One of the better books on trauma I’ve seen is by Resmaa Menakem. He is a trauma therapist with a good range of personal and professional experience, which allows him to persuasively combine science with anecdotes. I heard him speak at Prairie Lights bookstore. He was at the end of his book tour and, instead of reading from his book My Grandmother’s Hands, he discussed what inspired it.
He covered his experience working with highly traumatized contract workers on military bases in Afghanistan. And he grounded it with stories about his grandmother. But more interestingly, he mentioned a key scientific study (see note 15 below). Although I had come across it before, I had forgotten about it. Setting up his discussion, he asked the audience, “Have any of you been to Washington, DC and smelled the cherry blossoms?” He described the warm, pleasant aroma. And then he gave the details of the study.
Mice were placed in a special enclosure. It was the perfect environment to fulfill a mouse’s every need and desire. But the wire mesh on the bottom was connected to electrical wires. The researchers would pump in the smell of cherries and then switch on the electricity. The mice jumped, ran around, clambered over each other, and struggled to escape — what any animal, including humans, would do in a similar situation. This was repeated many times, until finally the mice would have this Pavlovian response to cherry smell alone without any electric shock.
That much isn’t surprising. Thousands of studies have demonstrated such behavioralism. Where it gets intriguing is that the mice born to these traumatized mice also responded the same way to the cherry smell, despite never having been shocked. And the same behavior was observed with the generation of mice following that. Traumatic memory to something so specific as a smell became internalized and engrained within the body itself, passed on through genetics (or, to be specific, epigenetics). It became free-floating trauma disconnected from its originating source.
Menakem asked what would another scientist think who came in after the initial part of the study. The new scientist would not have seen the traumatizing shocks, but instead would only observe the strange response to the smell of cherries. Based on this limited perspective, this scientist would conclude that there was something wrong with those mice. From the book, here is how he describes it in human terms:
“Unhealed trauma acts like a rock thrown into a pond; it causes ripples that move outward, affecting many other bodies over time. After months or years, unhealed trauma can appear to become part of someone’s personality. Over even longer periods of time, as it is passed on and gets compounded through other bodies in a household, it can become a family norm. And if it gets transmitted and compounded through multiple families and generations, it can start to look like culture.”
This is a brilliant yet grounded way of explaining trauma. It goes beyond a victimization cycle. The trauma gets passed on, with or without a victimizer to mediate the transmission, although typically this process goes hand in hand with continuing victimization. Trauma isn’t a mere psychological phenomenon manifesting as personal dysfunction. It can become embodied and expressed as a shared experience, forming the background to the lives, relationships, and communities within an entire society — over the centuries, it could solidify into a well-trod habitus and entrenched social order. The personal becomes intergenerational becomes historical.
This helps explain the persistence of societal worldviews and collective patterns, what most often gets vaguely explained as ‘culture’. It’s not just about trauma for anything can be passed on in similar ways, such as neurocognitive memes involving thought, perception, and behavior — and it is plausible that, whether seeming harmful or beneficial, much of this is supported by epigenetic mechanisms in contributing to specific expressions of nature-nurture dynamics. Related to this, Christine Kenneally offers a corroborating perspective (The Invisible History of the Human Race, Kindle Locations 2430-2444):
“It seemed that both families and social institutions matter but that the former is more powerful. The data suggested that a region might develop its own culture of distrust and that it could affect people who moved into that area, even if their ancestors had not been exposed to the historical event that destroyed trust in the first place. But if someone’s ancestors had significant exposure to the slave trade, then even if he moved away from the area where he was born to an area where there was no general culture of mistrust, he was still less likely to be trusting. Indeed, Nunn and Wantchekon found evidence that the inheritance of distrust within a family was twice as powerful as the distrust that is passed down in a community.”
