game of definitions.

Noaidi 4 hours ago

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.

  • dpark 2 hours ago

    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.

    • Noaidi 2 hours ago

      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?

  • chermi 3 hours ago

    What? A liquid solidifying is life?

    • Noaidi 2 hours ago

      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.

      • dpark an hour ago

        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.