[HN Gopher] How the placenta evolved from an ancient virus
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       How the placenta evolved from an ancient virus
        
       Author : _Microft
       Score  : 354 points
       Date   : 2021-01-06 07:13 UTC (15 hours ago)
        
 (HTM) web link (whyy.org)
 (TXT) w3m dump (whyy.org)
        
       | ARandomerDude wrote:
       | It's amazing how quickly people leap to conclusions in the field
       | of evolutionary biology. Fact: a portion of the placenta's
       | protein sequence is very similar or identical to a virus.
       | Unsubstantiated (and pretty wild) conclusion: the placenta is the
       | product of that virus. We would never accept that kind of
       | mythology in software, medicine, law, etc. - why do it here?
        
         | throwaway2245 wrote:
         | The parent link is a journalistic version of the information,
         | not the scientific paper(s) with the evidence.
         | 
         | Besides, the closest equivalent in software is:
         | 
         | If you have ~20 lines of code, written twice with the same
         | function (perhaps crossing multiple functions in the same
         | order), written with identical style and syntax, with maybe
         | some variable names being slightly different.
         | 
         | In a copyright case, would you believe that these originate
         | from different authors?
        
         | darig wrote:
         | You're right, God made the placenta.
        
         | patcon wrote:
         | Former biochemist here. There may be flaws in the study (i
         | haven't read it), but none of what you're gesturing to strikes
         | me as evidence of "jumping to conclusions". A couple thousand
         | basepairs is a row (a fair assumed length for encoding
         | proteins) is plenty enough to draw conclusions about
         | evolutionary provenance, and this is totally common.
         | 
         | For lots of ho-hum reasons that don't require any spectacular
         | justification, you are full of virus DNA -- it's just mostly
         | never mentioned in popsci articles that come under your
         | skeptical lens :)
        
         | sradman wrote:
         | > conclusion: the placenta is the product of that virus. We
         | would never accept that kind of mythology in software
         | 
         | Seems like a very reasonable hypothesis if that virus is a
         | retrovirus [1]:
         | 
         | > Endogenous retroviruses (ERVs) are endogenous viral elements
         | in the genome that closely resemble and can be derived from
         | retroviruses.
         | 
         | > ...not all ERVs may have originated as an insertion by a
         | retrovirus but that some may have been the source for the
         | genetic information in the retroviruses they resemble.
         | 
         | [1] https://en.wikipedia.org/wiki/Endogenous_retrovirus
        
         | flobosg wrote:
         | > Unsubstantiated
         | 
         | Not really:
         | https://www.liebertpub.com/doi/10.1089/088922299309810
        
       | andrewflnr wrote:
       | I'm just realizing that several shark and snake species also give
       | birth to live young, but I don't know whether they have placentas
       | or similar structures. I'm sure they couldn't be homologous to
       | mammal placentas, right? (Certainly not if this article is right
       | about the timeline.) To what extent do viviparous animals
       | converge when it comes to the mother/child interface?
       | 
       | So some sharks have placentas, as mentioned in this article about
       | tiger sharks secondarily losing theirs:
       | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4906603/ I wonder if
       | I'll ever run out of huge, obvious questions I haven't even begun
       | to explore.
        
         | jelliclesfarm wrote:
         | Sharks are viviparous, oviparous and also ovoviviparous.
         | 
         | [..] There are over 500 species of shark living in waters
         | around the world and the majority give birth to live young. The
         | remainder are oviparous, meaning they lay eggs. [..]
         | 
         | [..]Whale sharks (Rhincodon typus) are the largest species of
         | shark. Although these animals produce eggs, they don't lay
         | them. Instead, the young hatch while still in the female's body
         | and are born as miniature adults. This is known as
         | ovoviviparity.[..] In some species, the female will produce
         | unfertilised eggs, which are eaten by embryos. This is known as
         | oophagy ('egg eating') and occurs in species including the
         | shortfin mako (Isurus oxyrinchus) and bigeye thresher sharks
         | (Alopias superciliosus).
         | 
         | Embryos of other sharks survive by feeding on their smaller
         | siblings. This is called intrauterine cannibalism or sometimes
         | as embryophagy ('embryo eating'). This is known to occur in
         | sand tiger sharks (Carcharias taurus).
         | 
         | Placental viviparity occurs in some species of shark - once the
         | yolk sac has been depleted, it attaches to the uterine wall,
         | acting as a pseudoplacenta.[..]
         | 
         | https://www.nhm.ac.uk/discover/do-sharks-lay-eggs.html
        
