Epigenetics and Historical Proxy theories in the intergenerational inheritance of Historical Trauma: “Who is telling the story? The genes or the mind?”

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10 gennaio, 2016 - 08:53


Trauma has been the focus of much research for more than three decades. This emphasis makes sense, since traumatic experiences have a profound effect on psychological and physical health not only for the individual, but for communities, and generations to come. Lately, this intergenerational effect has been postulated to be a result of a process called Epigenetics, representing multiple effects of environmental influences on individual genetic makeup.  The article focuses on the possible modalities of transmission of traumatic experiences among generations in Native American populations. Besides exploring the possibility of Epigenetics as a conduit for the transmission of Historical Trauma, it approaches the concept of Historical Proxy as an alternative explanation to Epigenetics, without asserting that the two are mutually exclusive.

The concept of  Historical Proxy , which was coined during  some of the work on  Historical trauma IIKD ( Indigenous Institute for Knowledge and Development), at the University Of New Mexico in Albuquerque, refers to the  effect of memories, facts, tales, images, places, circumstances, reenacting historical traumatic events  and triggering  emotional  and physical  distress. This theory, as well, is in need of validation, which, in the future, will be found in the analysis of qualitative work on the subject of Historical Trauma.

Therefore, the author proposes an alternative, but not an  adversary explanation, to the influence of Epigenetics on Historical Trauma by introducing  the concept of Historical Proxy  as a way of avoiding  a segregation of historical memories into  an epigenetic frame, which  still necessitates more investigation, and  risks to become  both a cliché and catchphrase, gaining acceptance without solid scientific evidence.

Background on Historical trauma

Although a definitive empirical conceptualization of historical trauma has to be reached yet, a working definition from the writing of Native American scholars views historical trauma as the psychological, physical, social and cultural aftermath of the process of colonialism and post colonialism to which Indigenous people have been subjected. The literature on historical trauma is huge, and its reality undeniable, even though mainstream academia is still resistant to accept the validity of its concept.  This resistance is based on philosophical, methodological, and in some cases on preconceived and prejudicial views regarding the validity of a concept, which ties colonial historical events to the development of psychological and physical distress.

In a previous article, I stated that Native American scholars view historical trauma as the psychological, physical, social and cultural aftermath of the process of colonialism and post colonialism to which Indigenous people have been subjected. I stated very clearly that to clarify the essential structure of historical trauma, it is necessary to describe two related, but at the same time, different entities: PTSD (Post Traumatic Stress Disorder) and Intergenerational Trauma, and more specifically Historical Trauma (1).

Native American scholars (i.e. Maria Brave Heart, Bonnie Duran, Eduardo Duran, Karina Walters, Tassy Parker, Lori Jervis,) have contributed to the development of the concept and frame of Historical Trauma basing their work on the historical events and experiences which have characterized the lives of the American Indians for more than five centuries. Their work falls within the tradition of the classical writing on the effects psychological impact of colonization, and those on psychological trauma caused by the Holocaust, different wars, epidemics, and deprivations, which have plagued the lives of numerous groups and entire populations.

The concept of Historical Trauma has developed as a natural consequence of tragic historical events affecting the psyche of Indigenous Peoples, and as a reaction to the narrow definition of trauma as expressed through the clinical entity of PTSD (1).

PTSD, in reality, describes the clinical symptoms following a circumscribed traumatic experience. These symptoms can be grouped in two main categories: the "intrusive" and the "numbing" manifestations of trauma. The "intrusive" category includes: hyperactivity, explosiveness, nightmares related to the traumatic event and flashbacks. In the "numbing" realm we find: social isolation, inability to explore pleasure or satisfaction, and avoidance of obligations (1). These two, summarily described, convey a mechanical-biological picture of trauma, evoking alternating phases of neuronal hyperactivity (intrusion) and hypo activity (numbing) (1).

However, experiences from the Holocaust, dictatorial regimes, episodes of ethnic cleansing, political persecution, etc., show that the consequences of trauma could, and often are, transferred from one generation to the next. The clinical manifestations are analogous to those witnessed in PTSD but extended in an intergenerational fashion, definable therefore as Intergenerational Trauma (3). But, although this entity definitely broadens the scope of the traumatic experience, it does not include an analysis of the historical context in which trauma originates and therefore is not sufficient to fully explain the psychic and physical damage deriving from the colonial and postcolonial experience in Indigenous populations (4).

