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A Human Quasispecies?

October 19, 2011

What if space-faring humans could evolve as a quasispecies? Could this be one way to adapt to a new planet?

A quasispecies is a population of RNA viruses such as HIV (AIDS) or Hepatitis C. RNA genomes have high mutation rates; as high as 10% per base, for HIV. So the vast majority of progeny are “defective” — but: (1) More than one virus particle infects a host cell, so they complement each other’s defects; and (2) some progeny virions have new properties that enable them to infect other tissues, like brain.

Whenever HIV infects a new host, it generates a quasispecies of different virion types. We now consider the quasispecies, with all its variants, as the true evolving unit.

Suppose a form of human with an RNA genome could “infect” a new planet. Would we quickly produce all kinds of offspring who could take advantage of the new world, and complement each other?  Of course, many would die, but then that always happens to new colonists, like the Europeans at Jamestown.

Perhaps more acceptable would be for humans to bring “starter” RNA-life of several types, such as vascular RNA-plants, RNA-invertebrate and RNA-vertebrate animal. TheRNA-vertebrate, for example, would soon generate a quasispecies including swimming forms, crawling forms, flying forms, etc.

  1. October 20, 2011 2:30 am

    RNA would have a hard time supporting cellular life because of the high mutation rate. In single celled life the risk of death because of a lethal mutation would be high, and in multicellular organisms the cooperation between cells would be threatened, which would result in cancer and death.

    Couldn’t DNA-based life work by the same mechanics on a longer time span? In order for evolution to take place you can only have one time of genetic change during a life span, otherwise selection does not work, and the genetic changes aren’t passed on to the next generation.

    So what you want is not necessarily a RNA-vertebrate. What you want are animals with: quick reproductive cycle, huge number of offspring, and large genetic variation between these offspring (but no too large).

    If you could design them you could engineer pre-determined switches for altering the basic body form. They could be environment triggered, or even better environment triggered imprinting through the mother. There should be some degree of randomness so that the species would be forced to spread to new habitats.

    It won’t be as quick as you would like, but then I think space colonisation is going to be the ultimate waiting game. Yes, Ultimate.

    • October 20, 2011 6:01 pm

      Yes, you’re probably right that just increasing the DNA diversity would be more practical than replacing DNA with RNA. And we’ve already evolved animals “rapidly”; look at dogs, for example, all of which breeds have evolved under directed selection by humans over the past few thousand years.

      “Ultimate waiting game” is right–but what kind of humans will have that kind of waiting ability?

      • Petter permalink
        October 28, 2011 5:26 am

        Saw som analysis though (cant remember where) that dog breeding isnt about actual mutations though. The diversification of different types has happened too fast for that. Most of the genes for a chihuahua is already there in the wolf, the difference (as far as I recall) is in the RNA-regulatory mechanisms.
        A designed being should be possible with several traits that can be expressed within a few generations if needed (webbed toes for swimming, massive skeletons for high-gravity environments etc..) Unforeseen needs that are not in the DNA-library will need a lot longer time to develop than the history of dog-breeding might make one assume though.
        Anyone here familiar with the research im reffering to? Otherwise I’ll try to search for it more thoroughly..

  2. October 20, 2011 9:48 am

    Vertebrates typically invest too much in our young (fish less so, mammals more so). Getting to the point where we can reproduce with a high fatality rate is too big a cost.
    We’d need a high likelihood of adequate resources to grow and breed before this sort of strategy would be worthwhile.

    Personally, I’d prefer a directed evolution, possibly based on early tests on lower life forms

  3. October 20, 2011 5:35 pm

    As the others have said, I don’t think RNA would work as useful substrate. Besides which, most of what makes us human is our culture, and that evolves even faster than RNA does. I’d rather work on cultural mutation first, and not worry so much about physical alterations at first.

    • October 20, 2011 6:03 pm

      By “culture” do you mean making machines?
      If we build machine versions of ourselves, like the recent IBM “human” analog (humalog??) that would travel instead–does that count?

      • paws4thot permalink
        October 21, 2011 5:05 am

        IMO our culture is more than just being an advanced tool-making species. It also refers to our social mores, taboos, interactions…

        Other than a few specialised pieces of kit referring to our researches, you and I both use most of the same machines, but an American university professor and a Scottish software engineer (with peripheral tasks) aren’t part of the same culture, although we are in overlapping cultures.

      • October 21, 2011 12:03 pm

        What Paws said. A human without culture (as he defined it) is non-functional. We can’t work without language, clothing, tools, social mores, family interactions, and so forth. Certainly there’s a tradeoff: a fully functional adult takes 20-30 years to be “born” in our current society, a decade after they reach sexual maturity. Conversely, we “evolve” much faster than we would if we only worked with genetic evolution, so we can actually evolve within generations. Considering how long-lived we are, this is a good thing.

        For example my partner spent her early years on a farm with an outhouse, eating food cooked over a wood fired stove. Now she has a doctorate and a highly technical job, and speaks a different language. Try doing that type of switch with, say, a dog or an ant. How many generations would such changes take?

  4. October 20, 2011 9:06 pm

    Even DNA can have its evolution sped up–Look at DNA viruses, like me. I evolved from cells. Smallpox and Herpes probably did too. So what if we don’t have any more ribosomes. You call it DEGENERATIVE evolution.

    Degenerative evolution happens to humans, too; much of your body parts (jaw, muscles, immune system) are degenerate compared to those of your fellow apes.

    • October 21, 2011 11:56 am

      No they’re not. I’ve got fire, so I don’t need to have those huge jaw muscles. That’s why my fellow apes are hiding in the forests, while my fellow humans are cutting them down.

  5. October 20, 2011 10:52 pm

    Hmm… thinking about this, try Tiptree’s “Your Haploid Heart” for a humanoid species that has a different sort of genetic adaptiveness.

  6. October 21, 2011 1:22 pm

    A human without culture (as he defined it) is non-functional.
    Yes. This is dangerous territory but, it turns out that forms of “natural selection” act on culture too, the evolution of memes. Even languages evolve along the same math that DNA does.

    And inbetween DNA and memes there is epigenetics–if you starve, your unborn children will have more efficient metabolism (and weigh too much) because their DNA gets imprinted (methylated) differently. Very dangerous to think about this stuff because it sounds like Lysenko though it’s not.

    • October 21, 2011 2:41 pm

      The irony is that it’s what we’re doing here. We’re using something like html, which is hypertext markup language. Epigenetics are simply a way of marking up a genome.

      I think the most useful thing about the concept cultural evolution isn’t necessarily memes, it’s the idea that cultural change is path dependent. This shows up in all sorts of ways right now (I’m thinking primarily about politics). In theory, every political problem the US faces right now is readily solvable, but somehow, we can’t bring ourselves to do it. I suspect that this is path dependence, where the way our political culture has changed in the last 30 years has made it uniquely hard to deal with a particular set of otherwise solvable problems. I should point out that I got this idea from David Sloan Wilson (SUNY Bringhamton).

      Cultural evolution is also useful, because we can also talk about cultural diversity as something that matters. Different groups of people do better under different circumstances, and attempting to make everyone the same poses the usual problems.

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