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Science

How Dad's Stresses Get Passed Along To Offspring (scientificamerican.com) 109

An anonymous reader quotes a report from Scientific American: A stressed-out and traumatized father can leave scars in his children. New research suggests this happens because sperm "learn" paternal experiences via a mysterious mode of intercellular communication in which small blebs break off one cell and fuse with another. Carrying proteins, lipids and nucleic acids, these particles ejected from a cell act like a postal system that extends to all parts of the body, releasing little packages known as extracellular vesicles. Their contents seem carefully chosen. "The cargo inside the vesicle determines not just where it came from but where it's going and what it's doing when it gets there," says Tracy Bale, a neurobiologist at the University of Maryland School of Medicine. To probe the inheritance of such changes at the cellular level, Bale and co-workers performed a series of mouse experiments.

In one set of experiments [Jennifer Chan, a former PhD student that was part of the study] stressed a group of male mice, let them mate and looked at stress responses in the pups. The clincher was a set of in vitro fertilization -- like experiments in which she collected sperm from a male mouse that had never experienced induced stress. Half his sperm went into a lab dish with vesicles previously exposed to stress hormones. The other half was cultured with vesicles that had no contact with stress hormones. Chan injected sperm cells from each batch into eggs from a non-stressed female, then implanted the fertilized eggs -- zygotes -- into the same foster mom. The pups from non-stressed zygotes developed normally. Pups from stress-exposed zygotes, however, showed the same abnormal stress response as those whose dads had experienced stress before mating. That showed extracellular vesicles act as the conduit for transmitting paternal stress signals to the offspring, Chan says.

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How Dad's Stresses Get Passed Along To Offspring

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  • I want to meet the person that is not completely messed up by their parents. Isn't this how it works?

    --
    Imagination is more important than knowledge. - Albert Einstein

  • Skeptical (Score:3, Interesting)

    by Aighearach ( 97333 ) on Thursday November 08, 2018 @11:39PM (#57615702)

    It seems like it might just be that adding the vesticles pollutes the petri dish environment in a harmful way.

    I'd like to see this where a control was given different vesticles, instead of only controlling for "added" vs "not added."

    • Re:Skeptical (Score:4, Informative)

      by Xenx ( 2211586 ) on Friday November 09, 2018 @12:25AM (#57615806)
      The summary specifically mentioned that both groups had vesicles added. One group had stress hormones in the vesicles, one group didn't.
      • Use quotes. Which words in the summary do you believe say that?

        • by Xenx ( 2211586 )

          Half his sperm went into a lab dish with vesicles previously exposed to stress hormones. The other half was cultured with vesicles that had no contact with stress hormones.

          • Good job, you finally said something!

            I did mention 3 groups I'd want to see in the study, and you're right; I mis-identified the missing one.

            But my complaint is still largely the same.

            Another complaint I have; this study only used the sperm of one mouse.

            The actual interesting part of the story isn't the mice though, it is the follow-up experiments they did using humans. Multiple humans, even. If the mice were the interesting part, they'd have redone it at a normal scale instead of switching to humans.

            • by Xenx ( 2211586 )

              Good job, you finally said something!

              There is no finally anything. I said something the first time. Your choice of response makes you sound like a condescending twat that cannot take criticism.

              I did mention 3 groups I'd want to see in the study, and you're right; I mis-identified the missing one.

              You only mentioned wanting them to test with different vesicles. There was no mention of three groups. You then proceeded to mention they only controlled with vesicle and without vesicle. I merely corrected your interpretation. I don't know what you'd want to add to a third vesicle that would provide a known response in the test subject, as the third con

    • It seems like it might just be that adding the vesticles pollutes the petri dish environment in a harmful way.

      I'd like to see this where a control was given different vesticles, instead of only controlling for "added" vs "not added."

      Epigenetic changes have been known for awhile, this study isn't new in that regard, just another nail. It is a neat experiment though.

      • by HiThere ( 15173 )

        This is a different mechanism than epigenetic modifications of DNA (e.g. methylation of various codon sites). I'm not sure it counts as epigenetic modification at all.

