This article is framed as if there is something novel and profound here, but the "aliveness" of mitochondria is simply a matter of how we choose to apply the label "life" - a human linguistic construct that exists independently of the biological phenomena. This is not a new discussion - science has been considering this question for many decades, just as it has with viruses. These all come down to arguments about semantics and don't add anything to the science.
Mitochondria are fascinating and there is still a huge amount to learn about them but they are totally dependent on the cell's machinery. Most of their genes, the code for their structure, are in the nuclear DNA. A glaring omission if you are trying to make the case that mitochondria are independently living. My heart can exist independently of me, and be transplanted into other people, but does it mean that it is alive?
The implication of the whole article is that there something we have missed. This really isn't the case. Lynn Margulis's endosymbiotic origin of mitochondria was challenged by many, and it did spark a scientific debate - that's how science works. She won the argument comprehensively decades ago and is well established science. There have been many such endosymbiotic events in the history of life - there are subfields of evolutionary biology that study these processes.
> These all come down to arguments about semantics and don't add anything to the science.
This accurately describes much of science...
> My heart can exist independently of me, and be transplanted into other people, but does it mean that it is alive?
The cells that comprise your heart are very much alive, but they will die without support infrastructure. They live, they replicate, they die -- like every cell in your body. If I relocate you to the moon without support infrastructure, you would die too -- and yet (I think?) you are probably alive.
"Very much alive," in the sense of being a living organism in their own right. By that standard, each cell in the human body can also be considered a separate living organism, simply cooperating with other humans cells in a complex way. It makes sense, since we have no problem identifying the trillions of bacteria cells living on or in the human body as separate living organisms.
"Sperm and egg cells, known as gametes, fuse during fertilization to create a zygote. "
Since all humans were just 2 cells at one point. It seems to follow that the entirely of the code for what a human is, is contained in just those 2 cells.
Not just code for a finger. But even code for our deeply ingrained fear of snakes. Was just at one point contained in those 2 cells. Kind of blows your mind.
If they are separate living organisms, then there seems something recursive about humans if they can be just 2 cells at one point.
I know this is not exactly your point, but it's important to remember that it's not exactly everything. The intra-uterine environment has a serious contribution to your development, and almost certainly transplanting the fecundated cell into a different mother would lead to a different person being born. Especially when it comes to things like intestinal flora, which mostly seems to get "seeded" from the mother during birth. Even the milk you ingest after birth significantly influences certain aspects of your basic biology (mostly the immune system).
They're as much a human as some living cells I shed on the floor. Alive and genetically human.
Being a person involves some level of thought, not just existing. If you ripped my brain completely out, and kept my body alive, most would consider the brain removal the time of death. That's when the person they knew died.
When you get a scrape and you bleed, thousands of your cells burst forth and die.
Each has the same set of information necessary to rebuild an entire person. Have you committed mass murder?
The strongest arguments against abortion don't hinge on whether the fetus is a person. The question of abortion ultimately boils down to whose rights we privilege: those of the mother, or the fetus?
Why would the fetus have any rights that are not automatically defeated by the rights of its mother if it's not a person? All anti-abortion arguments that I'm aware of start by arguing that the fetus deserves the rights of a person, and then proceed from there. Could you present a counterexample?
"Potentiality" - this view argues that regardless of whether the fetus is a person, it has the potential to become a person, and thus inherits some moral consideration.
"Value of Human Life" - the argument that human life - at any stage of development - has intrinsic value and thus should be protected.
Heck, a sperm and an egg in separate containers have exactly the same information as a fertilized egg. That's a powerful argument for having a clear idea of what creates moral personhood.
Otherwise you're in the same camp that believes a sky daddy breathes a soul into your baby at conception and that IVF is the work of Satan.
In that case, it would also be a good argument against killing any single-celled organism, since it's a life that already exists. But life on Earth is cheap.
I don't think that DNA is just procedural assembly instructions. Though maybe more akin to something like the encoding of a neural network. Granted I have a basic understanding of DNA.
