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The Role of Retroviruses in Human Evolution

mhackarbie writes "The current edition of the New Yorker magazine has up a story about endogenous retroviruses in the genomes of humans and other species. Although researchers have known about such non-functional retroviral 'fossils' in the human genome for some time, the large amount of recent genomic data underscores just how pervasive they are, in a compelling tale that involves humans, their primate cousins, and a variety of viral invaders. Some researchers are even bringing back non-functional viral remnants from the dead by fixing their broken genes."

14 of 133 comments (clear)

  1. Re:Bringing back the dead? by Anonymous Coward · · Score: 5, Funny

    Zombie viruses, huh? Now might be a good time to take stock in really tiny shotguns.

  2. Re:Oh no! by Dr.+Eggman · · Score: 4, Interesting

    Obviously if enough individuals survived with cells reproducing its DNA containing the retrovirus for it to become a species-wide "fossil" it was either not very harmful or possibly even beneficial to our ancestors. You might be able to make the case that perhaps we have since lost the ability to combat these retroviruses, but then we must consider the possibility that in some individuals these portions of dormant virus data have been reactivate naturally. If this has occurred and we are indeed now ill equipt to fight it, then it would have been observed as some disease and possibly classified as a genetic disorder. Who knows, by reactivating these, we have discover the cause, and subsequently the cure (as obviously we naturally beat it once) to some terrible genetic malady!

    --
    Demented But Determined.
  3. The thing about retroviruses... by Anonymous Coward · · Score: 5, Funny

    See the thing about retroviruses is that once they work their way into the genome, they begin to do wack things. They predispose the person to wear bell bottom geans, listen to funk music, wear tube socks, and any number of out of fashion things. They begin to force the person to speak in archaic manners, eg "Thou hast been up intowards my grill!" So I think it's safe to say that we need to eliminate retroviruses as a mechanism of mutation. There comes a time to let certain things go.

  4. Hmm by pclminion · · Score: 5, Interesting

    How do we know the the retrovirus genome didn't originate with the hosts themselves? Did these viruses evolve truly independently, or might they have started out as fragments of genetic code from some larger organism which somehow escaped and became self-sufficient?

    In other words, when we look at the human genome and say, "This is riddled with retroviruses!" is it not possible that the retroviruses were actually there all along, and only later became able to leave the parent cell and operate independently?

    Are retroviruses actually just chunks of "rebel DNA" from our own genome, or possibly from some other species?

    1. Re:Hmm by Harmonious+Botch · · Score: 4, Interesting

      That is a damn good question.

      A 'rebel DNA leaving home' must have happened at least once, in some species, otherwise how could viruses exist? They seem way too complex to have happened by chance, and they can't evolve until they are complex enough to infect.

    2. Re:Hmm by cpricejones · · Score: 5, Interesting

      To understand this, you can do sequence comparisons between retroviral genes and our own genes. For example, retroviruses have an enzyme called reverse transcriptase. This enzyme is a type of polymerase. We have many polymerases in our body, and if RT developed from one of them, then there would be very substantial sequence similarity. This is one way to figure out what proteins do if you do not know their function. You compare their amino acid sequence to other known proteins and see if they are similar. This is very common, and it is how researchers establish relationships between retroviruses to understand how they evolve. For example, HIV is a member of the subgroup of retroviruses called lentiviruses, and these viruses have many things in common. HIV has a cousin called SIV (simian immunodeficiency virus) that is very similar. A really good reference is Coffin, RETROVIRUSES, from Cold Spring Harbor Press.

    3. Re:Hmm by fm6 · · Score: 4, Informative

      You're not the first to have that thought. It was part of the premise of Greg Bear's SF novel, Darwin's Radio. He, in turn, got the idea from various scientists, cited in the back of the book. (Sorry, no copy at hand.)

  5. Re:Bringing back the dead? by skeftomai · · Score: 4, Interesting

    Are viruses even alive in the first place?

  6. Re:Bringing back the dead? by Oktober+Sunset · · Score: 4, Funny

    Either way, lawyers die, which shows there is no downside meddling in genetic engineering.

  7. Cambrian explosion? by Tablizer · · Score: 4, Interesting

    Such viruses may be responsible for the Cambrian Explosion. A new kind of virus may have helped "share good ideas" like eyes, nervous systems, enzymes, etc. between different species of early animals. This may have propelled evolution by allowing life to mix and match instead of each branch having to reinvent stuff from scratch.

  8. Re:Bringing back the dead? by seededfury · · Score: 4, Informative

    "Viruses and aberrant prion proteins are often considered replicators rather than forms of life, a distinction warranted because they cannot reproduce without very specialized substrates such as host cells or proteins, respectively.."

    Life

  9. Two SciFi novels I recommend by ridgecritter · · Score: 5, Informative

    that have emergence of HERVs at the core of their plotlines are Darwin's Radio and Darwin's Children, by Greg Bear. Good reads, both.

  10. Next up: by Lost+Penguin · · Score: 4, Funny

    Umbrella Corporation unavailable for comment.

    --
    I am the unwilling control for my Origin.
  11. Re:Reactivated retroviruses by GwaihirBW · · Score: 5, Informative

    Unfortunately viruses don't compete directly in that potentially harmless way . . . HIV's niche is in your T cells (and others), reproducing itself until the cell explodes. Viruses don't really prey on each other (they are simple RNA injection machines that parasitically use the replication mechanisms of cells they infect for reproduction. The only way for another virus to block it is to just kill all the potential target cells first (not so helpful) or to infect them with counter-RNA that neutralizes that of HIV. The problem with the second is that unless it's also doing dangerous things to you, that helper virus isn't going to be able to spread in order to combat the HIV. It's just not the same as gut bacteria - they take up residence on the limited available real estate, do some digesting of the food you helpfully provide, and defend their turf from unwanted invaders while managing their own reproduction and such, whereas viruses are hijackers by nature.

    --
    "There are four boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order." - Ed Howdershelt