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That's very true but even if these forces catch 99% of significant mutations then you'd still see an increase in pregnancies resulting from that remaining signi

That's very true but even if these forces catch 99% of significant mutations then you'd still see an increase in pregnancies resulting from that remaining significant mutations over baseline. But more importantly, our genomes have a lot of "junk DNA" where a mutation will not affect anything at all and almost everyone has these. From the article it looks like these were the mutations the researchers were looking at.

refurb 6y ago
“Junk DNA” as a concept is pretty dated. It used to refer to non-protein encoding regions of DNA. In our infinite wisdom we assumed these segments of DNA had no purposes yet it turns out they play an important role in DNA packing and unpacking which directly influences gene expression.
BitwiseFool 6y ago
I remember hearing a hypothesis that "junk DNA" acts as a kind of shielding against mutations. From a probability standpoint, the more non-coding DNA you have, the less likely an error is to hurt the lifeform. Taken to an extreme, if every DNA sequence did something a singe error would cripple the organism.
- syrgian 6y ago
  However, the probability of the DNA getting hit would increase linearly with the amount of junk DNA, wouldn't it? So the chance of good DNA getting hit is exactly the same as without junk. Not sure how it would help shielding the good DNA, unless it acted as a barrier.
  - selectodude 6y ago
    Mutations from radiation come from particles literally slamming into the DNA and screwing it up. The more spaced out the important parts are, the lower the probability that the particle hits a piece of DNA that’s important.
    - HPsquared 6y ago
      If I place 4 cups of water out in the rain, does their spacing affect how much water lands in each cup?
      - afiori 6y ago
        It depends on how you place them, horizontaly on a table no, in a pyramid yes.
      - BitwiseFool 6y ago
        I see what you're getting at, but in this example there would be millions of cups and the individual raindrops would be spread out over a massive area of land.
        jakear 6y ago
        That doesn’t change anything. The probability an important cup gets hit is always equal to the surface integral of the rain’s flux across the important cup openings. Whether there are unimportant cups nearby doesn’t change anything.
- ruined 6y ago
  that makes intuitive sense but at least in the case of ionizing radiation it's a little like making a target circle bigger to protect the bullseye which remains the same size. there's still the same chance of hitting the bullseye, no matter how you change the chance of not missing the paper.
  - jxy 6y ago
    Think of it as a 3D sphere instead. You would get a shielding effect.
    - cma 6y ago
      There is already one milligram of atmosphere over the cross sectional area of a cell nucleus, so it doesn't seem like it could change much for cosmic rays. All DNA in a human cell is about 6 picograms. That's 166 million times more mass of atmosphere. The elements may be less effective etc. but it still seems like any junk dna shielding would be negligible. Maybe cosmic rays aren't the main source of ionizing radiation throughout the evolutionary period though.
    - davrosthedalek 6y ago
      If the cell around is not shielding it, the little bit of extra DNA is not shielding it either. You need a lot more atoms to get a shielding effect.
- jacquesm 6y ago
  I reject the term 'junk dna'. Until we understood the basics of DNA all of it was 'junk', then bit by bit we are making headway into understanding some of it. If we're ever done I predict there will be no junk DNA left. Nature is much too efficient to spend that much energy on something that it ends up not using.
  - david-gpu 6y ago
    > Nature is much too efficient to spend that much energy on something that it ends up not using. And yet nature somehow finds it acceptable to grow a nerve all the way from a giraffe's head down its neck, loop around its heart and then go all the way back up through its neck until reaching the head. [0] [0] https://rationalwiki.org/wiki/Laryngeal_nerve https://rationalwiki.org/wiki/Laryngeal_nerve
    - jacquesm 6y ago
      Yes, and there are a number of other examples like that. But that doesn't detract from the general case in the least: if energy can be saved then it usually will be saved, especially if a mechanism lasts for a long time. The idea that the base mechanism of encoding life patterns is going to be on the order of 70% or more 'junk' requires a very good explanation. Why the argument presented here is invalid I'll leave for you to figure out.
sesuximo 6y ago
Wouldn’t that depend on the size of the study? Seems like catching an orders of magnitude smaller difference would require orders of magnitude more samples... and the population is only so big..

refurb 6y ago

“Junk DNA” as a concept is pretty dated. It used to refer to non-protein encoding regions of DNA. In our infinite wisdom we assumed these segments of DNA had no purposes yet it turns out they play an important role in DNA packing and unpacking which directly influences gene expression.