Furthermore, the understanding of Historical Trauma implies, the evaluation of the experience of psychological "fragmentation" as a disruption of the necessary feeling of continuity with one’s culture and traditions, in the context of a colonial and postcolonial historical frame. The identification of this process needs to include a correct and thoughtful understanding of governmental Indigenous policies as subtler and insidious causes of trauma, because of their apparent legitimate political and legislative tone (2, 3, 4). The psychosocial consequences stemming from these vicissitudes can be expected as partially coinciding with the DSM (Diagnostic Statistical Manual) classification and list of signs and symptoms, but essentially reflecting an existential frame, not as amenable to an official medical/psychiatric taxonomy. Starting from the stated premises, we can formulate the following working outline for Historical Trauma

  1. A historical existential dimension, whose most salient characteristic is a sense of "not belonging", estrangement from the relationship with Indigenous cycle of life, definable in traditional sociological terms as Anomie (4).
  2. Another part, closely related to the PTSD nomenclature, occurring from more discrete traumatic situation, enacted in the background of specifically deleterious historical processes. Indeed, it is worthwhile to observe that a lot of the circumscribed traumatic events in Native country develop in a scenario of poverty, unemployment, and social injustice: They could be viewed as an appendix of historically traumatic events.

 The existential-historical-emotional manifestations, which are the essential features of historical trauma do not have the clearly defined boundaries of a clinical syndrome like PTSD because the "existential" is essentially personal, subjective, social, and political. The pathology, however, is no less real or painful: If anything, its manifestations raise the subject of the inadequacy of Western methodological screening and testing procedures of phenomena not happening within the realm of the dominant society (5). From the literature available, and the direct feedback of Native American scholars, and professionals, the existential-historical aspects of historical trauma could be summarized as follows (1):

  1. Communal feelings of disruption of the family and societal network,


  1. Development of an existential form of depression, based on a sense of communal disruption and anomie,


  1. Ambivalence and anxiety about feeling part of the historical ancestral pain, and the tempting option to adopt the easily accessible Western attitudes, values, and sociocultural models,


  1. Development of chronic existential grief, nested in the dominant context of denial and silence. This angst is typically manifested through the complete rubric of destructive and self-annihilating behaviors (including some pattern of drinking and substance abuse),


  1. The daily re-experience of colonial aspects of trauma stemming from stereotyping, and racism, which are the base for the above described emotional states, and


  1. Lack of resolution of the existential dimension triggering an individual, intergenerational, and communal experience of the described existential pain.

Intergenerational transmission: The power of the narrative and the function of Historical Proxy.

Despite the fact that most Indigenous communities have been touched to some extent by Historical Trauma, the degree to which individuals suffer from it and the number of those affected, is unknown. The types of trauma events suffered by the different Native tribes and communities is extremely variable, making it difficult, if not impossible, to generalize the reality of Historical Trauma across all Native communities and individuals. But, there are clearly historical events representing a common denominator across most Native tribes and communities: The ethnic genocide and forced assimilation, the experience of government-run boarding schools to assimilate Native American children by removing them from their families (6), and massive obliteration of traditional religion (6, 7). These events disrupted fundamental traditional patterns and resulted in cultural loss for subsequent generations, ultimately creating physical and mental problems for Native communities (8, 9).


The intergenerational transmission of trauma has been viewed for the most part as based on recollection of events, whose memory has been handed down from one generation to the next one, in the natural context of family and community values and habits, including the use of storytelling, sharing experiences, traditions, fundamental historical events specific to the community. However, although these modalities of sharing have a huge role in the genesis of trauma responses in younger generations, they do not fully explain as why individuals who were not explicitly part of this sharing of memory, events, can show signs of Historical Trauma ( i.e. helplessness, apathy, feelings of  detachment and alienation from their own communities).

Working with Indigenous researchers at IIKD (Indigenous Institute for Knowledge and Development) at the University Of New Mexico in Albuquerque, the author has looked into possible explanations for this issue by introducing the Historical Proxy effect.

The definition of proxy as indicated in different dictionaries can be summarized as “An agent legally authorized to act on behalf of another party”.