Kenneally doesn’t frame this according to epigenetics. But that would be a highly probable explanation, considering the influence happens mostly along familial lines, potentially implying a biological component. Elsewhere, the author does mention it in passing, using the same mouse study along with a human study (Kindle Locations 4863-4873):
“The lives that our parents and grandparents lived may also affect the way genetic conditions play out in our bodies. One of the central truths of twentieth-century genetics was that the genome is passed on from parents to child unaffected by the parents’ lives. But it has been discovered in the last ten years that there are crucial exceptions to this rule. Epigenetics tells us that events in your grandfather’s life may have tweaked your genes in particular ways. The classic epigenetics study showed that the DNA of certain adults in the Netherlands was irrevocably sculpted by the experience of their grandparents in a 1944 famine. In cases like this a marker that is not itself a gene is inherited and plays out via the genes. More recent studies have shown complex multigenerational effects. In one, mice were exposed to a traumatic event, which was accompanied by a particular odor. The offspring of the mice, and then their offspring, showed a greater reactivity to the odor than mice whose “grandparents” did not experience such conditioning. In 2014 the first ancient epigenome, from a four-thousand-year-old man from Greenland, was published. Shortly after that, drafts of the Neanderthal and Denisovan epigenomes were published. They may open up an entirely new way to compare and contrast our near-relatives and ancestors and to understand the way that they passed down experiences and predispositions. As yet it’s unclear for how many generations these attachments to our genes might be passed down.”
In emphasizing this point, she continues her thought with the comment that (Kindle Locations 4874-4876), “Even given our ability to read hundred of thousands of letters in the DNA of tens of thousands of people, it turns out that— at least for the moment— family history is still a better predictor of many health issues. For example, it is the presence of a BRCA mutation plus a family history of breast cancer that most significantly raises a woman’s risk of the disease.”
Much of that ‘family history’ would be epigenetic or else other biological mechanisms such as stress-induced hormones within the fetal environment of the womb. Also, microbiomes are inherited and have been proven to alter epigenetics, which means the non-human genes of bacteria can alter the expression of human genes (this can be taken a further step back, since presumably bacterial genetics also involve epigenetics). Besides all of this, there is much else that gets passed on by those around us, from viruses to parasites.
Another pathway of transmission would be shared environmental conditions, specifically considering that people tend to share environments to the degree their relationships are close. Those in the same society would have more shared environment than those in other societies, those in the same community moreso than those in other communities in the same society, those in the same neighborhood moreso than those in other neighborhoods in the same community, and those in the same family moreso than those in other families in the same neighborhood. The influence of environments is powerfully demonstrated with the rat park research. And the environmental factors easily remain hidden, even under careful laboratory conditions.
What we inherit is diverse and complex. But inheritance isn’t fatalism. Consider another mouse study involving electric shocks (Genetic ‘switch’ for memories, The Age), showing that the effects of trauma can be epigenetically reversed within the body:
“Both sets of mice were trained to fear a certain cage by giving them a mild electric shock every time they were put inside.
“Mice whose Tet1 gene was disabled learned to associate the cage with the shock, just like the normal mice. However, when the mice were put in the cage without an electric shock, the two groups behaved differently.
“To the scientists’ astonishment, mice with the Tet1 gene did not fear the cage because their memory of being hurt had already been replaced by new information. The mice with the disabled gene, whose memories had not been replaced, were still traumatised by the experience.”
Trauma isn’t a personal failing or weakness. In a sense, it isn’t even personal. It’s a biological coping mechanism, passed on from body to body, across generations and centuries. Trauma is a physical condition, based on a larger context of environmental conditions. And maybe one day we will be able to as easily treat it as any other physical condition. In turn, this could have a profound impact on so much of what has been considered ‘psychological’ and ‘cultural’. There are immense implications for the overlap of personal healthcare and public health.
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My Grandmother’s Hands: Racialized Trauma and the Pathway to Mending Our Hearts and Bodies
by Resmaa Menakem
Chapter 3 Body to Body, Generation to Generation
“Not to know what happened before you were born is to remain forever a child.”
“No man can know where he is going unless he knows exactly where he has been and exactly how he arrived at his present place.”