BitwiseFool 6y ago

I remember hearing a hypothesis that "junk DNA" acts as a kind of shielding against mutations. From a probability standpoint, the more non-coding DNA you have, the less likely an error is to hurt the lifeform. Taken to an extreme, if every DNA sequence did something a singe error would cripple the organism.

syrgian 6y ago
However, the probability of the DNA getting hit would increase linearly with the amount of junk DNA, wouldn't it? So the chance of good DNA getting hit is exactly the same as without junk. Not sure how it would help shielding the good DNA, unless it acted as a barrier.
- selectodude 6y ago
  Mutations from radiation come from particles literally slamming into the DNA and screwing it up. The more spaced out the important parts are, the lower the probability that the particle hits a piece of DNA that’s important.
  - HPsquared 6y ago
    If I place 4 cups of water out in the rain, does their spacing affect how much water lands in each cup?
    - afiori 6y ago
      It depends on how you place them, horizontaly on a table no, in a pyramid yes.
    - BitwiseFool 6y ago
      I see what you're getting at, but in this example there would be millions of cups and the individual raindrops would be spread out over a massive area of land.
      - jakear 6y ago
        That doesn’t change anything. The probability an important cup gets hit is always equal to the surface integral of the rain’s flux across the important cup openings. Whether there are unimportant cups nearby doesn’t change anything.
ruined 6y ago
that makes intuitive sense but at least in the case of ionizing radiation it's a little like making a target circle bigger to protect the bullseye which remains the same size. there's still the same chance of hitting the bullseye, no matter how you change the chance of not missing the paper.
- jxy 6y ago
  Think of it as a 3D sphere instead. You would get a shielding effect.
  - cma 6y ago
    There is already one milligram of atmosphere over the cross sectional area of a cell nucleus, so it doesn't seem like it could change much for cosmic rays. All DNA in a human cell is about 6 picograms. That's 166 million times more mass of atmosphere. The elements may be less effective etc. but it still seems like any junk dna shielding would be negligible. Maybe cosmic rays aren't the main source of ionizing radiation throughout the evolutionary period though.
  - davrosthedalek 6y ago
    If the cell around is not shielding it, the little bit of extra DNA is not shielding it either. You need a lot more atoms to get a shielding effect.
jacquesm 6y ago
I reject the term 'junk dna'. Until we understood the basics of DNA all of it was 'junk', then bit by bit we are making headway into understanding some of it. If we're ever done I predict there will be no junk DNA left. Nature is much too efficient to spend that much energy on something that it ends up not using.
- david-gpu 6y ago
  > Nature is much too efficient to spend that much energy on something that it ends up not using. And yet nature somehow finds it acceptable to grow a nerve all the way from a giraffe's head down its neck, loop around its heart and then go all the way back up through its neck until reaching the head. [0] [0] https://rationalwiki.org/wiki/Laryngeal_nerve https://rationalwiki.org/wiki/Laryngeal_nerve
  - jacquesm 6y ago
    Yes, and there are a number of other examples like that. But that doesn't detract from the general case in the least: if energy can be saved then it usually will be saved, especially if a mechanism lasts for a long time. The idea that the base mechanism of encoding life patterns is going to be on the order of 70% or more 'junk' requires a very good explanation. Why the argument presented here is invalid I'll leave for you to figure out.

sesuximo 6y ago

Wouldn’t that depend on the size of the study? Seems like catching an orders of magnitude smaller difference would require orders of magnitude more samples... and the population is only so big..