A Historian Reflects on Epigenetics
by Laura Stokes
7 January 2015
I have recently fallen into discussions about the shape of history and the pace of human experience. My historical expertise focuses on Swiss city-states in the fifteenth and sixteenth centuries, where medieval mentalities were being powerfully transformed and the basic contours of a modern mindset were being laid. Cities are my petri dishes, but the organisms under my examination are also the ones responsible for creating and maintaining the boundaries of their system. Their techniques, from quarantine to toll gates, were so flawed as to become at times counterproductive by modern standards. Despite all that messiness, late medieval cities are excellent communities to study because they had sufficient density of habitation and firmness of boundaries to compel social cooperation. The burghers had to resolve all the hazards of the petri dish, from the fundamental problem of waste through particularly human problems such as the conflict between liberty and social responsibility. Human societies adapt and change, as do the social and collective lives of all species, but we are perhaps unique in our self-consciousness of that change. We not only think historically, we also dream of better futures and take action to reach them. Historians study the details, but we do so in order to describe the meaning and shape of the past. Our material is only dimly and imprecisely seen, and our descriptions of the object of examination are often better when they are done with the messiness of intuition that comes from complete immersion in the detail.
We cannot afford to work with a flawed understanding of the structural constraints of the human species. One sociobiological approach posits that if our bodies evolve by the slow processes of genetic drift and speciation, and given that our basic emotional responses are physiologically rooted in the brain, then by a series of such connections, the basic structures of society are bound to change on an evolutionary scale: so very slowly as to be imperceptible at the historical scale. Most historians protest against such a dehumanizing structuralism. Some humanists accuse scientists of committing an error of determinism in seeing hard connections between biology and culture. The error is not in seeing a connection between human bodies and human societies, however, for such is undeniable. The error lies in assuming that each layer of the system fully determines what happens in the next layer. Where such thinking exists, it reflects a failure to grasp the full implications of the physical dictum of mutual effect (Newton’s third law): bodies affect cultures and therefore cultures affect bodies. The exact nature of these connections is only scarcely grasped and will no doubt provide material for centuries of human inquiry.
In fact, the pace of history is not bound to an evolutionary time scale. Human beings can transform their mentalities and shift their structural boundaries within a single lifetime; societies can do it within a few generations. Deep structures usually do change much more slowly than this, on the scale of millennia perhaps. We also share some basic structures with our mammalian cousins, and it seems reasonable to suppose that we inherited them from our shared ancestors. The amygdala does not appear much transformed; it is in other parts of the human brain that we manage our complex emotional, social, and intellectual lives.
Our brains are, of course, also affected by our complex lives. Thus we have learned that trauma can leave physical transformations in the brain, changes that predispose the victim to negative emotional states and future fragility in the face of trauma. We have learned also, that some of these physical transformations are epigenetic changes that are heritable from one generation to the next, so that the children of a trauma sufferer may be predisposed to such fragility. Thankfully, we have also read that some negative epigenetic changes may fade away after a few generations, so we are not doomed to inevitable suffering. In fact, recent research has also shown that profound healing is possible even for seemingly intractable cases of post-traumatic stress disorder, using new therapies that integrate brain chemistry and human interaction in key ways.
When I think of all this, I think that trauma is not just an individual matter. The trauma of an individual impacts her family, her community, and her society. A child may be born into poverty in Montreal and also be in need of healing for an injury he is born with, a neurophysiological predisposition to antisocial emotional responses of fear and anger. Aid workers returning from Darfur admit in confidence that some people there seem so powerfully predisposed to violence that peace is unthinkable.* If it were possible to heal collective trauma the way we can heal individual trauma, would it be possible to bring cycles of violence to an end?
This was the question that led Richard Rockefeller and Kim Hailey to conversations about MDMA, PTSD, and humanitarian intervention. When the two drew me into their discussions, I launched research into the social and intergenerational aspects of mass trauma, discovering a rich academic literature that is often highly critical of past interventions. We’ve been enmeshed in a continuing conversation of increasing diversity and vigor ever since. When Richard Rockefeller died this past June, our research group decided to plan a conference in his memory, Soul Wounds: Trauma and Healing across Generations (June 4-6, 2015, Stanford University).
*via journalist Francisco Toro in private correspondence on 15 June 2014.
Laura Stokes is an Associate Professor of History at Stanford University and the director of the Stanford Research Group on Collective Trauma and Healing.