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8% of Your DNA Comes From a Virus 478

An anonymous reader writes "About 8 percent of human genetic material comes from a virus and not from our ancestors, according to an article by University of Texas at Arlington biology professor Cédric Feschotte, published in the Jan. 7, 2010 issue of Nature magazine."
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8% of Your DNA Comes From a Virus

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  • Useful? (Score:5, Interesting)

    by Kolie ( 1012967 ) on Thursday January 07, 2010 @11:21AM (#30682660)
    Is any of that DNA in use or are those parts dormant? What effect do these modifications have on us beyond the initial use of replication and further propagation of viruses?
  • by IronDragon ( 74186 ) on Thursday January 07, 2010 @11:23AM (#30682684) Homepage

    This is a fairly good little video that explains how RNA monomers end up naturally forming into longer polymer chains. Roughly 95% of our DNA is basically crap that only exists because at some point in the past, it was better at copying itself.

  • Poor Summary (Score:5, Interesting)

    by Dr. Eggman ( 932300 ) on Thursday January 07, 2010 @11:28AM (#30682768)
    The real news here doesn't appear to be that endogenization has occured through our past (OK, maybe the 8% number is news; I don't know about the numbers...) but instead that a virus, bornavirus, is displaying this property. This is news because bornaviruses are not retroviruses (previously the only know virus-types to produce endogenous copies.) Furthermore, the article seems to suspect that this virus may have ties to the schizophrenia and mood disorders...
  • Re:Useful? (Score:5, Interesting)

    by Wonko the Sane ( 25252 ) * on Thursday January 07, 2010 @11:29AM (#30682788) Journal

    Back with this story [] first came out I remember reading that DNA introduced by virus is thought to have given us the genes that allow the formation of placenta, which gave rise to mammals.

    All the articles from around that time seem to be locked away behind paywalls now.

  • Re:Bible Code? (Score:4, Interesting)

    by SharpFang ( 651121 ) on Thursday January 07, 2010 @11:32AM (#30682836) Homepage Journal

    Not necessarily.
    A virus infects a human. It gets to infect the sperm or egg cell. Insignificant part of genetic code gets replaced.
    A child is born with -all- its cells containing the virus-originated code.

    Of course the replaced part will be several genes at most, but if the mutation is insignificant or positive, it will remain in all the offspring. Meanwhile this may repeat any number of times and will be perpetuated through ages.

    If a defect of lacking one whole chromosome is non-lethal (Down's syndrome), a minor damage to your genome has a really good chance of not affecting your offspring at all.

  • Mammals (Score:5, Interesting)

    by Anonymous Coward on Thursday January 07, 2010 @11:32AM (#30682858)

    Google for placenta and endogenous (as in endogenous virus). The placenta uses a lot of viral code, to the extent that it might be more virus than anything else. It also sheds a lot of viruses. The placenta is almost a different life form.

    BTW, the Wikipedia entry shows that the "8%" number was known as long as 6 years ago. []

  • Re:Useful? (Score:2, Interesting)

    by oh_my_080980980 ( 773867 ) on Thursday January 07, 2010 @11:41AM (#30682992)

    The researcher was looking at the Bornavirus (BDV) and its association with Schizophrenia. So yes, it's active and yes it has an effect on us.
  • Re:Poor Summary (Score:1, Interesting)

    by Anonymous Coward on Thursday January 07, 2010 @11:45AM (#30683058)

    You're right, the linked article the summary is based on is an opinion piece about this article [], and it's not about the proportion of virus DNA in our genome.

    The real news from the journal is: "Here we show that elements homologous to the nucleoprotein (N) gene of bornavirus exist in the genomes of several mammalian species, including humans, non-human primates, rodents and elephants...Our results provide the first evidence for endogenization of non-retroviral virus-derived elements in mammalian genomes and give novel insights not only into generation of endogenous elements, but also into a role of bornavirus as a source of genetic novelty in its host."