Most of us think of trauma as something that occurs in an individual body, like a toothache or a broken arm. But trauma also routinely spreads between bodies, like a contagious disease. […]
It’s not hard to see how trauma can spread like a contagion within couples, families, and other close relationships. What we don’t often consider is how trauma can spread from body to body in any relationship.
Trauma also spreads impersonally, of course, and has done so throughout human history. Whenever one group oppresses, victimizes, brutalizes, or marginalizes another, many of the victimized people may suffer trauma, and then pass on that trauma response to their children as standard operating procedure. 13 Children are highly susceptible to this because their young nervous systems are easily overwhelmed by things that older, more experienced nervous systems are able to override. As we have seen, the result is a soul wound or intergenerational trauma. When the trauma continues for generation after generation, it is called historical trauma. Historical trauma has been likened to a bomb going off, over and over again.
When one settled body encounters another, this can create a deeper settling of both bodies. But when one unsettled body encounters another, the unsettledness tends to compound in both bodies. In large groups, this compounding effect can turn a peaceful crowd into an angry mob. The same thing happens in families, especially when multiple family members face painful or stressful situations together. It can also occur more subtly over time, when one person repeatedly passes on their unsettledness to another. In her book Everyday Narcissism, therapist Nancy Van Dyken calls this hazy trauma: trauma that can’t be traced back to a single specific event.
Unhealed trauma acts like a rock thrown into a pond; it causes ripples that move outward, affecting many other bodies over time. After months or years, unhealed trauma can appear to become part of someone’s personality. Over even longer periods of time, as it is passed on and gets compounded through other bodies in a household, it can become a family norm. And if it gets transmitted and compounded through multiple families and generations, it can start to look like culture.
But it isn’t culture. It’s a traumatic retention that has lost its context over time. Though without context, it has not lost its power. Traumatic retentions can have a profound effect on what we do, think, feel, believe, experience, and find meaningful. (We’ll look at some examples shortly.)
What we call out as individual personality flaws, dysfunctional family dynamics, or twisted cultural norms are sometimes manifestations of historical trauma. These traumatic retentions may have served a purpose at one time—provided protection, supported resilience, inspired hope, etc.—but generations later, when adaptations continue to be acted out in situations where they are no longer necessary or helpful, they get defined as dysfunctional behavior on the individual, family, or cultural level.
The transference of trauma isn’t just about how human beings treat each other. Trauma can also be inherited genetically. Recent work in genetics has revealed that trauma can change the expression of the DNA in our cells, and these changes can be passed from parent to child. 14
And it gets weirder. We now have evidence that memories connected to painful events also get passed down from parent to child—and to that child’s child. What’s more, these experiences appear to be held, passed on, and inherited in the body, not just in the thinking brain. 15 Often people experience this as a persistent sense of imminent doom—the trauma ghosting I wrote about earlier.
We are only beginning to understand how these processes work, and there are a lot of details we don’t know yet. Having said that, here is what we do know so far:
- A fetus growing inside the womb of a traumatized mother may inherit some of that trauma in its DNA expression. This results in the repeated release of stress hormones, which may affect the nervous system of the developing fetus.
- A man with unhealed trauma in his body may produce sperm with altered DNA expression. These in turn may inhibit the healthy functioning of cells in his children.
- Trauma can alter the DNA expression of a child or grandchild’s brain, causing a wide range of health and mental health issues, including memory loss, chronic anxiety, muscle weakness, and depression.
- Some of these effects seem particularly prevalent among African Americans, Jews, and American Indians, three groups who have experienced an enormous amount of historical trauma.
Some scientists theorize this genetic alteration may be a way to protect later generations. Essentially, genetic changes train our descendants’ bodies through heredity rather than behavior. This suggests that what we call genetic defects may actually be ways to increase our descendants’ odds of survival in a potentially dangerous environment, by relaying hormonal information to the fetus in the womb.