Based on the meaning of this definition, Historical Proxy can be conceptualized as a combination of symbols, events , actions, , etc., acting  on the human psyche as the real and original  historical event(s) and , as a consequence, triggering  feelings and  emotions,  independently from the individual’s knowledge of the specific event(s).

As cogently stated by some authors, the narrative of traumatic experiences is instrumental in connecting present-day experiences and circumstances to the original trauma, and therefore in understanding its impact on present-day experiences including its effects on psychological and physical health (10).

Of course the concept of Historical Proxy will need to be validated, but it could be argued that currently it is as plausible as the epigenetic theory on inheritance of traumatic memories.


The Epigenetic view:

More recently,  and probably  in the context of the quasi failure of  the data produced by the  genome project regarding  the search for a  biological basis of mental illness, the “movement” of Epigenetics has been  proposing that the memories of trauma experienced by our  ancestors are stored in our genetic makeup. According to this theory, the trauma experienced by previous generation can be etched in our genes to activate a dysfunctional response to stress and, therefore, heightening the possibility of the development of trauma related symptoms. (11)

Traditional genetic theories do not encompass the effects of the environment, and, as such, they consider the genome as the defining blueprint for the development of individual characteristics and pathologies, including mental illness.

Since the study of Epigenetics of mental illness has been in part based on rodent models (12, 13, 14), its implications regarding human experience need to be taken with caution. So far, our knowledge on the subject shows that the possibility of environmental induced epigenetic modifications is not consistently predictable, and therefore no conclusive pattern of transmission can be established. (15)

The core of   Epigenetics is about the establishment of changes including DNA methylation and acetylation, methylation and phosphorylation of histones and DNA-associated proteins. The effect of, methylation is paramount since contributes to gene expression. It is an important aspect, according to investigators in the fields, for the understanding the epigenetics influences on Historical Trauma. (11, 19)

The hope is that, the current investigations on the subject will reveal specific markers of mental health disorders. (15, 16, 17) However, it is unclear that epigenetic studies in the field of mental illness would be as productive as desired. One of the risk is that they may morph into insights reflecting a biological interpretation of the nature of mental illness, and therefore reinforcing the current dominant biological interpretation of emotional distress and mental illness.

The hypothesis of the epigenetic model is supported by the well-known effect of Adverse Childhood Experience (ACES) which, focusing on negative events during childhood, shows a negative impact on physical and mental health. (18)

One study showed a significant difference in the hippocampus between adult rats raised by attentive and inattentive mothers. “Adult offspring of inattentive rat mothers showed genes regulating sensitivity to stress to be highly methylated. The rats with attentive moms did not”. (11, 19)

The researchers switched the parents and saw that when the babies born to attentive moms were given to inattentive moms, they also developed highly methylated genes and grew to be restless adults. The opposite proved true for babies born to bad moms, given to good moms. As adults, the rat babies born to bad moms but raised by good mothers appeared calm. (11)

As consequence of this line of inquiry, it is not infrequent to read and hear during conversations among professionals and scientific meetings that the development of Historical Trauma is correlated to Epigenetics like diabetes, depression, and PTSD, and other mental disorders. Hopeful and enthusiastic views about Epigenetics are spreading fast among Historical Trauma specialists and authors, as well.

For example, LeManuel “Lee” Bitsoi, Navajo, PhD Research Associate in Genetics at Harvard University has stated that “Native healers, medicine people and elders have always known this” (referring to the impact of Epigenetic mechanisms on Historical Trauma). (20)

Also, Bonnie Duran, associate professor in the Department of Health Services at the University of Washington School of Public Health and Director for Indigenous Health Research at the Indigenous Wellness Research Institute said, “Many present-day health disparities can be traced back through Epigenetics to a “colonial health deficit,” the result of colonization and its aftermath.”(20)

The Native researcher Teresa Brockie PhD, Research Nurse Specialist at the National Institute of Health, claims that gene methylation is linked to health disparities among Native Americans.  She and her colleagues note that high ACE’s (Adverse Childhood Experience) scores have been linked to methylation of genes that regulate the stress response. And they postulate that, since Native peoples have high rates of ACE’s and health problems such as posttraumatic stress, depression, substance abuse, and diabetes, the methylation of genes could constitute a feasible biological basis for these conditions. (11)

However, although the modification of gene function through epigenetic influence can greatly impact the health of the individual and may underlie some of the health disparities in Native Americans, the paucity of studies providing definitive responses to this theory, makes it rather challenging, to establish a cause –effect relationship between epigenetics and high rates of specific disorders among Native Americans.

