Epigenetics
Epigenetics
Embedded Files
In recent years a new field has emerged that studies how the historical experience of your progenitors impacts your gene expression. Not only is your mother's hair color, but the traumatic events she may have endured are influential on your biological makeup and development. Such traumatic experiences will not actually change the genetic code but will dictate which genes are expressed for generations. A striking characteristic of epigenetics is its similarity to evolution, in terms of heritability. However, unlike evolution, there is a strong argument that epigenetics is not beneficial to the subject while evolution is.
"Toxic" Stress
"Toxic" Stress
Stress is a normal phenomenon that humans evolved to experience to increase their chances of survival. If a human reacted to a dangerous animal without any fear or stress, humans would not have lived very long. However, if the brain is constantly firing up a stress response the brain becomes damaged. This damage from chronic stress is referred to as "toxic stress." One cannot overcome the impacts of toxic stress with a vacation or massage. There are long-lasting effects on your nervous system, heart, brain, immune system, and even DNA. Children who experience chronic toxic stress—such as those who grew up in an abusive household—are more likely to suffer from a plethora of diseases throughout their lives. More alarmingly, this toxic stress will change their DNA leading to future generations' genomes being expressed differently.
Historical Case Studies
Historical Case Studies
Epigenetics and American Slavery
Epigenetics and American Slavery
In recent years a new term "cultural PTSD" has come into use. That is, the inherited—genetic and environmental—trauma. In the United States, the research on this topic has been especially prevalent in the Black community around the discussion of the lasting impacts of the trans-Atlantic slave trade. In 2005 the clinical psychologist Joy Degruy published the book Post Traumatic Slave Syndrome an analysis of how the intergenerational trauma experienced by the African-American community continues to have negative effects today. Not only are there genetic differences that can be traced back to the trauma of slavery, but the African-American culture has evolved differently due to the centuries of terror inflicted on them.
A few marked symptoms of "post-traumatic slave syndrome" that Dr. Degruy points to are underdeveloped self-esteem, predisposition to violence or anger disorders, and internalized racism.
Epigenetics and British-induced Indian Famine
Epigenetics and British-induced Indian Famine
"...population metabolic differences have arisen through differential ancestral exposure to cycles of “feast and famine”, generating differential susceptibility to diabetes in modern environments..."
During the British occupation of India, famine occurrence spiked. Due to both the British's poor response to natural famine cycles and the intentional induction of famines via the stealing of crops and resources. During this time Indians' metabolism evolved the food scarcity to improve chances of survival. However, in present day the evolution has led to an epidemic of type 2 diabetes which has become more prevalent in India with Indians developing diabetes at lower weights and younger ages than other regions.
Biological studies
Biological studies
In a study done on worms from 2017, scientists found that gene expression was impacted for at least fourteen generations due to the exposure of a worm to a particular environment.
"Resident animals are not the only ones subject to their environment; their progeny can also be affected. For example, starvation or exposure to high temperature in Caenorhabditis elegans can lead to altered small RNA transmission and putative target mRNA expression for up to three generations..."
Such discoveries lead to questions about how the exposure of a community to a traumatic environment will continue to change generations of genomes and culture. This paper dubs this phenomenon "long-lasting epigenetic memory."If a group of people's DNA is changed due to their environment, their culture will also be changed and possibly stunted.
Researchers have studied orphans in Pakistani orphanages, descendants of Holocaust survivors, and mice to discover the health impacts of emotional trauma on future generations. They have shorter life expectancy and higher rates of diabetes and schizophrenia.
"But the human studies faced an obvious objection: The trauma could have been transmitted through parenting rather than epigenetics. Something about the experience [of traumatized persons], for example, might have made those [traumatized persons] poor [parents], to the detriment of their [children's] lives. The psychological impact of growing up with a parent who starved as a child or survived the Holocaust could itself be enough to shape a child's behavior."
This brings us back to our original nature vs nurture argument. As Cultural Studies warns, the biggest criticism of epigenetics is biological reductionism. However, in this case, mice studies come to the rescue to isolate the biological experience. Researchers traumatized infant mice—replicating abandonment and neglect situations—but only traumatized the male mice who then when on to mate with untraumatized female mice. Therefore, the trauma would be passed to a child who would be raised only by an untraumatized parent and in a community of mice who were not part of the experiment. The results of this experiment were that even when the environmental variable was completely ruled out, the descendants of the traumatized fathers still displayed more depressive and anxious—overall traumatized—behavior.
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