The womb is itself an environment: a watery world of sounds, movement, and human biochemicals. Recent research suggests that, during the last trimester of pregnancy, fetuses in the womb can learn and remember just as well as newborns. 16 Part of what they may learn, based on what their mothers go through during pregnancy, is whether the world outside the womb is safe and healthy or dangerous and toxic. […]
Zoë Carpenter sums this up in a simple, stark observation:
Health experts now think that stress throughout the span of a woman’s life can prompt biological changes that affect the health of her future children. Stress can disrupt immune, vascular, metabolic, and endocrine systems, and cause cells to age more quickly. 17 […]
These are the effects of trauma involving specific incidents. But what about the effects of repetitive trauma: unhealed traumas that accumulate over time? The research is now in: the effects on the body from trauma that is persistent (or pervasive, repetitive, or long-held) are significantly negative, sometimes profoundly so. While many studies support this conclusion, 19 the largest and best known is the Adverse Childhood Experiences Study (ACES), a large study of 17,000 people 20 conducted over three decades by the Centers for Disease Control and Prevention (CDC) and the healthcare conglomerate Kaiser Permanente. Published in 2014, ACES clearly links childhood trauma (and other “adverse childhood events” involving abuse or neglect 21) to a wide range of long-term health and social consequences, including illness, disability, social problems, and early death—all of which can get passed down through the generations. The ACE study also demonstrates a strong link between the number of “adverse childhood events” and increased rates of heart disease, cancer, stroke, diabetes, chronic lung disease, alcoholism, depression, liver disease, and sexually transmitted diseases, as well as illicit drug use, financial stress, poor academic and work performance, pregnancy in adolescence, and attempted suicide. People who have experienced four or more “adverse events” as children are twice as likely to develop heart disease than people who have experienced none. They are also twice as likely to develop autoimmune diseases, four and a half times as likely to be depressed, ten times as likely to be intravenous drug users, and twelve times as likely to be suicidal. As children, they are thirty-three times as likely to have learning and behavior problems in school.
Pediatrician Nadine Burke-Harris offers the following apt comparison: “If a child is exposed to lead while their brain is developing, it affects the long-term development of their brain . . . It’s the same way when a child is exposed to high doses of stress and trauma while their brain is developing . . . Exposure to trauma is particularly toxic for children.” In other words, there is a biochemical component behind all this.
When people experience repeated trauma, abuse, or high levels of stress for long stretches of time, a variety of stress hormones get secreted into their bloodstreams. In the short term, the purpose of these chemicals is to protect their bodies. But when the levels of these chemicals 22 remain high over time, they can have toxic effects, making a person less healthy, less resilient, and more prone to illness. High levels of one or more of these chemicals can also crowd out other, healthier chemicals—those that encourage trust, intimacy, motivation, and meaning. […]
The results of the ACE study are dramatic. Yet it covered only fifteen years. How much more dramatic might the results be for people who have experienced (or whose ancestors experienced) centuries of enslavement or genocide? 23
Historical trauma, intergenerational trauma, institutionalized trauma (such as white-body supremacy, gender discrimination, sexual orientation discrimination, etc.), and personal trauma (including any trauma we inherit from our families genetically, or through the way they treat us, or both) often interact. As these traumas compound each other, or as each new or recent traumatic experience triggers the energy of older experiences, they can create ever-increasing damage to human lives and human bodies.
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13 Over time, roles can switch and the oppressed may become the oppressors. They then pass on trauma not only to their children, but also to a new group of victims. 14 This research has led to the creation of a new field of scientific inquiry known as epigenetics, the study of inheritable changes in gene expression. Epigenetics has transformed the way scientists think about genomes. The first study to clearly show that stress can cause inheritable gene defects in humans was published in 2015 by Rachel Yehuda and her colleagues, titled “Holocaust Exposure Induced Intergenerational Effects n FKBP5 Methylation” ( Biological Psychiatry 80, no. 5, September, 2016: 372–80). (Earlier studies identified the same effect in animals.) Yehuda’s study demonstrated that damaged genes in the bodies of Jewish Holocaust survivors—the result of the trauma they suffered under Nazism—were passed on to their children. Later research confirms Yehuda’s conclusions.