Maybe you saw this paper about that idea - The Genomic Code: The genome instantiates a generative model of the organism.
"Here, we propose a new analogy, inspired by recent work in machine learning and neuroscience: that the genome encodes a generative model of the organism. In this scheme, by analogy with variational autoencoders, the genome does not encode either organismal form or developmental processes directly, but comprises a compressed space of latent variables."
Yeah?! You think so? Perhaps yours a strong argument against consumption of anything born this way, renders all meat consumption a bad thing with these same arguments… I bet 5€ you had your burger this morning and it had plenty of already dead cells in it, not to account for the yeast in the bread…
> From the moment the egg is fertilized, a new person exists.
The potential for a new person exists. Just as the potential for new people exist in a collection of sperm and egg cells.
The only difference, which you seem to be latching onto, is that now that potential has been turned into a more specific one. Why do you think that makes any real difference? It seems like an arbitrary and abstract argument that depends on an almost mystical perspective.
> This is a strong argument against abortion.
It really isn't. In fact, it's fallacious, because to accept the argument, you have to accept premises that produce the desired conclusion - i.e. it's question-begging, assuming its conclusion.
It would be a so-so argument if it was true. (It is not) How DNA is expressed is a part of the story as well which involves many environmental factors both in utero and after birth.
We do not totally understand how it works, but there are heritable traits not passed via DNA - the one often in the news is women with emotional trauma pass that trauma on to their children, and those children show those symptoms even if raised in a happy home with 0 contact with the mother.
It is a philosophical argument, not a scientific one. One which if we try and reason based on how special nature treats embryos quickly falls apart anyways...
For the most part epigenetic traits seem to be transmitted by DNA too. Rather than being encoded in the pattern of base pairs, the epigenetic changes are made by slightly modifying the structure of individual bases. Think of it as adding tags to instructions.
The final categorization is the least interesting part though. If we understand the origins and mechanics of how the once parasitic organism became an integral part of almost all complex life, does arguing the semantics of what label you put on it really add much value?
To reframe it: what you’re really doing is arguing about the definition of alive. In this case my opinion is: who cares. I fail to see how expanding the definition or being precise here adds anything.
> does arguing the semantics of what label you put on it really add much value
Refining the definition of something often helps provoke new understanding and tests of the limit of that refinement. It seems like a critical requirement in the "form a hypothesis" step of the scientific method.
i might be wrong but corporations/institutions never sponsor R&D in all directions so framing/phrasing is vital. but, from a philosophical pov, I agree with you.
We probably can keep a heart alive outside of body, through artificial means, for minutes, maybe hours - and I mean keep it functioning, not just chilling it to slow its death. It's plausible we'll learn to be able to keep it alive for days, months, years, decades. At which point we could say that the "supporting infrastructure" of the rest of a human body isn't necessary for the heart to be independently alive?
What if we do it all on the Moon, or Mars? How does Gaia feel about it? We already know that it's theoretically possible, if not yet achievable in practice, to create artificial environments capable of supporting human life indefinitely - or, on a long enough timescale, bootstrap an independent, self-sufficient biosphere. The two are, in the limit, the same thing anyway.
Or are we going to argue that human technology is, by extension through causality, a part of life on Earth, and therefore a part of Gaia itself? Is Gaia in all of us, and will it persist after Earth dies if humanity is still around somewhere else?
All in all, I suppose the correct definitions of terms are the ones that are most useful in a given context :). "Categories were made for man, not man for the categories", and all that.
I’m not sure what you are arguing against. For me, the article offered a lovely reminder that life is special. Life involves mechanisms but it is more than a machine. And with an attitude that our lives our symbiotically bound to another living organism (or 10^17 of them) we gain a valuable humility — one that might afford us new perspectives on how to make them all happy and flourish. That’s the promise— not just a spiritual connection to the aliveness of mitochondria, but a pragmatic orientation towards their health and wellbeing. And there is a lot of scientific opportunity to explore there.
As I said in another comment, I think that mitochondria are fascinating, understudied and a rich area for research.