           | dr_orpheus wrote:
           | Thank you for this link on how sharks give birth. I never
           | thought the subject would be so fascinating.
           | 
           | Also led me to this interesting article on the Basking shark
           | which has an absolutely gigantic mouth for filter feeding
           | plankton.
           | 
           | https://www.nhm.ac.uk/discover/basking-shark-cetorhinus-
           | maxi...
        
             | jelliclesfarm wrote:
             | I remember that! Also whales do that too iirc.
        
         | shellfishgene wrote:
         | Seahorses are also interesting in this regard, not only do they
         | also have internal pregnancy and a placenta-like structure,
         | it's also the males that get pregnant.
        
           | dmos62 wrote:
           | Sorry for asking a simple question, but how do we distinguish
           | sexes? If male seahorses can be pregnant, it's obviously not
           | by which sex gives birth.
        
             | chongli wrote:
             | It's entirely determined by the gametes. Males produce
             | sperm, females produce eggs.
        
               | jessriedel wrote:
               | And the thing that distinguishes eggs from sperm is what?
               | The relative size? (Are there no species where they are
               | roughly the same?) Or that the mitochondria come from the
               | egg?
               | 
               | Edit: Looks like it's merely relative size, and when
               | neither gamete is bigger biologists throw up their hands.
               | Sort of a bummer that there isn't a more robust
               | definition.
               | 
               | https://en.wikipedia.org/wiki/Isogamy
        
               | chongli wrote:
               | The relative size but also the structure and the process
               | of fertilization. The sperm enters the egg, not the other
               | way around. Mitochondria come from the egg, yes.
               | 
               | Also note that sperm vary in shape. Mammalian sperm have
               | the familiar tadpole shape with a flagellum for swimming.
               | Other species, such as nematodes, have ameboid sperm
               | which move along surfaces rather than swimming freely.
        
               | jessriedel wrote:
               | > The sperm enters the egg, not the other way around.
               | 
               | I think this is wrong. My understanding is that the sperm
               | cell membrane fuses with the egg cell membrane, forming a
               | single container. The haploid nucleus of the sperm and
               | the haploid nucleus of the egg then fuse. This processes
               | is by no means fully symmetric (the egg has a tough
               | coating on its cell membrane that must be dissolved by
               | the sperm through the Acrosome reaction), but there is
               | also no time when the sperm cell (delineated by its
               | membrane) is _inside_ the egg cell.
               | 
               | https://en.wikipedia.org/wiki/Acrosome_reaction
               | 
               | My point was not that there aren't many correlated
               | asymmetries between eggs and sperm _in particular parts
               | of the phylogenetic tree_ (like mammals) that can be used
               | for distinguishing them. My point was that there seems to
               | be no fundamental asymmetry that applies to all two-sex
               | sexually reproducing organisms; rather, there is a
               | continuum of degree of gamete dimorphism that ends at
               | organisms where there is no principled distinction
               | between sperm and egg (isogamy).
        
               | f6v wrote:
               | I red this in some book I forgot the name of, so I can't
               | cite anything. But it was explained that female strips
               | everything except for the DNA from sperm. This way
               | there's minimal risk of infecting the egg with the
               | pathogens the sperm can carry. I'm not sure if it's true
               | just for humans or other organisms as well.
        
             | goalieca wrote:
             | I am not a biologist but what I remember from biology is
             | that female seahorses have the eggs. Sexual reproduction
             | happens when two haploid cells combine and the sex is
             | determined based on this system.
        
