In the dying days of World War Two, a grim famine struck in the Nazi-occupied part of the western Netherlands. Like a ghost in the genetic code, the legacy of this horror can still be seen in the DNA of hundreds of Dutch people who were still in their mother’s womb at the time.
During the six months of the Dutch Hunger Winter, between 1944 and 1945, around 20,000 people starved to death and some 4.5 million more were drastically undernourished. Among those were hundreds of pregnant women who were forced to survive on less than 900 calories a day.
It’s been noted that people born just after the Hunger Winter have had increased instances of obesity, type 2 diabetes, schizophrenia, and other chronic health problems. According to a new paper in the journal Science Advances, this is certainly no coincidence – it’s the result of epigenetic changes sparked by the intense hardship they experienced while still in utero
Epigenetics, meaning “on top of genetics,” explains how genes can get turned on or off, irrespectively of the underlining genetic code itself. Although you might think the genetic code is set in stone, certain environmental factors can change how these genes express themselves. This means that environmental stimulus, such as diet or trauma, can switch certain genes on or off like a dimmer switch.
A common mechanism for epigenetic changes is DNA methylation, which involves the addition of methyl groups to certain bits of DNA. Stress, such as an extreme famine, could alter the methylation patterns, even perhaps while you’re still in the womb.
Scientists from the Netherlands and the US investigated this by studying 422 people were exposed to the famine in utero and looking for any evidence of epigenetic changes that later affected their adult health.
After comparing the 442 individuals to their 463 siblings who weren’t exposed to the stress in the womb, the researchers found that DNA methylation had made changes near six additional genes that control metabolism and cell differentiation during development. It seems the stress of the famine turned off the genes of unborn children, leading them to suffer from an array of health conditions effecting their metabolism.
“We show that associations between exposure to an adverse environment during early development and health outcomes six decades later can be mediated by epigenetic factors,” LH Lumey, professor of Epidemiology at Columbia’s Mailman School of Public Health, said in a statement.
The Dutch Hunger Winter was one of the worst famines to take place in a 20th-century developed nation, meaning that it’s also one of the best-documented famines in recent history. Now, with a better understanding of genetics under our belt, it could serve as an incredible opportunity to study the effect of a society’s widespread trauma on epigenetic changes and health.