        • Are you aware "methylation at codon sites" doesn't even make sense? Epigenetics is the switching on and off of genes in a hereditary or environmental manner not directly relating to evolutionary mutation (aside from the fact the genes evolves in the past but were deactivated by default.)
          • by HiThere ( 15173 )

            It may not make sense to you, but that's the way it happens. Methylation of a portion of the backbone holding the codon keeps the histamines from unwrapping the code so that it can be used. These are supposed to be stripped off during meiosis, but IIRC the process doesn't always happen, which is how you get inherited epigenetic phenomena. Normally it's the process used to tell, say, a liver cell that it's not a bone marrow cell.

            This process sounds more analogous to the way that mitochondria are carried i

            • Epigenetics is a lot bigger than a singular effect.
              • by HiThere ( 15173 )

                Yes, but the name applies to, or at least used to apply to, molecules or radicals that attach to the DNA to modify its expression. Methylation is the one I'm least unfamiliar with. It didn't apply to stuff carried along on the cell wall or in the cytoplasm.

                • I didn't suggest there was anything involved outside of the nucleus, but there are a huge number of mechanisms that we know of, seemingly growing every couple years, which extend well beyond a singular trigger. It has a lot more to do with how operons are utilized that it does anything else.
    • by Anonymous Coward

      The most significant stressor in life is the force of Government over you, like master to a slave.
      You are their slaves.
      A slave indeed.
      Remove that and you'll really begin feeling free again.

      • My advice, move to a place without a powerless, failed government for six months and compare.

  • This isn't what I meant when I said we need to be taking a more careful look at how parents' stresses impact their children's development.

  • Lamarck's revenge (Score:5, Interesting)

    by blindseer ( 891256 ) <blindseer@@@earthlink...net> on Friday November 09, 2018 @01:27AM (#57615938)

    Everything old is new again. Lamarck had his theory of evolution and Darwin had his, and for the longest time Darwin was thought to have cracked the code. I guess just like how Newton figured out physics on the macro scale there's more to be seen when one looks closely enough to see where the theory doesn't explain it all.

    I recall seeing an interesting TED Talk from a man explaining how homosexuality was not genetic but epi-genetic. That is "epi-" meaning "above" or "beyond". Epi-genetics means that environmental factors placed upon the parents produce something very much like genetics on the child, as in inherent to their "code" or "being", that cannot be undone after the child is conceived. In this TED Talk the man used his son as an example of this in that the stress he and his wife had in their life produced a homosexual son because in prior times, and through many iterations of evolution taking place, there is a survival benefit of the clan or species in having homosexual men in times of stress. Things like war and famine might be where a "pause" in further offspring would be beneficial.

    This fine article performed the experiment on mice and seemed a bit vague on the behavior they observed. If experiments like this can tell us more on human behaviors then there could be a lot on how we could improve society for the future. Since I already stepped on the landmine that there is a theory, not proven by the way but merely an educated guess by a man that seems convinced of the science, where stressed parents produce homosexual children then I feel like stepping on another will not be any worse.

    There's the theory that a stressor that is thought to lower intelligence and raise tendencies to criminal behavior, that is children conceived out of marriage. Women being pregnant without the biological father around (or other male stand in) is stressed in a way that evidence shows might be epi-genetic. There's other possible reasons for this, like such stress in childhood upon the child will bring an adult that is aggressive and poorly educated and therefore likely to exhibit anti-social (or just plain criminal) behaviors. Or that women in such a situation will not have the time for breastfeeding (shown to be far healthier than formula), time for bedtime stories (shown to improve education later), or time for making a proper meal with any regularity. Children raised in a low stress environment tend to become well behaved adults.

    Will reduced stress in society mean no more gays and criminals? Well, that would be an interesting theory to test. I don't know how we'd do that without getting into telling parents how to raise their children. Epi-genetics or not there's plenty of evidence on how a downward spiral in society can be broken by one generation of children raised in a healthy family structure. Lamarck may not have got it all right, but he wasn't all wrong either.

    • It sounds like you are projecting some personal test onto other people. It is hard to take you seriously when you combine these arguments as both can be subjective.

      If your argument is that there is some fictional place where everyone will just get along and everyone will be at the same "place" in society, then you need look no further then communism.

      --
      “If it doesn’t fit, you must acquit.” - Johnnie Cochran

      • Re:Lamarck's revenge (Score:5, Interesting)

        by blindseer ( 891256 ) <blindseer@@@earthlink...net> on Friday November 09, 2018 @03:42AM (#57616122)

        It sounds like you are projecting some personal test onto other people.