       | chrisma0 wrote:
       | Retroviruses and our coexistence with them is fascinating to me.
       | 
       | Fun fact: "About 8 percent of human DNA comes from viruses
       | inserted into our genomes in the distant past, in many cases into
       | the genomes of our pre-human ancestors millions of years ago."
       | https://newsroom.uw.edu/news/genes-%E2%80%98fossil%E2%80%99-...
       | 
       | Endogenous retrovirus Wiki page:
       | https://en.wikipedia.org/wiki/Endogenous_retrovirus
        
         | vbezhenar wrote:
         | Just a wild thought: if aliens wanted to change a genome of
         | some species, what are the chances they would construct viruses
         | to do that? AFAIK CRISP uses something similar.
        
           | irjustin wrote:
           | Ah is that what's in the black goo?
        
           | remram wrote:
           | That would probably only work if it gave the altered species
           | a significant advantage (or if you had a system to detect and
           | penalize/eliminate individuals depending on their genome, at
           | scale).
        
             | koeng wrote:
             | Or you gene drive them.
        
             | [deleted]
        
             | klyrs wrote:
             | At this point in time, do you really think that viruses are
             | incapable of sweeping the globe and infecting a significant
             | fraction of humanity, if they don't provide a benefit to
             | the host?
        
               | remram wrote:
               | The parent was more specific and asked about _changing a
               | species 's genome_. Infecting everyone does not lead to a
               | change in genome if they die (or fight it off).
               | 
               | Assuming a low percent of the infected get their genome
               | changed or produce offspring with altered genome, those
               | don't take over.
        
         | [deleted]
        
         | studiecomput wrote:
         | Another wild thought: Is it possible that the solution for
         | harmful retroviruses, like HIV, are retroviruses itself? If
         | retroviruses can overwrite or fuse with our DNA, can't we
         | overwrite it back by making a retrovirus ourselves?
         | 
         | I'm not familiar with this topic at all, but it's super
         | interesting.
        
           | matheusmoreira wrote:
           | The problem with pathological viruses is they take over the
           | cells themselves and make them fabricate more viruses until
           | they burst. In these cases there is no living cell left to
           | reprogram.
           | 
           | In the case of HIV it's even worse since it targers certain
           | immune cells. It will eventually kill most of them if it's
           | allowed to replicate unchecked, crippling its host's immune
           | response.
        
       | bolangi wrote:
       | The baby's cells are not wholly walled off from the mother's
       | system. Like the best parasites, babies suppress their mother's
       | immune system when it comes to their own cells.
        
       | greyface- wrote:
       | The neuronal gene Arc, which is key to learning and long-term
       | memory in mammals, also has retroviral origins.
       | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5884693/
        
       | johnnujler wrote:
       | Every thing about life is so fascinating. I have always wondered
       | how viruses have persisted for so long if they need a host to
       | survive and it took us millions of years to go from single celled
       | to multicellular. I wish there was a way to know everything and
       | become good at everything. :/
        
         | saagarjha wrote:
         | That would certainly be nice in some ways, but then you'd
         | deprive yourself of the joy of learning.
        
         | olau wrote:
         | I think the plain answer is that if they didn't, you wouldn't
         | know about them. Just like all other parasites. In some sense,
         | we're all parasites on plants, that in turn feed on the energy
         | delivered by the giant fusion reactor in the middle of our
         | solar system.
         | 
         | In the case of viruses, remember that there are viruses for
         | much simpler organisms, like bacteria. And yes, you can use
         | those to treat bacterial infections.
        
