The legacy of unimaginable trauma has left its mark on the DNA of people who survived the 1994 Rwandan genocide. Most jarringly, the marks of this psychological trauma left in the genome were also passed down to the next generation and could be found in the DNA of offspring who weren’t even born at the time of the horror.
The first-of-its-kind study was recently published in the journal Epigenomics.
Scientists from the University of South Florida and the University of Rwanda studied the entire genomes of Tutsi women who were pregnant and living in Rwanda at the time of the genocide, as well as their offspring, and compared their DNA to other Tutsi women and their offspring who were living in other parts of the world at the time of the genocide.
DNA is sometimes seen as a hardwired code, but the expression of certain genes can be altered through epigenetic changes, which are influenced by lifestyle, experiences, and our environment. In the pregnant women who had experienced the terror of the genocide, the researchers found chemical modifications to the DNA that have previously been linked to a risk for mental health conditions, such as PTSD and depression. These same signatures were also found in the offspring who were a fetus at the time, indicating the epigenetic changes had been passed on.
“Epigenetics refers to stable, but reversible, chemical modifications made to DNA that help to control a gene’s function,” Professor Monica Uddin, lead study author from the University of South Florida, said in a statement. “These can happen in a shorter time frame than is needed for changes to the underlying DNA sequence of genes. Our study found that prenatal genocide exposure was associated with an epigenetic pattern suggestive of reduced gene function in offspring.”
To understand the depth of the trauma, it’s important to appreciate just how brutal the Rwandan genocide was. An estimated 1 million people were slaughtered over the course of 100 days between April and July 1994 during the Rwandan Civil War. Sexual violence was also rife, with an estimated 150,000 to 250,000 women being raped during the crisis.
The majority of the victims were Tutsi — a minority ethnic group that had historically dominated the country’s power structure — and perpetrators were primarily Hutus — an ethnic group that seized power in the 1959–1962 revolution. In 1990, an exiled Tutsi rebel group, the Rwandan Patriotic Front, attempted to grab back power and the civil war ignited. While a peace treaty was reached in 1993, the country redescended into chaos on the night of April 6 1994 when a plane carrying Hutu President Juvénal Habyarimana was shot down by a rocket. Hutu nationalists immediately launched an organized campaign of extreme violence against the Tutsis and their sympathizers, with local militias and the Hutu government inciting ordinary citizens to commit atrocities against their neighbors.
Speaking about this latest study, researcher Professor Derek Wildman noted: “The Rwandan people who are in this study and community as a whole really want to know what happened to them because there’s a lot of PTSD and other mental health disorders in Rwanda and people want answers as to why they’re experiencing these feelings and having these issues.”
While this is the first genetic study to see how the genocide affected people in Rwanda, previous studies have reached similar findings regarding other ruinous events in world history. In 2018, one study looked at victims of a famine that struck Nazi-occupied Netherlands during the dying days of World War Two. Much like this new study in Rwanda, they found that epigenetic changes sparked by the intense hardship they experienced while still in utero, likely explained why people born just after the so-called Hunger Winter had an array of health problems.