And although, several scholars are highlighting the historical and environmental aspects of the epigenetic theory of trauma, these and in particular those related to Historical Trauma, are just part of a theory in need of validation. In reality, a substantial number of the pivotal studies on Epigenetics have been conducted on rats.

 Hence, several authors feel that Epigenetics may be getting “ahead of itself”. Joseph Gone, Indigenous scholar at the University of Michigan states “There is a lot of research that needs to be done before we will understand whether and how these processes work,” (11)

Moreover, some speculate that this line of inquiry may inadvertently evoke the notion that Native peoples and other ethnic groups are genetically challenged.

Following this view, Shannon Sullivan, professor of philosophy at UNC Charlotte, suggests in her article that this “science has faint echoes of eugenics, the social movement claiming to improve genetic features of humans through selective breeding and sterilization”. (21)

Additionally, since the biological aspects of epigenetics constitute a potential source of huge profits for pharmaceutical companies (22, 23), these are actively searching for possible pharmacologic solutions to the methylation mechanisms allegedly implicated in the causation of mental disorders. Therefore, there is a distinct possibility that Historical Trauma could morph in a biological disorder, whose alleged basis, the methylation process, can be remedied by appropriate pharmacologic interventions.

But, moreover and most importantly, the relevance of the epigenetic studies regarding PTSD, may not be applicable to Historical trauma, as these two entities are not the same, even if some of their manifestations may overlap. (1) It is uncanny how the basic difference between PTSD and Historical Trauma has been ignored in the enthusiastic and biologically driven search for the applicability of epigenetic induced trauma theory to Historical Trauma.  Historical trauma and PTSD cannot be combined in one entity or viewed as stemming from the same root cause. Historical Trauma is dipped in history, and although the effects of historical experiences on epigenetics may be substantial, the contextual historical narrative has a symbolic, psychological, social, and spiritual valence, requiring cognitive, emotional and spiritual processing, before it can be, contextualized, categorized and “felt” as a historical traumatic event. More succinctly, Historical Trauma requires a context and a narrative (1, 2, 3, 4). Epigenetics, cannot provide such narrative.


Although Epigenetics represents an interesting shift from classical genetics, by emphasizing the effect of the environment on gene expression, its applicability to the field of mental health and in particular to the study of Historical Trauma is still premature. The author has attempted to compare two different, but not mutually exclusive explanations, for the intergenerational transmission of Historical Trauma: the concept of Historical Proxy and Epigenetics. But as the field of Historical Trauma continues to evolve, independently form etiologic views and disputes, it is essential to remember that its awareness has brought to the fore the spirit of resiliency of Native American and Indigenous people around the world. Their communities have consistently pursed the rediscovery and preservation of the most fundamental sociocultural and spiritual aspects of their heritage.

 The trend of cultural revival, has shown its beneficial effects, both physical and psychological, as reported by Indigenous scholars, who have shown that the preservation of health in Indigenous communities could not be found in the mechanical and biological nature of Western medicine, but in the traditional context of their historical and social narratives. Epigenetics and biological approaches, by themselves, will not be able to generate or regenerate these narratives. Deborah Bassett and colleagues have stated this concept succinctly and brilliantly in the title for their qualitative article on Trauma in Native Americans: “Our Culture Is Medicine”. (24)



(1). Maviglia, Marcello, (2002), Letter from the State. (In English and Italian) Historical Trauma and PTSD: The “Existential” versus the “Clinical”. Psychiatry On-Line, at: POL.IT. View on-line at:  http://www.psychiatryonline.it/ ital/fromstates2e.ht

(2).Brave Heart, M. & DeBruyn, L. (1998). The America Indian Holocaust: Healing historical unresolved grief. American Indian and Alaskan Native Mental Health Research, 8, 60-82.