  • Re:Mammals (Score:5, Interesting)

    by MightyMartian ( 840721 ) on Thursday January 07, 2010 @12:25PM (#30683700) Journal

    ERVs have been known about for some time and are, in fact, one of the "killer" evidences for evolution. You can actually trace lineages with these genes, and they are useful for dating the splits between related lineages. For instance, chimps and humans share more ERVs than, say, humans and baboons. It's difficult to support that observation via Creationism, unless you proclaim the insipid "that's the way God wants it", but evolution explains it very neatly.

  • Re:Bible Code? (Score:3, Interesting)

    by smellsofbikes ( 890263 ) on Thursday January 07, 2010 @12:47PM (#30684028) Journal
    What matters here is statistically significant matches. Pretend for a second that DNA is C code. If you're reading a long stretch of code and suddenly run across a #define <virus.h>; void main(void) { int virus, x; ... and so forth, you know that you're looking at a chunk of code that's not supposed to be there and you know that everything between that { and the matching } is part of the stuff that's not supposed to be there -- and it might be several kilobytes of wrong DNA. In the case of genes, the #define/main stuff is a group of genes known as promoters and repressers and stuff like that, which are preambles that provide a control system for the DNA replication machinery so it can tell where to start reading and when to replicate a section, and most viruses have similar setups since they have to fool the cellular machinery into thinking it's replicating its own DNA.

    The complication comes in that DNA replication is lossy, but evolution is conservative. So if random changes creep into critical stretches of DNA, called conserved sequences, bad things will happen to the cell. If changes creep into DNA that isn't currently functional, as is the case with endogenous retroviruses or other viral material that got stashed in but didn't end up producing a virus for whatever reason, those changes stick around since the DNA isn't expressed: there's no evolutionary pressure to maintain the code, so it slowly degrades.

    The rate at which it degrades is reasonably constant. DNA polymerases have a measurable, consistent error rate. So your old viral code slowly accumulates errors, but it's still recognizeable: you know what you're seeing when you read #defne <virus.h>. A nice side-effect of this is that, since the replication error rate is fairly constant, you can also tell roughly how long a chunk of viral material has been in the DNA by the number of errors it has accumulated compared to a reference genome.

    So as a long answer to a short question, you don't look for six-base correlation, you look for a 95% correlation over several thousand sequential bases before you announce you've found a virus-like pattern.

  • Re:Revelation (Score:5, Interesting)

    by ElectricTurtle ( 1171201 ) on Thursday January 07, 2010 @12:51PM (#30684112)
    To be pedantic, the difference between humans and animals is usually called reason, but in fact it's probably more specific if less poetic to call it 'problem solving'. Animals don't 'live in equilibrium' per se because that implies that they know what they're doing, as though they're thinking 'oh... I'll eat exactly this much and no more because that will mess things up!' Pfff I'll bet somewhere there's some green whackjobs who think that's exactly the romantic notion going through the brains of animals. (In fact, there are predators that kill even after they are full, just to kill. I remember watching a documentary about sea turtles and watching them hatch and try to make their way to the sea, and predatory birds were attacking them, first to eat them, but even after that they just kept killing and leaving the dead baby turtles there to rot.) Anyway, I'm rambling, point is, animals expand as far as they can. They consume as much as they can, whenever and where-ever they can, and reproduce as often as possible. What determines their numbers ultimately are things like the rate at which their consumed resources replenish and the rate at which they otherwise die from predation/disease/accidents/age, not some kind of instinctive population control.

    So the contrast is, an animal, insofar as it thinks, thinks 'I will eat x' and then when x is scarce it thinks 'oh shit there isn't enough x!' Then depending on luck, it dies. Whereas humans think 'I like to eat x' and when x becomes scarce humans think 'well, this sucks, there isn't enough x anymore. Maybe I can eat something else? How about this? Ew. No, not that. How about this other thing? Meh, it's ok. Maybe I can cook it? What things could I do, or do in concert with others, that might restore the natural abundancy of x and/or allow x to be produced in an environment I control?' Yeah. That's why human population keeps growing, moving, adapting, and animals just have to suck it up. They can't solve resource problems creatively.