        It sounds like you are trying to read my mind and psychoanalyze me base on a few paragraphs.

        It is hard to take you seriously when you combine these arguments as both can be subjective.

        Then don't take me seriously. I'm merely pondering on where epi-genetic research might lead us.

        If your argument is that there is some fictional place where everyone will just get along and everyone will be at the same "place" in society, then you need look no further then communism.

        That's not my argument. My argument is that if stresses on the parents means poorly behaved children then it would be to our benefit to reduce stresses on parents.

        I've been watching some interesting videos lately on how IQ correlates to financial and other success in life, as well as what factors contribute to IQ. The most recent video I saw was on "McNamara's Folly" or Project 100,000, by someone that wrote a book on this and who's name I don't recall right now. I don't have the link to the video as I found it on a different computer than I'm using right now but here's the Wikipedia page on that project:
        https://en.wikipedia.org/wiki/... [wikipedia.org]

        Other videos I've seen were from Dr. Jordan Peterson where he describes how the US military has a large database of how people scored on their version of an IQ test and how well the people performed in their job. Dr. Peterson and others I've seen describe various possible contributing factors to IQ, and therefore future success. This simply fascinates me. There's some dispute on how genetics influence IQ, but no dispute that IQ is influenced by genetics. Maybe genetics contributes 80% to IQ, maybe only 50%. So, what contributes the rest? Can this be explained by epi-genetics? If so, then how much? Then comes the question of real importance, if epi-genetics influence future success then what should we do with this information?

        I don't want everyone in the same place since that means, as you point out, communism where everyone has an equal share of the misery. I want people to reach their greatest potential. If stresses on the parents means lowered chances of success for the children then we, as a society/nation/species/community, should do what we can to lower this stress. If epi-genetics means nothing then we should still be excellent to each other but know that such efforts may not be rewarded in better behaved children. That is we'd be no better rewarded than we already know with things like well fed children leading to healthy adults, as opposed to malnourished children leading to adults being stunted in physical and mental development.

        I mentioned the TED Talk on a possible link of epi-genetics to homosexuality as something this article reminded me about and shows possible effects on humans. Homosexual tendencies are "bad" in that the species cannot propagate with these tendencies. If homosexual behavior is genetic then one could assume that it is unlikely to have survived to today. This then leads one to think about how it might propagate, since a genetic trait that's counter to propagating the species should fade in time. There must be something beneficial to this, and there must be a mechanism for it to exist in following generations. This is perhaps no different than anti-social behavior (or rather what we define today as such) being beneficial to the species. There's little doubt that stressed parents lead to aggressive children, what might be left unexplained is the mechanism behind it. A stressed parent might need aggressive children since war is a stressor and aggressive people tend to be more successful in war. There's now another layer to the nature vs. nurture debate and it's called epi-genetics.

        • It could still be genetic, the add on effects can effect group selection in a cooperative species like ours. Even if we weren't social, you'd still see, say, male infertility due to genetic causes, if the same genes caused hyperfertility in females. It's just the "birth order" trends that would necessarily be epigenetic.
        • I read in one of Matt Ridley's books that there was a positive correlation between the number of male children a woman had and the chance of homosexuality in the next male child. i.e. more older brothers, more likely to be gay. Probably "Nature via Nurture" since that one was about epigenetics.
      • If your argument is that there is some fictional place where everyone will just get along and everyone will be at the same "place" in society, then you need look no further then communism.

        If people just 'got along' and everyone were 'at the same place' under Communism, then why did it require such a blisteringly high level of coercion?

        • by tsqr ( 808554 )

          If your argument is that there is some fictional place where everyone will just get along and everyone will be at the same "place" in society, then you need look no further then communism.

          If people just 'got along' and everyone were 'at the same place' under Communism, then why did it require such a blisteringly high level of coercion?

          Brace yourself for some great examples of the "no true Scotsman" fallacy.

    • by The Evil Atheist ( 2484676 ) on Friday November 09, 2018 @04:54AM (#57616224)
      Lamarck is wrong and epigenetic does not salvage Lamarck in any way. What Darwin's Theory is not about is where sources of variation come from, but how they persist. Epigenetic traits do not last more than a few generations and cannot contribute to speciation. It is still the genes that are selected on.