We are bound to the myriad other pieces of DNA that all have different evolutionary histories within us, we are symbiotically bound to many strands of life on many levels. We are just one strand, a part of a singular whole, bound to all strands of life beyond us. This view of life led me to science. I totally think that this view of biology is not properly appreciated by most scientists.
But this article was presented as a scientific piece and made the explicit claim that mitochondria were alive which is a semantic argument that doesn't have a scientific answer.
It is a well written piece that made it to the top of hacker news and it's great to see the debate.
But it just isn't true that mitochondria are alive by our currently accepted definition of alive. This is an old debate in biology that was settled years ago. There is nothing in this paper that wasn't known to mainstream science decades ago, but it is presented as a novel scientific viewpoint.
> it just isn't true that mitochondria are alive by our currently accepted definition of alive. This is an old debate in biology that was settled years ago.
Sorry, but that’s an overreach. There are many “accepted” definitions” of life across different scientific fields. According to Wikipedia, there are at least 123 definitions of life — and there is not scientific consensus. Mitochondria are alive based on some definitions and not alive based on others.
Expecting life to have total autonomy in self-sustainability is absurd. Otherwise somatic cells or even people would be not alive.
And the argument that mitochondria are not alive because they can’t encode all their own proteins — well, I’ll point out that humans can’t produce all amino acids, either. As a thought experiment, if humans couldn’t produce a certain essential protein — and had to rely on a symbiont, would that mean humans weren’t alive?
Finally I’ll point out that Mitochondria can be healthy or flourishing — and they can be sick and die. How can something that is not alive, die?
It’s ok to argue for a narrow definition. But please don’t present this argument as though you are the defender of clear scientific conclusions. There simply isn’t consensus on this across the sciences.
I agree I didn't phrase that right. It was a short cut.
There has been debate over whether mitochondria can be called alive since at least 1890. For many years the vast majority of mitochondrial biologists have avoided the binary alive/not alive classification because there is a spectrum of 'livingness' and we can draw the line anywhere we like.
Picking a different line position is not scientific, it is semantics. What do we mean by the term 'alive'?
The article presented a profound new way of viewing the living state of mitochondria that was going to transform the world. It said nothing new, and failed to make any reference to the long term debate.
But it was a nicely written interesting article and mitochondria are going to be hugely important therapeutic area in the future.
I think they are arguing against the subtitle of the article:
"Recognizing that mitochondria are alive will open new horizons into how we learn about, and build with, biology."
Which seems a stretch based on semantics.
> The implication of the whole article is that there something we have missed.
I think this article is talking to people who haven't internalized the details of the scientific consensus. Those people are still going around, talking about "life" and making decisions based on the flawed understanding this article is critiquing. I think it's likely that the thing that "has been missed" is not narrowly scientific in the way you seem to be thinking - but more about broad implications and worldview.
I am not sure what exactly the 'broad implications and worldview' are here that are being challenged. The article is presented as a scientific opinion and references scientific research and has a doi number for citation (Cite: Liyam Chitayat. “Mitochondria Are Alive” Asimov Press (2024). DOI: https://doi.org/10.62211/38pe-75hu). What do you think that the article was challenging?
Obviously the article is challenging the view — scientific or not — that mitochondria are not living.
Side note: previously I was funded by NSF and NASA to study such questions from biophysics and astrobiology.
That said, this was a delightful read. I did not realize or conceive of mitochondria as, like bacteria in our bodies, independent living networks with unique genomes, evolution, and flows of information and energy.
Reading about the health benefits of “external mitochondria” made me think about when I hug my dog: are we exchanging mitochondria, perhaps?
> Most of their genes, the code for their structure, are in the nuclear DNA.
Are they? I was under the impression that mitochondria are closer to pseudo-cells living inside human cells.
Wikipedia seems to confirm this [1]:
> Although most of a eukaryotic cell's DNA is contained in the cell nucleus, the mitochondrion has its own genome ("mitogenome") that is substantially similar to bacterial genomes.
