Radio

How trauma is passed down through the generations in our DNA

23 April 2016

9:00 AM

23 April 2016

9:00 AM

Sue Armstrong’s programme on Radio 4 All in the Womb (produced by Ruth Evans) should be required listening for anyone dealing directly with the refugee crisis, with those who have fled from intense fear and terrible violence in their home countries. Armstrong has been investigating recent developments in our understanding of the impact of severe trauma, how it affects not just the mind but also the body, creating physical changes that also need to be addressed. Those who lived through the Holocaust, for example, who were in prison camps or were forced to hide in dark, cramped, inhuman conditions, perpetually afraid that at any moment they might be discovered, have been found to have low levels of cortisol.

This is the hormone that the body releases into the bloodstream as we experience panic and fear and whose main function is to mobilise our energy and will to survive. Much more significant, though, is the discovery that the descendants of those who have suffered war, violence, incessant fear also have lower levels of cortisol than average. The biblical warnings about bad times being passed on from generation to generation are not just mythical prophecies. Scientists now have proof that trauma is passed on, or rather its impact on how we feel, and how we behave, can be superimposed on the DNA of the next generation.

Dr Rachel Yehuda works in New York and had a critical opportunity to investigate the effects of trauma on body and mind after 9/11. We heard from Cathy Langford, who woke up on the morning of 11 September and realised she was going into labour. It was a beautiful day and she and her husband at first thought what a perfect day on which to give birth. But they were living in an apartment within sight of the Twin Towers and as they ate breakfast their building shook and they heard a huge explosion. Looking out from their kitchen window they could see clouds of smoke turning to black, and on the ground the bodies of those who in desperation had jumped out of the building. How could she give birth now?

Two hundred women were in labour on or around that day in the city and they have been found, and their babies, to have low levels of cortisol. Yehuda says these discoveries should alert us to the importance of how we react and respond to trauma survivors. Their prospects for recovery, she argues, are dependent on what happens to them immediately after the trauma. We need to provide ‘a healing culture’. Did someone believe them? Did someone understand what they have gone through? Did someone welcome them?


On the World Service, Catherine Carr’s clever interview series Where Are You Going? (produced by Jo Coombs) has returned for a special season taking us globetrotting to Amsterdam, New York and this week to Kolkata in India. All she does is take her recorder on to the street to ask passers-by where they are going. It’s such a simple idea but, perhaps surprisingly, among the mundane off-to-the-hairdresser or to-meet-a-friend responses Carr often stumbles upon real stories that come across even more powerfully because they’re so unexpected, so random and unplanned.

We heard this time from a woman buying sarees, a young man on his way home from cricket practice (‘I think of myself as a great batsman’), a student on her way to her classroom at the university. What is she studying? Butterfly ecology. Why? ‘It’s not just about the beauty. They are an indicator species…They are also very sensitive.’

Carr meets a lot of strong women, keen to assert their independence, especially from the idea of ‘romantic’ love. Take the student who was on her way to the university library to read Macbeth. ‘Everyone in India talks about Shakespeare as an elite genre of literature,’ she says. But ‘he’s actually right there making big jokes in his plays’. Describe yourself, says Carr. ‘I have very strong opinions,’ she says. ‘I’m a feminist to the core.’ And you totally believe her because of the power in her voice, her vivacity and authority. ‘I grew up in a family where gender roles weren’t so important. In my house it was my Dad who packed lunch and made food very often.’

Another student is on her way to buy books for her course in banking. She’s ambitious to get a good job. ‘It’s very necessary for women because their rights are not safe.’ After marriage, they change. She sounded anxious, but at the same time driven to achieve. You knew she would make it.

Downtown Carr meets a lawyer working for the railway tribunal. ‘Possibly not the most fun job in the world but someone’s got to do it.’ What’s the worst bit of the job? Carr asks. ‘Death,’ he replies. ‘Horrible, horrible death. Lots of multiple limbs. You have to try to maintain the railway’s stance on that.’

