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How the placenta evolved from an ancient virus
- KuhlMensch 6y agoI 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 6y agoUnfortunately 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 6y agoThe best time to plant a tree is 20 years ago.
- lundswe 6y agoWe have to hope for a real vaccine offer and behave responsibly. Not hoping to be in a distopic yet magic world.
- andrewflnr 6y agoI'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/ 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 6y agoSharks 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 https://www.nhm.ac.uk/discover/do-sharks-lay-eggs.html
- dr_orpheus 6y agoThank 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-maximus.html https://www.nhm.ac.uk/discover/basking-shark-cetorhinus-maxi...
- chrisma0 6y agoRetroviruses 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-virus-human-dna-found-be-active https://newsroom.uw.edu/news/genes-%E2%80%98fossil%E2%80%99-... Endogenous retrovirus Wiki page: https://en.wikipedia.org/wiki/Endogenous_retrovirus https://en.wikipedia.org/wiki/Endogenous_retrovirus
- vbezhenar 6y agoJust 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.
- greyface- 6y agoThe 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/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5884693/
- johnnujler 6y agoEvery 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 6y agoThat would certainly be nice in some ways, but then you'd deprive yourself of the joy of learning.
- olau 6y agoI 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 6y ago> 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.
- rocqua 6y agoWait, 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.
- _Microft 6y agoThere 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 https://en.m.wikipedia.org/wiki/Viviparity
- shellfishgene 6y agoMore 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.]
- 29athrowaway 6y agoSometimes there can be an immune response towards the baby. See: https://en.wikipedia.org/wiki/Hemolytic_disease_of_the_newborn https://en.wikipedia.org/wiki/Hemolytic_disease_of_the_newbo...
- rsynnott 6y agoYes, quite commonly, really. Evolution tends to optimise for 'good enough' solutions, not perfect ones.
- _Microft 6y agoAs 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 https://news.ycombinator.com/item?id=25655272
- est31 6y agoIf you want to know more, I recommend the virology lectures from Vincent Racianello: https://www.youtube.com/watch?v=F0n8SeeC4II https://www.youtube.com/watch?v=F0n8SeeC4II
- type0 6y agoThis Week in Virology and their other podcasts are also greatly recommended! https://www.microbe.tv/ https://www.microbe.tv/
- xattt 6y agoThe article cited in the post: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6177113/ https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6177113/
- jgilias 6y agoIt 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/ https://pubmed.ncbi.nlm.nih.gov/20346965/
- blago 6y agoI think immortal is the wrong word here. All organisms die. If it's not aging, then decease and predators will do it.
- jjk166 6y agoBiological 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.
- blago 6y agoAh, I didn't know that. Thanks.
- ckosidows 6y agoI thought the term was negligible senescence?
- jjk166 6y agoThey'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.
- cat199 6y agonah, it was totally aliens. source: i too can make things up and claim 'scientz'
- jonplackett 6y agoSo are we all going to be superhuman in 100,000 years thanks to COVID or does this only happen with retroviruses?
- pantalaimon 6y agoWas #DOScember the result of a Retrovirus?
- xkgt 6y agoFor 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 https://www.goodreads.com/book/show/30038815-i-mammal
- scotty79 6y agoWeird 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.
- Raphmedia 6y agoSome context: https://sciencebasedmedicine.org/it-was-inevitable-that-antivaxxers-would-claim-that-covid-19-vaccines-make-females-infertile/ 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 6y agoThank 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.
- bolangi 6y agoThe 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.
- qiqing 6y agoRelevant: egg laying mammals https://en.wikipedia.org/wiki/Monotreme?wprov=sfla1 https://en.wikipedia.org/wiki/Monotreme?wprov=sfla1
- emmelaich 6y agoalso .. https://en.wikipedia.org/wiki/Parthenogenesis https://en.wikipedia.org/wiki/Parthenogenesis Some sharks can have so-called 'virgin' births.
- vagrantJin 6y agoThis makes me wish I paid more attention in my virology and Recombinant DNA classes. Reminds me of how strange biology actually is.
- kelchqvjpnfasjl 6y agoIs this horizontal gene transfer? https://en.wikipedia.org/wiki/Horizontal_gene_transfer https://en.wikipedia.org/wiki/Horizontal_gene_transfer
- sradman 6y agoMagnificent. 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 https://en.wikipedia.org/wiki/Syncytin-1 [2] https://en.wikipedia.org/wiki/Lynn_Margulis#Endosymbiosis_theory https://en.wikipedia.org/wiki/Lynn_Margulis#Endosymbiosis_th...
- jacquesm 6y agoI don't recall where I read it but I recall that the nucleus of a cell started out as a captive bacterium.
- koeng 6y agoNot likely for nucleus - https://doi.org/10.3389/fmicb.2020.571831 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 https://en.wikipedia.org/wiki/Gemmata_obscuriglobus
- jacquesm 6y agoInteresting, thank you!
- n0rbwah 6y agoFun fact, Syncytin-1 is the syncytin used by primates, other branches of mammals have other forms of syncytins, meaning that the event of being infected by a retrovirus that gives mammals proteins necessary for the placenta happened several times in history following the original event and replaced the original syncytin. (Not sure those proteins are also called syncytins in other mammals but I'm not a biologist so I'm using the limited vocabulary I have)
- kridsdale1 6y ago
- RandomWorker 6y agoThis 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.
- ARandomerDude 6y agoIt'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?
- darig 6y agoYou're right, God made the placenta.
- sradman 6y ago> 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 https://en.wikipedia.org/wiki/Endogenous_retrovirus
- flobosg 6y ago> Unsubstantiated Not really: https://www.liebertpub.com/doi/10.1089/088922299309810 https://www.liebertpub.com/doi/10.1089/088922299309810
- throwaway2245 6y agoThe 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?
- patcon 6y agoFormer 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 :)
- godlovestrump 6y agoThis 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.
- f6v 6y agoWhat’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.
- fastaguy88 6y agoI 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.