Everything Dies, Right? But Does Everything Have To Die? Here’s A Surprise

Oct 2, 2014

Image credit: University of Wisconsin- La Crosse

By Robert Krulwich and Adam Cole

A puzzlement.

Why, I wonder, are both these things true? There is an animal, a wee little thing, the size of a poppy seed, that lives in lakes and rivers and eats whatever flows through it; it’s called a gastrotrich. It has an extremely short life.

Hello, Goodbye, I’m Dead

It hatches. Three days later, it’s all grown up, with a fully adult body “complete with a mouth, a gut, sensory organs and a brain,” says science writer Carl Zimmer. In 72 hours it’s ready to make babies, and as soon as it does, it begins to shrivel, crumple … and usually within a week, it’s gone. Dead of old age.

Sad, no? A seven-day life. But now comes the weird part. There’s another very small animal (a little bigger than a gastrotrich) that also lives in freshwater ponds and lakes, also matures very quickly, also reproduces within three or four days. But, oh, my God, this one has atotally different life span (and when I say totally, I mean it’s radically, wildly, unfathomably different) from a gastrotrich.


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13 comments on “Everything Dies, Right? But Does Everything Have To Die? Here’s A Surprise

  • 2
    Aber ration says:

    “Why the hydra? If nonsenescence, or biological immortality, is an option in nature, how come this particular mini-bit of pond scum got the big prize? Why not the gastrotrich? Why not (excuse me for asking) … us? ”

    This question reminded me of “The Hitchhikers Guide to the Universe”. We discover eventually that really the world was created by white mice and we are just part of an experiment.

    Turned out god created the Hydra in his own image and then just filled up the planet with other inferior stuff like us.



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  • 3
    inquisador says:

    So what that the hydra constantly renews it’s cells; we do that too, so what’s the difference? It can’t just be that ours are more specialized, as that doesn’t stop the renewal process.

    There must be more to it?



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  • My fat cells get replace on average every 8 years, many other bits get replaced faster, heart cells slower. The issue for long life is the accuracy of the replacement and this depends on copying my chromosome idefinitely without error. Telomeres are little buffers at the end of chromosomes that tell the copying process when to stop. They deteriorate (are worn down) with the copying process sadly and when gone copying mistakes accrue. My wild eyebrows, forgetful of the original neat plan, signal this “replicative senescence” and the increasing chance of miscopying a heart cell or two…. The criticallity of these latter in the complex mechanics of this machine may indicate an optimisation of copying for heart cells between ready repair through frequent copying/replacement and early wearing out the copy telomeres.



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  • 6
    inquisador says:

    …without error…!

    Hmmm,

    So the telomeres themselves (my spell-check suggests omelettes for those) are the one things in the body that are not renewable with precision, which causes senescence to creep in?

    I suspect I am missing something. I don’t wish to impose the task of rectifying my missing education on you, Phil, that would not be fair. So hi ho hi ho, it’s off to wiki I go.



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  • In embryonic stem cells, telomerase is activated and maintains
    telomere length and cellular immortality; however, the level of
    telomerase activity is low or absent in the majority of stem cells
    regardless of their proliferative capacity. Thus, even in stem cells,
    except for embryonal stem cells and cancer stem cells, telomere
    shortening occurs during replicative ageing, possibly at a slower rate
    than that in normal somatic cells.

    http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2360127/

    The Hydra cells only ever reach embryonic stage

    Additionally, under defined conditions, embryonic stem cells are
    capable of propagating themselves indefinitely

    http://en.wikipedia.org/wiki/Embryonic_stem_cell

    Is that the reason why they don’t fit into the graph on the video, because they don’t actually have babies and are just trapped in a loop?

    Am I wrong to suggest that the evolutionary process is in us in that we produce embryos and we DO live forever through our offspring???



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  • Yes. I can’t remember which book it was, “The God Delusion” I think, that RD asks why it is that sexual reproduction is the choice of large animals and very few animals reproduce asexually(although the Hyra reproduce by budding) and what advantage sexual reproduction has in evolution. I think this might be the answer in that two animals coming together and producing a third with slight variation in genes will have a pyramid effect and therefore accellerate evolution immensely. It might also explain why some lizards, such as Komodo Dragons, have evolved very little and the Hydra not at all for 13 million years, if I have read it right. In my mind the sexual antics of the Bonobo ape, our closest ancestor, might be the reason for accelerated evolution and why other apes, that have patriarchal and therefore single male genes for long periods, are lagging behind. Also, the ageing process, as in the link above, is another vital part to accelerate evolution and a later addition to the Hydra gene. Thats where my free thinking has gone so far anyway??



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  • Which could also explain why DIT is also true because monogamy and, in humans, marriage is a way that one set of genes are not the start of many pyramids and evolution is at its fastest, although this is not always the case as in Genghis Khan



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  • I assert humans are immortal too, if you look at them the right way.

    Humans are a bit like asymmetric amoebas. They split off some cells. We call these cells sperms and eggs. These continue to live for a while with a separate existence from the original host.

    Sometimes these sperms and eggs get together (I am also thinking in terms of the gamut of plant and animals, not just humans). When they join you might ask “what is the age of the union?”

    The Christian tradition is to restart the clock at 0, but those two cells can be traced back generation after generation of cell splitting of spermatocytes and oocytes in their respective hosts. You can even chase them back in an unbroken chain of life through the egg and sperm cells that created that host.

    There is no spontaneous creation of life anywhere in the reproductive process, just budding off of life from existing and ancient life. The creation of life is more like putting on weight than some spark of lightning.

    You can chase this process back presumably to a single life form that has died a trillion deaths, but still lives on in other species, evolving into the tree of life.

    Genetically, life is just one big life, that morphed into various forms and that lives in a variety of separate water sacs.

    Metaphysicians often claim that all life is literally you staring back at you. It is also true scientifically if you look at the ordinary facts of reproduction is in a slightly different way.



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  • Hydra is only a dead end to the extent that we can reliably predict the future. Seeing as it’s still alive now and that every cell in every living organism currently alive has never yet died and that they all originated by splitting from existing cells then you could claim that every living cell is effectively 3.5 billion years old. With a few cumulative modifications along the way.

    Kind of like an extensively modified car that has acquired a new exhaust, alternative fuel, new engine, new wheels, new interior fit out, new body, new suspension, re-wired electrics, new windows, doors replaced, and better seats. Without ever being off the road. But it’s still the same car.

    If you could establish the Hydra on a suitable exoplanet with the right environment and food sources you might find it is no longer an evolutionary dead end. There’s a theory that this has already happened.



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