      The rest of what you write is just dribble. Part obvious - raise children well, who would have thought - and part nonsense, "therefore epi-genetics and evolution".
      • by Whibla ( 210729 )

        Epigenetic traits do not last more than a few generations and cannot contribute to speciation. It is still the genes that are selected on.

        That is a very bold claim, given that epigenetic factors can alter or suppress gene expression and those genes might affect other genes and, hence, potentially all the cellular production machinery.

        Other than your 'feelings' on the matter do you have any evidence for your claim - and please remember that a lack of evidence is not evidence of a lack (of a potential mechanism)...

        • Re: (Score:3, Interesting)

          Suppressing gene expression has no affect on whether genes get inherited and selected for or against. The epigenetic effect does not come from the gene itself - it is not it's phenotype. So another organism with the exact same gene, but without the epigenetic effect can pass along that gene to an organism where its phenotype can be expressed and contribute (or be detrimental) to its survival.

          For an epigenetic effect to suppress gene expression to the point that it kicks the gene out of the gene pool, the
          • Suppressing gene expression has no affect on whether genes get inherited and selected for or against.

            Doesn't it? Behavioral changes (for whatever reason) can affect which genes are later inherited. This is what allows a species to adapt to a changing environment.

            • To clarify, this was meant in the context of choosing mates, not that behavior would physically affect gene inheritance.
          • by Whibla ( 210729 )

            That was an awful lot of words to say nothing about whether or not epigenetics can cause speciation - which was the point I raised. And, again, you provide no evidence just your belief stated as fact.

            The epigenetic effect does not come from the gene itself

            No, indeed, epigenetic changes arise as a result of hormones (coded for by genes), non-coding RNA (produced from a DNA template), DNA methylation (caused by enzymes (DNMTs) within the cells), and probably other factors we have yet to discover. The fact they don't, necessarily, come from the gene they're modifyi

        • Hmm... but if there are just population level epigenetic changes, you'll end up with something more like a ring-species than a non ambiguous speciation event, yes?
          • by Whibla ( 210729 )

            I'm pretty sure that there's several different ways for speciation to occur, but I'm equally sure I'm not really sure of all the details. The point of my original post was simply to question an assertion based on what I saw as false certitude.

            As a prelude I'll just say that, by my understanding, findings over the last few decades have made the term 'species' rather vague, as we've discovered that individuals from different species can in fact interbreed, with the offspring being fertile (unlike for example

    • Re: (Score:2, Insightful)

      by spaceman375 ( 780812 )

      You make it sound as if this is the full explanation for how homosexuality occurs. It's far more complicated than that. For instance, with each subsequent son a woman gives birth to, the likelihood of that son being gay goes up. To the point that a 14th son has a 50% chance of being gay. That's postulated to be the mother's immune system learning to clear out androgens and the cells that produce them.
      Another confounding factor is that women who have 2 or more gay brothers have more offspring than women with

      • by MobyDisk ( 75490 )

        Implied in your post is the thought that homosexuality is an undesirable condition that would go away if "things were perfect".

        Nothing in blindseer's post implies any such thing. You just made-up a bunch of stuff, attributed it to him, then attacked it. [wikipedia.org] You even put stuff in quotes, as if they were in the post! Probably someone else said those things to you, and you are transferring.

  • I wasn't stress out until AFTER the children were born.

    gosh - raising children is stressful. Making them is easy.

  • by Anonymous Coward

    The fathers have eaten sour grapes and their children's teeth are set on edge.

  • "Insanity is hereditary; you get it from your kids."

    mnem
    This is where I usually put some pithy remark.

  • ... for the unstressed control group. Because the primary source of male stress is having to deal with the female of the species.

    Now pardon me while I make up my bed in the garage.

  • It sure sounds like a really good way for animals to learn what is deadly and what to avoid. If you run into deer where hunters kill them, they are scared of people. If you see deer in a park where people feed them by hand, they trust people. Do their offspring get some of this response via the mechanisms in the study? I bet they do at least by some degree.

  • We learn from stresses, this could be part of a mechanism for passing information genetically to offspring. Sorry ladies, you won't replace fathers with artificial sperm anytime soon, we pass genetic wisdom to our children.
  • So, all those snowflakes flipping out over the last two elections are going to bleb all over the place?

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