           | webmaven wrote:
           | _> In the case of viruses, remember that there are viruses
           | for much simpler organisms, like bacteria. And yes, you can
           | use those to treat bacterial infections._
           | 
           | Those are called bacteriophages (a misnomer, since they don't
           | actually eat bacteria).
           | 
           | I have a theory that bacteriophages originated as a
           | biochemical weapon for inter-bacterial competition.
           | 
           | If you think about it, the ability to produce packets that
           | target and penetrate a competitor's cellular wall and inject
           | a payload is pretty useful. Payloads could be as simple as a
           | toxin to start.
           | 
           | From that point, you could have stepwise improvements for
           | deliverables that disrupt reproduction in the target (for
           | example by cutting apart DNA strands), by inserting junk
           | genetic material to evade self repair mechanisms, by
           | inserting or removing specific genetic sequences to create
           | other vulnerabilities, that insert the specific genes to make
           | copies of the delivery system and various payloads (this is
           | useful even if the 2nd gen copies are poor and don't include
           | those same genes), and then finally a fully self-reproducing
           | package that can spread exponentially.
           | 
           | At that point the 'weapon system' can evolve independently,
           | and indeed co-evolve with it's target/host to (probably)
           | jointly outcompete other species including the originating
           | species.
           | 
           | Even prior to full self-reproduction, proto-viroids might act
           | as a horizontal gene transfer mechanism that can exhibit
           | familiar 'selfish gene' patterns and mediate various feedback
           | loops between bacterial species. After 'escape' any species
           | remaining with proto-viroids mechanisms would likely be
           | parasitized and bootstrapped into actual viruses through
           | competition and crossovers, or have those mechanisms
           | suppressed into remnants indistinguishable from endoviruses
           | (presuming endoviruses can even be identified in organisms as
           | simple as bacteria).
           | 
           | An arms-race of proto-viroid attack vectors might also be the
           | antecedents of and/or the driving force behind the need for
           | various organelles that distinguish the more complex
           | eukaryotes from bacteria.
        
         | ChrisMarshallNY wrote:
         | _> I wish there was a way to know everything and become good at
         | everything._
         | 
         | There must be some way to do it, because I constantly encounter
         | people on the Internet, that know everything, and are good at
         | everything.
         | 
         | I can't get any of them to tell me how they do it, though...
        
           | johnnujler wrote:
           | I wouldn't say everything, but I have encountered such people
           | too. Extremely knowledgeable and always curious. It feels as
           | if these guys somehow have more energy to expend than most of
           | us. On the contra, I get burnt-out pretty quickly when I try
           | to push myself beyond an arbitrary threshold which I have
           | never been able to measure.
        
         | TeMPOraL wrote:
         | Viruses are ultimately bits of genetic code wrapped in a shell
         | and injection mechanism. IANAB, so this is pure conjecture,
         | but: it wouldn't surprise me if it turned out that viruses are
         | a kind of degenerative state - something evolution may just
         | spit out as it makes mistakes trying to improve on cells. If
         | that's the case, then viruses may exist simply because they are
         | a waste product of natural selection of more complex life.
        
           | mrunkel wrote:
           | This implies that evolution has a goal and that we are that
           | goal. This shows a fundamental misunderstanding of evolution
           | of natural selection that is common.
           | 
           | Who is to say that viruses won't be the end result of life on
           | the planet earth?
           | 
           | Complex life <> more evolved life. It's just differently
           | evolved.
        
             | TeMPOraL wrote:
             | I know that evolution doesn't have a goal. I may have
             | antropomorphosized it too much, but my goal was to follow a
             | sort of temporal/casual trail that we find interesting.
             | 
             | The way I imagine my idea is that, if you pick a species
             | and its interesting descendants, and order on a timeline
             | like such:                 A --> B --> C --> D
             | 
             | What really happens is more like:                 [bunch of
             | other spinoffs]         ^         |       A --> B --> ...
             | 
             | And that some of those spinoff could be viruses. Imagine a
             | mutation to A causes a bunch of functionality in the
             | organism to shut down (and in subsequent generations
             | disappear), while leaving a viable organism. For a
             | sufficiently uncomplicated A, the result of such mutation
             | could be a bundle of genes wrapped in a shell with an
             | injection mechanism. That's a virus.
        
           | bdjfkrk wrote:
           | There are some hypotheses that viruses are involved in the
           | origin of life.
           | 
           | https://www.frontiersin.org/articles/10.3389/fmicb.2019.0052.
           | ..
        
       | rocqua wrote:
       | Wait, so placenta's existed before this virus gave us the ability
       | for them to work?
       | 
       | I would have guessed that the virus imparted the DNA at some
       | earlier point, and that DNA helped a placenta evolve.
        