    (Viruses aren't creative either, they and other micro-organisms just have such fast life cycles that it allows them to find mutations that positively affect their survival at a higher rate. In other words they adapt quickly by chance, humans adapt quickly by decisions.
  • Re:Useful? (Score:5, Interesting)

    by icegreentea ( 974342 ) on Thursday January 07, 2010 @12:54PM (#30684160)
    Apparently a lot of the ERVs (that 8% of our DNA made from retrovirus pieces) get expressed during pregnancy by the fetus. One of the results is that the mother's immune system gets depressed (apparently a lot of HIV-like stuff going on there) that prevents the mother's immune system from killing the fetus. There's probably lots of other fun stuff going on that we don't know about yet. It's actually really cool when you think about it... mammalian childbirth being possible because some immunodepressent virus infected some reptile a long long time ago.
  • Re:Ob. Matrix quote (Score:3, Interesting)

    by nedlohs ( 1335013 ) on Thursday January 07, 2010 @01:22PM (#30684580)

    How is that hypocrisy?

    Raising the dead, walking on water, healing the sick, etc, etc. All can be done* by God as a miracle or by demons as witchcraft. It's not hypocrisy, it's caring about the source more than the action.

    Having another religion is usually punishable, again not hypocrisy just standard religion.

    * According to believers, a set I'm not a member of so I really should stop talking about their business...

  • Re:Ob. Matrix quote (Score:2, Interesting)

    by Impy the Impiuos Imp ( 442658 ) on Thursday January 07, 2010 @01:38PM (#30684840) Journal

    Did you miss the part in the Bible where God beats the crap out of other gods, like Leviathan and the Egyptian Pharoah's god (the whole sticks-into-snakes bit)?

    He is a jealous god, and thou shalt have no other gods before him! And he means real, existing gods, not pseudo-gods like money and power.

    In any case, we know this virus thing is false, since God made everybody, and would hand-craft the DNA, so if it resembles anything in a virus, it's just coincidence.

  • by mollog ( 841386 ) on Thursday January 07, 2010 @01:39PM (#30684848)
    I'll offer proof that this is actually happening; a species that follows human, the Eastern Gray Squirrel, has adapted to cars. Previously, they had an inborn, instinctive behavior of darting in circles when confronted by a danger. This was thought to be an adaptation that helped them escape predation by birds of prey. But this was maladaptive when confronted by a speeding vehicle.

    These days, the gray squirrel runs in a straight line when it is in danger. This is probably good news for birds of prey, but squirrel populations are thriving, so I doubt that birds are as big a problem as cars are.

    I don't doubt that our environment is promoting genetic variations that are compatible with technology. That meme has been suggested before.
  • Re:Bible Code? (Score:5, Interesting)

    by lyml ( 1200795 ) on Thursday January 07, 2010 @01:59PM (#30685128)

    There are 4^3000 (about 1.5*10^1806) different 3000 letter works (if you only have 4 characters). The odds of finding your specific one in a 3 trillion collection of random letters is so small, you can't even imagine how small it is. (approx 1 in 2*10^1794)

    But let's try anyway. Imagine playing the universal lottery. You are supposed to pick one subatomic particle in the entire universe, and if you choose the correct one you get 1 nickle, the odds of winning is about 1 in 10^80, if you were to enter that lottery a billion trillion times a second (10^21) by the time all protons in the universe would have decayed the likelyhood that you would have won even once would be so small that you could not even imagine. Never the less.

    Now imagine playing that lottery one time for each billion trillion times times you look through a different set of random characters (with each set being 3 trillion characters). After having won that lottery, not once, but enough times to build a tower of your nickles 1000 times longer than the circumference of the entire universe the likelyhood of you having found a matching set to your 3000 character set would be so close to 0, that you still can not even imagine how small it is.

    So my guess would be that this virus dna didn't just appear by chance in the dna of humans.