The next person who answers Carr’s question happens to be a young man with a limp. ‘What’s happened to your leg?’ It was cut in half in an accident on the railway, he tells her. ‘Is your leg metal or plastic?’ Plastic, he replies. He’s only 19.

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Show comments
  • enoch arden

    If this finding is true, it marks the end of Darwin’s “natural selection” model of evolution. For good. Finally, we have experimental evidence refuting this ridiculous 19th century superstition that the progress occurs through “survival of the fittest” as it was popularly explained by Spencer (the fittest are those who survive). What are we going to do with the school textbooks full of this rubbish?

    • Jeffrey Vernon

      It is not being claimed here that the mother’s DNA was altered in the egg cells by the trauma, and THEN that this alteration was transmitted to the offspring – the women were already pregnant at the time of 9/11. Decreased levels of cortisol might come about if you were raised in a stressful home. If you think Darwin is hard to take, Lamarck is no easier.

      • enoch arden

        There were observations reported that an experience acquired by mail rats was inherited by the next generations. There are also observations of the correlation between the rate of mutations and the environmental conditions. Conclusion: mutations are not random.

        • Jeffrey Vernon

          I see the difficulty. What the rats ‘inherited’ was not a mutation. There have been reports that fear experienced by mice can be ‘inherited’ by the pups. The mechanism is not known, but it does not appear to be mutation (we can screen all the genes in the offspring to check for new mutations). The theory is that some genes in the mice become methylated, perhaps after a stressful experience, which tends to switch genes ‘off’, or tune them down, at least temporarily . This methylation is a chemical modification that can be reversed – it does not actually alter the sequence of the gene.

          By the way, natural selection does not depend on mutations being random – it has been known for a long time that some parts of the genome are ‘hot spots’ for mutation, and are more likely to vary. The point is only that these mutations are *spontaneous* – they are not induced by experience (and it is not clear how an experience could mutate a gene in the sperm or the egg cells, except for ‘accidents’ like nuclear exposure). The second point about mutation is that it is continuous throughout the population – there are hundreds of variants of some genes, and if some variants allow the organism to leave even one more offspring than another member of the species, then those genes will become more frequent in the population. There is really no mystique or ‘special pleading’ about it.

          • enoch arden

            1. There is nothing that the fathers convey to their children besides chromosomes. Therefore, any information they acquired that is inherited by their children is encrypted in the chromosomes. The atomic-level mechanism of encryption is unimportant.

            2. Mutations could be either correlated with the external conditions, or uncorrelated. If the former is true, a mechanism of correlation must exist that would be the driving force of the evolution of species. Darwinism assumed that the latter is true and the evolution is driven by selecting “favourable” mutations from the random ones, which is done by killing those who carry these unfavourable mutations as a result of competition. The problem with Darwin’s model is that it cannot be true because it contradicts the principles of thermodynamics.

          • Jeffrey Vernon

            The evidence in the paper points to a methylation mechanism – they found that one of the olfactory receptor genes was under-methylated in the offspring. This is the usual explanation for trans-generational effects, but what is hard to explain (at first) is how the methylation persisted, since it is thought to be ‘wiped’ at the beginning of sperm development (this is necessary because the sperm might give rise to either male or female offspring). I notice in the paper they collected sperm from the fear conditioned mice only 10 days later; almost certainly, these are not new sperm, since the cycle of sperm development takes about 26 days in the mouse. The sperm used to produce the offspring by IVF will have been methylated at the time of the fear conditioning. It is unclear whether subsequent sperm , produced de novo, would have carried the same methylation. Problem: if you look at the sequence of the Olfr151 gene (I’ve just done this) there are NO methylation sites. It is hard to see how the authors could find that this gene was methylated differently between the conditioned and unconditioned mice.

