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Inherited Trauma: Is It Real? Clues to Post Traumatic Slave Syndrome

May 31, 2021 04:51PM ● By Noah Chen

© Юрий Красильников

When he took a look at the world’s collection of religions, Swiss psychiatrist and founder of analytical psychology Carl Jung was amazed by the number of similarities and connections that could be drawn between unconnected cultures around the world. Jung sensed that there might be some force connecting humanity with the experiences of our collective ancestors. He named this force the “collective unconscious” and theorized that it was a bundle of images, emotions and memories of our ancestors’ experiences and that it could be useful in helping the current generation.

It is clear that our ancestors are important insofar as they supply our unique genetic code—except for identical twins whose code is not technically unique. Our genes are made up of DNA, half of which is supplied by the mother and half by the father, which shapes a good deal of our growth and development. It was originally thought that our genes and experiences did not interact—and, in turn, that how our ancestors chose to live or what they experienced would not impact our genetic inheritance.

However, recent discoveries in psychology and biology have uncovered a reality closer to Jung’s theories than many thought possible. Through the study of epigenetics, science is starting to recognize that it is not only possible that the broad tendencies of our ancestors shape our current psychology, but that traumas and specific sensitivities of an individual can be passed down through numerous generations. While the possibility of being closer to our ancestors is exciting for many, it does put one segment of America’s population in a complicated position.

Post Traumatic Slave Syndrome

The truth is that the familial past of many African Americans contains pain, trauma and heartbreak as a result of living in a racist environment. If the experiences of our ancestors can influence and shape our modern lives, then what does it mean for those whose families were forced to survive slavery, Jim Crow and our current American culture?

Author Dr. Joy DeGruy has spent years researching and writing about this very subject. In her seminal book, Post Traumatic Slave Syndrome: America’s Legacy of Enduring Injury & Healing, DeGruy draws a line of causation from the hostilities that white people enacted on their Black slaves to behaviors present in the Black community today that, DeGruy argues, have been passed down through the generations, sometimes intentionally to help the next generation survive, but sometimes in ways that are unintentional.

“Social learning theory posits that we learn from the people in our environment, not just in terms of what they are literally teaching us, but by what is being modeled,” says DeGruy. For Black Americans, according to DeGruy, this means that the learned and modeled behaviors typically have to do with surviving an “incredibly hostile environment.” It is these behaviors DeGruy points to as the effects of post traumatic slave syndrome.

While researching the book, DeGruy learned that not only were traumatic behaviors being passed down but so were genes that had been altered by that same trauma. “I started to study a little more about epigenetics,” DeGruy explains, referencing the recently emerging area of science that studies how interactions with our environment impact the expression of our genes. If someone is placed in a stressful environment for an extended period of time, for example, epigenetics predicts there will be some changes in that individual’s genetic expression.

DeGruy became especially interested in epigenetics because the changes to genetic expression can be passed down from generation to generation. She realized this meant that the trauma of slavery might still be encoded in the genes of many Black Americans today.

Courtesy Dr. Joy DeGruy

DeGruy recounts an experiment by Dr. Lei Cao-Lei and associates at the Douglas Mental Health University Institute and McGill University. They found that children of pregnant survivors of a 1998 snowstorm had a genetic tendency towards obesity—which may be attributed to that one specific traumatic experience their mothers had undergone. “These children weren’t there, and yet they are exhibiting different biological responses,” says DeGruy. “I had this moment where I was like, ‘Wow! What did hundreds of years of slavery do?’”

In their paper “Cultural Trauma and Epigenetic Inheritance,” Amy Lehrner and Rachel Yehuda summarize several other discoveries in the world of epigenetics and outline the genetic changes for which environmental interactions can be responsible. They note that a good deal of epigenetic research that focuses on inherited trauma looks at the hypothalamic-pituitary-adrenal (HPA) axis. This is our internal system that helps us respond to stress by releasing chemicals that assist the fight-or-flight response. The HPA axis is deactivated after the stressful element has been eliminated or evaded. It does so by releasing glucocorticoids and cortisol, compounds that help return the body to its non-threatened state.