(3). Berger, L (1988). The long-term psychological consequences of the Holocaust on survivors and their offspring. In R.L. Braham, (Ed), the psychological perspective of the Holocaust and of its aftermath (pp175-221). New York: Columbia University Press.

(4) Duran, E, & Duran B. (1995). Native American post-colonial psychology. Albany, NY: State University of New York.

(5) Pavkov, T. W., Lewis D. A., and Lyons, J. S. (1989). Psychiatric diagnosis and racial bias: An empirical investigation. Professional Psychology: Research & Practice 20:364-368.

(6) Weaver, H. N. (1998). Indigenous people in a multicultural society: Unique issues for human services. Social Work, 43(3), 203-211. Retrieved from http://www.naswpress.org/publications/ journals/sw.html

(7) Deloria, V., (1988). Custer died for your sins: An Indian manifesto. Norman, OK: University of Oklahoma Press.

(8) Stamm, B. H., Stamm, H. E., Hudnall, A. C., & Higson-Smith, C. (2004). Considering a theory of cultural trauma and loss. Journal of Loss and Trauma, 9, 89-111.

(9) Whitbeck, L. B., Adams, G. W., Hoyt, D. R., & Chen, X. (2004). Conceptualizing and measuring historical trauma among American Indian people. American Journal of Community Psychology, 33(3/4), 119-130.

(10) Mohatt, Nathaniel Vincent, et al. (2014):"Historical trauma as public narrative: A conceptual review of how history impacts present-day health." Social Science & Medicine 106 128-136.

(11) Mary Annette Pember (2015), Trauma May Be Woven Into DNA of Native Americans, ,5/28/15http://indiancountrytodaymedianetwork.com/trauma-may-be-woven-dna-native-americans-160508.

(12)Weaver IC, Cervoni N, Champagne FA, et al.( 2004), Epigenetic programming by maternal behavior. Nat Neurosci; 7:847-54.

(13), Colvis CM, Pollock JD, Goodman RH, et al.( 2005), Epigenetic mechanisms and gene networks in the nervous system. J Neurosci; 25:10379-89.

(14). Abdolmaleky HM, Smith CL, Faraone SV, et al.( 2004 Methylomics in psychiatry: modulation of gene–environment interactions may be through DNA methylation. Am J Med Genet B Neuropsychiatr Genet; 127:51-9.

(15) Madhani HD, Francis NJ, Kingston RE, et al. (2008), Epigenomics: A roadmap, but to where? Science; 322:43-4.

(16)Time for the epigenome. Nature 2010; 464:487.

(17) Ptashne M, Hobert O, Davidson E. (2010), Questions over the scientific basis of epigenome project. Nature; 464:487.

(18) Robert F. Anda, Vincent J. Felitti, J. Douglas Bremner,( 2006).The enduring effects of abuse and related adverse experiences in childhood. A convergence of evidence from neurobiology and epidemiology. European Archives of Psychiatry and Clinical Neuroscience, April, Volume 256, Issue 3, pp 174-186.

(19) Szyf M., (2009), Epigenetics, DNA methylation, and chromatin modifying drugs. Annu Rev Pharmacol Toxicol; 49:243-63.

(20) Kit O'Connell (2015), Native Americans Have ‘Always Known’: Science Proves Genetic Inheritance Of Trauma. http://www.mintpressnews.com/native-americans-have-always-known-science-proves-genetic-inheritance-of-trauma/208988

(21) Shannon Sullivan (2013), Inheriting Racist Disparities in Health: Epigenetics and the Transgenerational Effects of White Racism, Critical Philosophy of Race Volume 1, Issue 2. pp. 190-218

(22) K. John Morrow, Jr., (2013) Epigenetics Drives Pharma Innovation.Therapeutics targeting epigenetic mechanisms of disease will change the pharmaceutical marketplace, BioPharm International Volume 26, Issue 1

 (23)Epigenetics industry will generate $4,279m in 2018, predicts new study.https://www.visiongain.com/Press_Release/649/Epigenetics-industry-will-generate-4-279m-in-2018-predicts-new-study.

(24) Deborah Bassett, Ursula Tsosie, Sweetwater Nannauck (2012), “Our Culture Is Medicine”: Perspectives of Native Healers on Posttrauma Recovery Among American Indian and Alaska Native Patients. Perm J.; 16(1): 19–27.

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