There's a specific page on Wikipedia about Mitochondrial DNA [1], where it is clearly said that:
In the cells of extant organisms, the vast majority of the proteins in the
mitochondria (numbering approximately 1500 different types in mammals) are
coded by nuclear DNA, but the genes for some, if not most, of them are
thought to be of bacterial origin, having been transferred to the eukaryotic
nucleus during evolution. (citing [2])
See below on Wikipedia: "Most proteins necessary for mitochondrial function are encoded by genes in the cell nucleus and the corresponding proteins are imported into the mitochondrion. The exact number of genes encoded by the nucleus and the mitochondrial genome differs between species."
Yea I would def. not call mitochondria "alive" since they are so deeply integrated with the rest of the cell & vice versa.
mito is like <100k bp vs 3000000k bp in human genome (bp = base pair = "character" in a string)
principle derives from the concept of "the selfish gene" or "the red queen" these famous books on the topic. Arms races between X and Y chromosome. Arms race between nucleus and mitochondria, and so on.
or put it this way. why do all animals have sex? because it generates gene sequences that confer fitness more efficiently than self-replication (which is the typical repro method of unix programmers)... .. generates such gene sequences for NUCLEAR DNA that is, mito DNA comes from mom only (the red queen.. .. "mitochondrial eve" ... "y chromosomal adam".. etc). and thus the mito is fundamentally unable to wield the power of evolution, completely evolutionarily outclassed by those nuclear chromosomes. thus exporting all its genes to the nucleus, conferring advantage to all such progeny with their superior power supply
I don't understand this definition of "alive". Isn't every cell in my body alive? There are definitely differences between an alive cell and a dead one.
> There are definitely differences between an alive cell and a dead one.
Energy flow is the difference. but then everything has an energy flow. Losing and gaining electrons. So it is possible that literally everything is alive, don’t you think? Maybe the problem is is that we’re trying to make a definition where none ultimately really exists.
what about obligate intracellular parasites like mycoplasma? They are awfully close to mitochondria but we think of them as alive. They've lost many of their genes and can't survive without the host. Looking at those, you could almost see a path from an obligate intraceullular parasite to an organelle derived from a phagocytosed prokaryote.
But it does. How many grains of send form a heap? How many atoms form a fluid? Is it something a particle or a wave? The line can be drawn depending on specific problem, on how useful a heap/fluid/particle/wave model for this specific application.
A label (abstraction) allows us to bring corresponding tools that were developed for it. If you can count trees then the same math can be useful to count people.
Arguing about where you draw the line doesn't advance anything, it just muddies the water. We have robust definition of what is and isn't alive built by consensus. Mitochondria fall into the 'not alive' category by our definition. Presenting decades old scientific views as evidence that this categorisation is wrong doesn't add anything. This article has had far more exposure than some really groundbreaking science and it adds nothing.
My point is more general: there may be multiple useful descriptions of “reality” depending on context. It is almost _trivially_ (tautologically) true. Ask two different programmers to implement something and look at what abstractions they create depending on unrelated non-functional requirements. Here’s specific example: imagine you are writing “what-if” type of article about a table: if you are interested in whether it holds your weight then you might talk in terms of tension, compression, mechanical forces. If you are interested in whether you can hide behind it from x-rays then terms such as radiolucent, atomic composition might be useful.
I have no idea in what context “mitochondria are alive” notion might be useful (but it doesn’t mean there is none).
This "aliveness" debate reminds me of the "11.000 years old dog". Basically a tumour that has been spreading from one dog to another for thousands of years.
> My heart can exist independently of me, and be transplanted into other people, but does it mean that it is alive?
Your heart cannot exist independently of you as a heart. It is only a heart in name, as it does not function as a heart. Its identity as a heart depends on its ability to function as a heart within some organism. The same can be said for any part or organ. A severed hand is a hand in name only. A corpse is not a body, as it no longer functions as one.