A common way that epigenetic change manifests is through the mechanism of methylation, which occurs when a methyl group molecule (CH3) gets attached to DNA, modifying its function and how it is expressed. Dr. Kerry Ressler, a Harvard professor and epigenetic researcher, explains, “Adding that methyl group on the DNA causes other proteins to bind to the DNA in different ways and to read our genes in different ways.”

Studies that looked at the offspring of women who survived either intimate partner violence, warzone stress or the Rwandan genocide found that their HPA axis had been born methylated; they had inherited it from their mothers as a result of severe stress. The effect of the methylation is that both the mothers and offspring were more sensitive to stress and more likely to develop mental health disorders as a result of exposure to stress.

Stress Passed through the Generations

Ressler, working with Dr. Brian Dias, discovered that stress caused by an individual stimulus could be passed onto offspring as well. In their groundbreaking study, mice were taught to associate painful shocks with a powerful odor. Soon, the mice demonstrated a stress reaction to the smell alone, even when not being shocked. Dias and Ressler observed that their offspring also exhibited a similar stress reaction to the smell their parents grew to fear without ever having been shocked themselves.

Time and time again, with both humans and animals, studies have shown that an abundance of stress in the environment of the parent makes the child more likely to be sensitive to stress, which in turn creates a host of other health issues. While Dias and Ressler’s findings are specific to mice, and it is unclear how the results will generalize to humans, other researchers found epigenetic changes within the human body that persisted through multiple generations.

In their paper, Lehrner and Yehuda discuss findings that children of holocaust survivors who later experienced combat were more likely to develop post-traumatic stress disorder (PTSD), even though they had not experienced the holocaust themselves. This heightened sensitivity to stress was found to be the result of epigenetic DNA methylation. This concurs with other epigenetic research that broadly indicates that if an individual’s parents or even grandparents were under traumatic levels of stress, there is an increased likelihood that they will be more sensitive to stress and develop mental illnesses as a result of this sensitivity.

Everything is Subject to Change

While such epigenetic changes may have a negative effect as far as stress sensitivity is concerned, Ressler notes that those changes are likely not permanent. “Whatever is encoded at the epigenetic state should be manipulated or reversed at the epigenetic state,” says Ressler.

Ressler recommends that those who are more stress-sensitive place themselves in a supportive rather than a traumatic environment whenever possible. But, for some, that may prove easier said than done, as changing the American cultural environment to be more conducive to Black people flourishing would mean making extensive changes to many American institutions.

In terms of epigenetics, this means that reversing these trauma reactions on the genetic level is less likely to happen as long as the environment remains hostile. “You have people who say slavery is over,” says DeGruy. “Yeah, but the lynchings occurred. Most of the lynchings occurred after slavery. But you get this kind of mythology that slavery is ancient and everything is fine.” However, individuals and family units still have immense power to influence themselves and those for whom they care.

DeGruy recounts a story where her daughter’s white workplace superior put his hands on her hair without consent. “When my daughter said that this white man did that to her, every hair on my body stood up,” says DeGruy. “But my daughter said to me, ‘Mom, calm down. I got this.’ She said, ‘Thank you for not passing on your injury,’” recalls DeGruy. “There is a freeness that she has because I did not pass along that heaviness.”

A growing body of evidence now suggests that the experiences of our ancestors are encoded in our genetics and might influence a great deal in us, from a likelihood to develop mental illness to our distaste of certain smells. For certain Americans, this means the trauma of the past is alive today, and only time will tell if those wounds will ever be fully allowed to heal.

Noah Chen is a staff writer for the Atlanta franchise of Natural Awakenings. He also dabbles in screenwriting and video game script writing. 

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