         | shellfishgene wrote:
         | More specifically, the gene that enables syncytiotrophoblasts
         | to do what they do enabled placentas to be compatible with an
         | adaptive immune system. So the evoution of the placenta needs
         | to be seen in the immune system context, a more simple immune
         | system may not have a problem with a non-self embryo in the
         | body. So the virus gene could be one of the factors that
         | enabled a proto-placent to evolve along an adaptive immune
         | system. [Note this is pure speculation, I haven't read up on
         | the evolutionary timescales of either.]
        
         | _Microft wrote:
         | There seem to be a lot of different levels of maternal support
         | for unborn offspring, ranging from ,,shelter" by carrying eggs
         | until they hatch to full life-support like mammals offer it.
         | 
         | https://en.m.wikipedia.org/wiki/Viviparity
        
       | cat199 wrote:
       | nah, it was totally aliens.
       | 
       | source: i too can make things up and claim 'scientz'
        
       | qiqing wrote:
       | Relevant: egg laying mammals
       | 
       | https://en.wikipedia.org/wiki/Monotreme?wprov=sfla1
        
         | emmelaich wrote:
         | also .. https://en.wikipedia.org/wiki/Parthenogenesis
         | 
         | Some sharks can have so-called 'virgin' births.
        
       | 29athrowaway wrote:
       | Sometimes there can be an immune response towards the baby. See:
       | https://en.wikipedia.org/wiki/Hemolytic_disease_of_the_newbo...
        
         | rsynnott wrote:
         | Yes, quite commonly, really. Evolution tends to optimise for
         | 'good enough' solutions, not perfect ones.
        
       | godlovestrump wrote:
       | This is very similar to the story of Jesus as his mother, Mary
       | was a virgin.
       | 
       | So they don't need to spend all that tax payer dollars on
       | researching this.
       | 
       | God made man. End of story.
        
       | RandomWorker wrote:
       | This is also described in a recent book called "world of
       | viruses." Worth reading, as there is way more fascinating things
       | I learned about viruses reading this book. Like that there are
       | super big viruses the size of bacteria that are the closest point
       | between a cell and a virus, a fascinating discussion about if
       | viruses are dead or alive, and that there are 55 types of viruses
       | found in a random blue birds that could hop in to humans like the
       | West Nile virus did not so long ago.
        
       | est31 wrote:
       | If you want to know more, I recommend the virology lectures from
       | Vincent Racianello: https://www.youtube.com/watch?v=F0n8SeeC4II
        
         | type0 wrote:
         | This Week in Virology and their other podcasts are also greatly
         | recommended! https://www.microbe.tv/
        
       | xattt wrote:
       | The article cited in the post:
       | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6177113/
        
       | jonplackett wrote:
       | So are we all going to be superhuman in 100,000 years thanks to
       | COVID or does this only happen with retroviruses?
        
         | pantalaimon wrote:
         | Was #DOScember the result of a Retrovirus?
        
       | KuhlMensch wrote:
       | I like to hope, if I am ever afflicted by a virus; the inevitable
       | distress of "A virus? woe is me" will be tempered by the pithy
       | thought, "A virus whence is me".
        
         | buran77 wrote:
         | Unfortunately trying to get something useful from a viral
         | infection is almost like trying to get bitten by a radioactive
         | spider in order to get superpowers. The problem is that as
         | useful as those new "features" may be, they always need many
         | generations and many more mutations to be integrated and turn
         | into something practically useful. In the meantime you would at
         | best have to live with a painful spider bite and some radiation
         | poisoning.
        
           | hypertele-Xii wrote:
           | The best time to plant a tree is 20 years ago.
        
             | xattt wrote:
             | The best time to get retroviral gene integration is
             | hundreds of millions of years ago.
        
               | dmos62 wrote:
               | Best time to get in trouble is when you're already out of
               | it.
        
             | simonh wrote:
             | The second best time is now :)
        
           | lundswe wrote:
           | We have to hope for a real vaccine offer and behave
           | responsibly.
           | 
           | Not hoping to be in a distopic yet magic world.
        