A transplanted heart becomes a heart once more. A reattached hand becomes a hand once more. If you think this is weird, then you haven't done your metaphysical homework. Why should it be weird? It could only be weird if you have made certain (unexamined) metaphysical presuppositions. The structure of a heart removed from an organism persists long enough that it can become reintegrated into an organism such that it functions once again as a heart.
But also note that the matter composing a heart itself isn't fixed. About 1% of heart cells are replaced per year in the young. So if function and structure can survive transient material change, and the matter that makes up a heart can assume and lose and reassume its identity as part of a heart, then why can't a heart lose its identity as a heart when removed, and regain its after it is implanted back in?
> There have been many such endosymbiotic events in the history of life - there are subfields of evolutionary biology that study these processes.
Exactly, if mitochondria is alive then so is chloroplasts and who knows what else. The line needs to be drawn somewhere, also life and death isn't as clear-cut as many used to believe
I think questions like this make science fun for the uninitiated because it represents both the uncertainty and the intense investigation and evidence discovery process involved in tearing hazy things and recovering concrete truths in the process
Can you elaborate on this comment? What should popular biologists like Michael Levin be saying on every podcast/interview and why? Serious question from someone who is familiar with Lynn Margulis but not Michael Levin.
I don’t disagree with your take. The concept of the semantics of “what is alive?” has been going on for a long while now.
Have you considered that this is a more formal version of a Bill Nye science explainer, but for adults?
The reason I say this is that while unintended (I think) your post has a, “of course they’re alive, we’ve known this forever” vibe, which can inadvertently come across as condescending.
I don’t mean to pick on you, we’re all guilty of such speak when we deem concepts to be obvious or well known.
Your post reminds me of the “1 in 10,000” XKCD comic:
I agree with you, which is why I wrote this- but if you google "are mitochondria alive" gemini says it isn't. And yes, the cells in your heart have an effective and potenitial niche!
We seem to have many tools to engineer viruses, but few to engineer mitochondria- perhaps considering them as alive could change that!
I am not sure you should be relying on an LLM as any indication of anything...
More seriously, considering something as being alive in order to engineer them better does not necessarily change the fact of them actually being alive or not, in my opinion.
If LLMs work the way I understand them to, they are trained on large corpora which contain a statistical preponderance of statements which are consistent with the current scientific mainstream, so it may not be completely crazy to try doing this; you'd get the scientific mainstream explanation, and possibly a few alternative hypotheses if they had enough literature support.
Why would it be consistent with the scientific mainstream? Unless there's evidence that scientific reports and material are specifically up-weighted during training and prioritised somehow, whatever an LLM says will be only consistent with its training material, which could have any proportion of fake articles, Reddit posts, Quora responses, encyclopedia pages and joke blogs
> which are consistent with the current scientific mainstream
This seems to require a high amount of curation of training inputs, but I haven't done real digging into it, just going off the more casual "all of stackoverflow" or "all of reddit" type comments frequently thrown around. But if there is such a curation I'd agree, I just don't think there is that curation.
Eukaryotes generally can’t survive without mitochondria either. It seems silly to discuss if different subsystems in a living organism are independently “alive.” It’s a bit like arguing if just the wings or just the engine of an airplane are flying machines.
You are completely right that we should be thinking far more creatively about manipulating mitochondria. There are a lot of diseases (including Covid) that have mitochondrial aspects. I just don't think calling them alive helps, other than to get you some decent exposure on HN :)
Mitochondria are fascinating and there is still a huge amount to learn about them but they are totally dependent on the cell's machinery. Most of their genes, the code for their structure, are in the nuclear DNA. A glaring omission if you are trying to make the case that mitochondria are independently living. My heart can exist independently of me, and be transplanted into other people, but does it mean that it is alive?
The implication of the whole article is that there something we have missed. This really isn't the case. Lynn Margulis's endosymbiotic origin of mitochondria was challenged by many, and it did spark a scientific debate - that's how science works. She won the argument comprehensively decades ago and is well established science. There have been many such endosymbiotic events in the history of life - there are subfields of evolutionary biology that study these processes.