            Your account of Darwin(ism) would not be accepted by any Darwinist I know. Nat selection does not depend on unfavorable genes killing their host, or competitors in the same species ‘turning on’ members with the wrong genes. It is purely a matter of differential reproductive success. Note, Darwin knew nothing about genes. Thermodynamics is neither here or there – the living world is not a closed system, which is what is presumed by the 2nd law of thermodynamics. Energy is always entering and leaving.

          • enoch arden

            I don’t think this biochemical abracadabra is of interest considering the central fact: any information about father’s experience can only be conveyed to the following generations by a genetic mechanism.

            The idea that a steady evolution can be produced by a blind selection mechanism is called Maxwell’s Demon: it cannot be. It isn’t the second law, it is 0 law. In a simple popular form this can be expressed as follows: the complexity of a result of a selection procedure cannot exceed the complexity of the selecting algorithm.

          • Jeffrey Vernon

            The abracadabra matters if the story does not add up. The authors say that the olfactory receptor gene got methylated; their result cannot be right, as there are no methylation sites. The sperm were already mature at the time of the ‘shock’, so we need to know how a sensory experience gets transferred to mature sperm; and whether the memory trace can affect new sperm when they are subsequently manufactured. Unless we ask these questions, the result cannot be replicated independently, and the interesting question of epigenetic inheritance will not advance. There has been a single report in flies, and one in mice; this is really not much to go on – one swallow does not make a summer.

          • enoch arden

            Is there any way to convey information from the father to the children except through his genes?

          • Jeffrey Vernon

            Personally, I think the Dias & Ressler data are fluky: the best result in their paper was the response of the first generation of mice to ONE of the odours, with a P value of 0.003. The other claims, about methylation and the growth of olfactory bulbs, are far less robust, as well as the data about the third generation. My hypothesis is that the odorant acetophenone travelled in the blood and permeated the mature sperm in the epididymis. Odorants, like pheromones, are powerful substances – they can alter the behaviour of female mice in feeding and grooming, for example. The fathers received 5 days of training with odorant and shock – plenty of time for the odorant to migrate to other tissues.

          • enoch arden

            Is you answer yes?

          • Jeffrey Vernon

            It must be. We know that diabetes and schizophrenia run in families, but there is no (known) explanation at the level of genetic mutation. There are bacterial symbionts of sperm, as well as prions. Sperm also contain other cytoplasmic components like protamines and micro-RNAs and mitochondria and immune modulators. Male behaviour towards the mother before mating, and during pregnancy, and after birth of litters affects the phenotype of the young. One whiff of a male can alter the female’s subsequent lactation and grooming behaviour. All of the ‘favourable’ commentary on Dias and Ressler assumes that the mechanism is non-genetic, not that the DNA is modified.

          • Jeffrey Vernon

            As for Maxwell’s Demon; this assumes that a demon ‘opens the door’ between two chambers, so that initially random molecules could be sorted by their different energy levels, violating entropy (so long as the demon did not need any energy, of course). But natural selection does not need to open any doors – the process is not *kinetically* random in the way that gas molecules are. It is random only in the *statistical* sense that most of the genome can undergo mutations. Thousands of breaks in the DNA occur every day in every cell, and most are repaired. But some are not, and we all carry about 100 new mutations that were not present in our parents. This variation between individuals is the substrate of selection – most of it is neutral, but the variants that occur in the protein coding regions can be harmful or beneficial to reproductive success. Here’s a slight change in a pigment molecule that makes me better at collecting fruit in dim light – I collect more fruit and my children grown up faster.

          • enoch arden

            Maxwell’s Demon is a device that selects the needed fluctuations in a system thereby moving it out of equilibrium.

            Let me explain it again. Assume a random number mechanism producing a sequence of letters, and an algorithm that selects sections of this sequence that are interesting as literary pieces. In order to produce a Shakespeare-level literature the selecting algorithm must exceed Shakespeare in its literary talent.

            That is, in order to produce by selection a human being the complexity of the selecting device must significantly exceed the complexity of a human. Shall we assume a superhuman mind for that role?