       | xkgt wrote:
       | For anyone fascinated by this topic, the book I, Mammal[1] by
       | Liam Drew is highly recommended. A whole chapter is dedicated to
       | the importance of placenta in evolution of mammals, along with
       | other chapters on other mammalian features like lactation, hair,
       | locomotion, homeothermy etc.,
       | 
       | [1] https://www.goodreads.com/book/show/30038815-i-mammal
        
       | fastaguy88 wrote:
       | I think this article is a bit misleading. The placenta did not
       | evolve from an ancient virus. A protein found in primate
       | placentas (but, interestingly, not found in other placental
       | mammals) is clearly related to endogenous retrovirus proteins. (I
       | do not think that HERV and HIV have much to do with each other --
       | they are very different viruses). But it is pretty interesting
       | that primates started using this protein relatively late in
       | mammalian evolution.
        
       | _Microft wrote:
       | As much as I would like to discuss but I am on my phone and
       | typing there just sucks. The topic is a real rabbit hole in a
       | positive sense.
       | 
       | Either way, I would like to thank user dragosmocrii who lead me
       | to this article via their comment at
       | https://news.ycombinator.com/item?id=25655272
        
       | vagrantJin wrote:
       | This makes me wish I paid more attention in my virology and
       | Recombinant DNA classes. Reminds me of how strange biology
       | actually is.
        
       | kelchqvjpnfasjl wrote:
       | Is this horizontal gene transfer?
       | 
       | https://en.wikipedia.org/wiki/Horizontal_gene_transfer
        
       | sradman wrote:
       | Magnificent. The placenta uses a protein named syncytin [1] to
       | attach to the cells of the uterus. This protein is expressed by a
       | retrovirus that was integrated into animal DNA over 100 million
       | years ago.
       | 
       | This reminds me of Lynn Margulis' discovery that mitochondria and
       | chloroplasts are ancient bacteria incorporated into the cell [2].
       | 
       | [1] https://en.wikipedia.org/wiki/Syncytin-1
       | 
       | [2]
       | https://en.wikipedia.org/wiki/Lynn_Margulis#Endosymbiosis_th...
        
         | jacquesm wrote:
         | I don't recall where I read it but I recall that the nucleus of
         | a cell started out as a captive bacterium.
        
           | koeng wrote:
           | Not likely for nucleus -
           | https://doi.org/10.3389/fmicb.2020.571831
           | 
           | Gemmata obscuriglobus is pretty interesting, and one could
           | imagine how you go from it to nucleus
           | https://en.wikipedia.org/wiki/Gemmata_obscuriglobus
        
             | jacquesm wrote:
             | Interesting, thank you!
        
       | jgilias wrote:
       | It is also being researched how endogenous retroviruses are part
       | of aging. The very rough idea being that at some point long in
       | past a retrovirus became endogenous and provided a pathway for
       | aging increasing the evolutionary rate of that organism, which
       | would then out-compete most of the immortal organisms with time.
       | 
       | Something like:
       | 
       | https://pubmed.ncbi.nlm.nih.gov/20346965/
        
         | pps wrote:
         | That's incredibly interesting! Do you know some (pop)science
         | books that could help learn more about viruses? I found two
         | that sound good from description: "Viruses: A Very Short
         | Introduction" by Dorothy H. Crawford and "A Planet of Viruses"
         | by Carl Zimmer. Would you recommend any of these or something
         | else?
        
           | erentz wrote:
           | It's not a science book, but this did bring to mind an
           | enjoyable sci-fi book by Greg Bear called Darwin's Radio, for
           | reasons that'll be obvious:
           | https://en.wikipedia.org/wiki/Darwin%27s_Radio
        
           | a11r wrote:
           | Not a book, but prof. Vincent Racaniello offers free
           | courses[1] and has great youtube videos.
           | 
           | [1]https://www.virology.ws/course/
        
           | f6v wrote:
           | Red queen gives some perspective on evolutionary arms race
           | between hosts and pathogen. Virus is a piece of genetic
           | material, so to understand a virus one needs to understand
           | how a gene evolves.
        