15 A landmark study demonstrating this effect in mice was published in 2014 by Kerry Ressler and Brian Dias (“Parental Olfactory Experience Influences Behavior and Neural Structure in Subsequent Generations,” Nature Neuroscience 17: 89–96). Ressler and Dias put male mice in a small chamber, then occasionally exposed them to the scent of acetophenone (which smells like cherries)—and, simultaneously, to small electric shocks. Eventually the mice associated the scent with pain; they would shudder whenever they were exposed to the smell, even after the shocks were discontinued. The children of those mice were born with a fear of the smell of acetophenone. So were their grandchildren. As of this writing, no one has completed a similar study on humans, both for ethical reasons and because we take a lot longer than mice to produce a new generation.
16 A good, if very brief, overview of these studies appeared in Science: http://www.sciencemag.org/news/2013/08/babies-learn-recognize-words-womb .
17 This quote is from an eye-opening article in The Nation, “What’s Killing America’s Black Infants?”: https://www.thenation.com/article/whats-killing-americas-black-infants . Carpenter also notes that in the United States, Black infants die at a rate that’s over twice as high as for white infants. In some cities, the disparity is much worse: in Washington, DC, the infant mortality rate in Ward 8, which is over 93 percent Black, is ten times the rate in Ward 3, which is well-to-do and mostly white. […]
19 See, for example: “Early Trauma and Inflammation” ( Psychosomatic Medicine 74, no. 2, February/March 2012: 146–52); “Chronic Stress, Glucocorticoid Receptor Resistance, Inflammation, and Disease Risk” ( Proceedings of the National Academy of Sciences 109, no. 16, April 17, 2012: 5995–99); and “Adverse Childhood Experiences and Adult Risk Factors for Age-Related Disease: Depression, Inflammation, and Clustering of Metabolic Risk Markers” ( Archives of Pediatrics and Adolescent Medicine 163, no. 12, December 2009: 1135–43).
20 Of the people studied, 74.8 percent were white; 4.5 percent were African American; 54 percent were female; and 46 percent were male.
21 The ten “adverse childhood events” are divorced or separated parents; physical abuse; physical neglect; emotional abuse; emotional neglect; sexual abuse; domestic violence that the child witnessed; substance abuse in the household; mental illness in the household; and a family member in prison.
22 These chemicals are cortisol, adrenaline, and norepinephrine. They are secreted by the adrenal gland.
23 Please don’t imagine that we African Americans claim to have cornered the market on adverse childhood experiences. In fact, in his brilliant book Hillbilly Elegy: A Memoir of a Family and Culture in Crisis (New York: HarperCollins, 2016), white Appalachian J. D. Vance cites the ACE study in reference to himself, his sister Lindsay, and “my corner of the demographic world”: working-class Americans. As Vance notes, “Four in every ten working-class people had faced multiple instances of childhood trauma.” If you want to deeply understand the hearts, psyches, and bodies of many Americans today, you can do no better than to read both Hillbilly Elegy and Ta-Nehisi Coates’s Between the World and Me (New York: Spiegel & Grau, 2015).
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“What white bodies did to Black bodies they did to other white bodies first.”
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From Genetic Literacy Project:
Childhood trauma: The kids are not alright and part of the explanation may be linked to epigenetics
Your DNA may have been altered by childhood stress and traumas
Childhood trauma leaves mark on DNA of some victims
Is the genetic imprint of traumatic experiences passed on to our children?
Do parents pass down trauma to their children?
Was trauma from Holocaust passed on to children of survivors?
Holocaust survivors studied to determine if trauma-induced mental illness can be inherited
Epigenetics, pregnancy and the Holocaust: How trauma can shape future generations
Epigenetic inheritance: Holocaust survivors passed genetic marks of trauma to children
How epigenetics, our gut microbiome and the environment interact to change our lives
Skin microbiomes differ largely between cultures, more diverse sampling is needed
Cities have unique microbiome ‘fingerprint,’ study finds
Your microbiome isn’t just in you: It’s all around you
Microbes, like genes, pass from one generation to next
Microbiome profile highlights diet, upbringing and birth
Baby’s microbiome may come from mom’s mouth via placenta