  • Re:Mammals (Score:3, Interesting)

    by Seakip18 ( 1106315 ) on Thursday January 07, 2010 @02:45PM (#30685744) Journal

    I like to think that God was a smart enough creator and made sure there were plenty of chances for early life to get upgrades along the way. Not that God sprinkled magic viruses on chimps and viola, but rather that's how it worked out given a few hundred-million years of life.

    I never quite got how folks think the earth is only 3000 years old and that Dinosaurs never really existed, etc. I'd think it'd be alot easier to explain how creation and evolution fit than deny any evidence of evolution and dinosaurs.

    But, I s'pose it's all choosing which myth and facts to believe in and which to not. Plus, life is a lot more comfortable when your sure what you believe is true and everything contrary is a lie. Religion is just a nice container to organize it all with. topic...

    uh....What'd be even MORE interesting is to compare those divided lineages NOW and see if the viral DNA that originally existed still does in it's original form. If not, what's going to account for the changes(which is like finding a specific needle(s) in a stack of needles)?

  • Re:Bible Code? (Score:3, Interesting)

    by BobMcD ( 601576 ) on Thursday January 07, 2010 @03:10PM (#30686096)

    Genesis shows that Genesis is wrong, so you're kind of going the long-way about proving your point.

    Within that one book, we have two mutually exclusive stories.

    Sequence A: God created all the plants, animals, etc, and then created man 'in his image'

    Sequence B: God created the male human, each type of animal, and then the female human

    These do not compute, and my suspicion is that 'B' is man's hubris altering the original tale.

    Furthermore, there's little in 'A' that precludes evolution, if anything. In fact, man could well have been one of the animals, with the gift of sentience being the act of being 'created in his image'. This also rather neatly answers the question of where Cain's wife came from...

    In short, it is possible for a rational person to read the bible, and science and Christianity are not in fact mutually exclusive, despite being to locate minor nits.

  • Re:Revelation (Score:3, Interesting)

    by Maximum Prophet ( 716608 ) on Thursday January 07, 2010 @04:16PM (#30686896)

    In fact, there are predators that kill even after they are full, just to kill. I remember watching a documentary about sea turtles and watching them hatch and try to make their way to the sea, and predatory birds were attacking them, first to eat them, but even after that they just kept killing and leaving the dead baby turtles there to rot.

    A pure animal whose actions are controlled by evolution of instinct, would stop killing to preserve the food supply. People killed the plains buffaloes just because they liked killing them, and to deny resources for the native Americans.

    Of course, there may be a evolutionary advantage for the birds to kill the baby turtles. They might be a common food, and killing extra turtles might reduce competition for that food supply. Alternately, killing the extra baby turtles might actually increase the supply of adult turtles by weeding out the weak. Killing certain baby turtles might actually increase the bird's food supply in the long run.

  • Re:Ob. Matrix quote (Score:3, Interesting)

    by hairyfeet ( 841228 ) <> on Thursday January 07, 2010 @05:19PM (#30687680) Journal

    I don't think Bill and Sam were anything alike at all. Sam was an ex-preacher and a showman, and while he would do the occasional dark bits he would always lighten them up by going over the top. Bill OTOH hated hypocrisy in all its forms and you could tell didn't really like the bullshit and insanity he saw around him every day. He was MUCH more dark in his humor and very acidic in his tone.

    What Bill and Sam sadly have in common is the fact that we haven't had any really thought provoking comics since they passed. But I would say their individual styles are really very different from each other. Sam was more playful, Bill much more angry and dark.

  • Re:Ob. Matrix quote (Score:2, Interesting)

    by MBGMorden ( 803437 ) on Thursday January 07, 2010 @05:35PM (#30687860)

    Virtually every Christian branch believes it to be symbolic, and I'd wager that the vast majority of Catholics regard it as such too, even if the literal interpretation is "official church doctrine". Just think of it like those left over laws you find on books. In my state it's against the law for women to purchase pantyhose on Sunday or for her to be on top during intercourse. Nobody CARES and the law is ignored, but it remains on the books.

    From the Catholics I've spoken to, Transubstantiation is much the same. Technically "official", but none of them believe it anymore.

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