           | jgilias wrote:
           | I'm not really in a position to suggest a good book on
           | viruses. I found out about this from a pop-sci book on latest
           | research on aging and longevity.
           | 
           | When it comes to viruses though, there's one more very
           | fascinating hypothesis. That the cell nucleus itself was once
           | actually a virus that took over some bacteria to do its
           | bidding.
           | 
           | https://en.wikipedia.org/wiki/Viral_eukaryogenesis
        
         | blago wrote:
         | I think immortal is the wrong word here. All organisms die. If
         | it's not aging, then decease and predators will do it.
        
           | remram wrote:
           | I'm not aware of a context where immortal refers to organisms
           | that can't be killed by accidents and predators. In mythology
           | and novels alike, vampires, gods, elves, ..., are all called
           | immortal and still can be killed.
        
             | welfare wrote:
             | It's called Biological Immortality[1] and there are a few
             | examples of animals that are considered immortal.
             | 
             | [1] - https://en.wikipedia.org/wiki/Biological_immortality
        
               | lsiunsuex wrote:
               | I thought crocodiles or alligators (forget which one)
               | were immortal and they tend to die only because they get
               | so big and can't eat enough to maintain life eventually.
               | But, they're not on this list?
        
           | jjk166 wrote:
           | Biological immortality is the technical term for organisms
           | which do not die unless killed, or more accurately where rate
           | of mortality from senescence does not increase with
           | chronological age.
        
             | ckosidows wrote:
             | I thought the term was negligible senescence?
        
               | jjk166 wrote:
               | They're similar but distinct concepts. Negligible
               | senescence means after a point aging doesn't negatively
               | affect the organism. They don't lose reproductive
               | capability or experience functional decline. Imagine
               | being 20 forever.
               | 
               | Biological immortality means after some point mortality
               | rates don't increase with age - you can still grow old,
               | it just won't directly kill you. Biologically immortal
               | organisms don't have a max lifespan, if they're lucky
               | they can just keep on going, but they may be dramatically
               | more feeble than their younger counterparts.
        
             | blago wrote:
             | Ah, I didn't know that. Thanks.
        
         | BurningFrog wrote:
         | Since I had to look it up...
         | 
         |  _endogenous_
         | 
         | - having an internal cause or origin.
         | 
         | - growing or originating from within an organism.
        
           | flobosg wrote:
           | To put it into context:
           | https://en.wikipedia.org/wiki/Endogenous_viral_element
        
         | phkahler wrote:
         | >> The very rough idea being that at some point long in past a
         | retrovirus became endogenous and provided a pathway for aging
         | increasing the evolutionary rate of that organism, which would
         | then out-compete most of the immortal organisms with time.
         | 
         | No virus needed. Humans are currently (or were very recently)
         | under enormous evolutionary pressure to get smarter. The
         | ability to adapt is likely itself a trait as you suggest, but
         | it makes sense that it can vary over time as needed depending
         | on environmental factors.
        
       | scotty79 wrote:
       | Weird how antivaxxers use this obscure bit of knowledge to get
       | scared about similarity of covid S-protein to syncytin and immune
       | response to covid vaccine (why not covid itself?) making
       | pregnancy harder or impossible.
        
         | Karawebnetwork wrote:
         | Some context: https://sciencebasedmedicine.org/it-was-
         | inevitable-that-anti...
         | 
         | Please do not mistake this comment as antivaxx nonsense, the
         | article linked discredits both the theory and the scientists
         | who started it all.
        
           | scotty79 wrote:
           | Thank you! Have you found anything that would indicate any
           | level of actual similarities between S protein and syncytine?
           | Beyond both of them being of virus origin and starting with
           | letter S?
           | 
           | I couldn't find anything stronger than "german doctors say"
           | which means nothing.
        
             | Karawebnetwork wrote:
             | > I couldn't find anything stronger than "german doctors
             | say" which means nothing.
             | 
             | That's all there is to it.
        
               | scotty79 wrote:
               | Yes. Sorry. I asked before I finished reading the article
               | you linked to.
        
       | f6v wrote:
       | What's fascinating is that genome is highly dynamic. The
       | transposons rearrange themselves all the time and are believed to
       | be remnants of ancient viruses. And there's probably many more
       | pieces of DNA which are domesticated viruses. Alu element comes
       | to mind, which is the most common transposable element in human
       | genome and probably has a role in regulating gene expression.
        
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