          • Jeffrey Vernon

            I know what MD is and what problem it is supposed to address. Maxwell wanted to sort the randomly moving molecules so that he could pile up the high energy ones over here, and the low energy ones over there; now the system could do work where formerly there was only random motion. But that is not a problem that natural selection needs to solve. ATP inside cells is not at equilibrium concentrations – there is always far more of it than its precursor ADP. This is because the enzymes that consume ATP are down-regulated when its concentration falls. Secondly, complexity need not arise at the expense of energy at all. A DNA sequence can mutate because of oxidising free radicals in the cell – now you’ve got an altered gene, one which perhaps allows a wider ‘window’ for signal summation after a nerve impulse arrives. None of this required energy inputs.

            Your argument that humans are impossible can equally be applied to plant growth from a seed or embryo development. But these do not violate any law of entropy either, purely because the system is *not closed* which is the assumption of all the entropy arguments. Equilibrium never arises in living cells.

          • enoch arden

            OK. I think you have some problems with basic physics. Start with the school textbook. Try to understand what is entropy. Good luck.

          • Jeffrey Vernon

            I am wondering if you are the same poster who gave me exactly this response before on another discussion thread – or whether there is a tribe of anti-darwinians who use this as a standard brush-off. Since it must be obvious that I know full well what entropy is, and that I probably even resort to the concept in my day job, I can only assume that you have come to the end of your argument.

          • enoch arden

            Sorry if this upsets you. But I can see no point in your discussing the informational aspects of thermodynamics which are clearly beyond your comprehension. Try to do some reading:
            http://plato.stanford.edu/entries/information-entropy/

      • Mary Ann

        Darwin is simple common sense, the antelope with the longest legs is less likely to be caught by the lion unless it’s legs are so long they will break, the antelope with the optimal leg length will be the one that passes on its genes. The idea I find interesting is the size of a human baby’s head, for millions of generations the size of a baby’s head has been governed by the size of a woman’s pelvis, with Casearian sections becoming common will babies heads start to get bigger as those will oversized heads and their mothers no longer die. Will we get to a point when baby’s heads are so big women cannot give birth naturally.

    • Mary Ann

      Why not go back to teaching creationism, that’s silly enough.

      • enoch arden

        Could you please explain your terminology: what exactly do you mean by creationism? Do you agree with Dawkins?

        https://www.youtube.com/watch?v=BoncJBrrdQ8

        • Mary Ann

          Adam and Eve also anything similar in other religions, also evolution with divine intervention.

          • enoch arden

            The Roman Catholic concept of “divine intervention” is undeniably pagan.

            So, what is “creationism” which you suggest to teach?

    • William Haworth

      Not at all. The people who survived the trauma (e.g. the ones who hid during the Holocaust) had low levels of cortisol. The people who were hiding, but had high levels of cortisol, probably whimpered or cried or just plain breathed too loudly, and got caught. The Nazis with guns changed the environment so that low cortisol was an evolutionary benefit, and these people were therefore most fitted to the new environment.

  • James Chilton

    Even if this story is true, low levels of cortisol are not necessarily a bad thing. Chronic high levels of cortisol, which is a hormone released by stress and fear, is a risk factor in mental illness, heart disease, and lower life expectancy.

    Providing a “healing culture” for babies who are “trauma survivors” is pure psycho-babble.

    • Jeffrey Vernon

      What Rachel Yehuda should have done is this: recruit women who had been traumatised, but not pregnant at the time of trauma; wait for them to become pregnant subsequently; check if the offspring were traumatised; check if this was associated with changes in cortisol; check whether this change has anything to do with gene methylation, or is just a question of stressed-out mothers.

      • James Chilton

        You mean design a rigorous scientific study. The data collected by Rachel Yehuda are miniscule and have not been repeatedly subjected to experiment and analysis that would weed out fanciful explanations.

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