The Great Depression, which, according to American history led to the worst recession, allegedly shaped people’s DNA before they were even born. According to a new study published in the Proceedings of the National Academy of Sciences in November, the cells of people born during the Great Depression showed signs of accelerated aging.
The results were determined by measuring the changes in the cells’ epigenome—the collection of chemical markers attached to DNA that determines when, where, and to what degree genes are expressed in each cell.
According to researcher’s analysis, they believe the pattern of markers that they discovered could be linked to higher rates of both chronic illness and death.
The period of the Great Depression that lasted from 1929 to 1939 led to the unemployment of about twenty-five percent of the U.S. workforce and was, therefore, a particularly stressful time for many.
Comparison of markers of aging during Great Depression
According to the research team, based on a comparison of eight hundred people who were born throughout the 1930s in various US states, the observable pattern of markers indicates that individuals’ cells looked older than they should have.
Although cells could have altered the epigenetic tags during early childhood or later in life, the results suggest that some sort of biological foundation was laid before birth for children of the Great Depression. This affected how they would age, epigenetically, later in life.
However, it’s unclear whether diet, stress, or other factors drove accelerated aging. Without being able to go back in time and tease apart those effects, it will be hard to pin down the biological mechanisms behind the signal, says Ainash Childebayeva, a biological anthropologist at the Max Plank Institute for Evolutionary Anthropology in Leipzig, Germany.
Nonetheless, “these kinds of studies are really important because they highlight how early development matters for health and disease outcomes later in life,” she says.
Hardships attributed to Great Depression shaped people’s health
The study capitalized on an accumulation of studies indicating that exposure to hardships such as stress and starvation during the earliest stages of development can shape human health for decades.
According to Lauren Schmitz, a co-author and economist at the University of Wisconsin–Madison, the findings indicate how social programs designed to help pregnant people could be a tool for fighting health disparities in children.
Patrick Allard, an environmental epigeneticist at the University of California, Los Angeles noted that the study is far from the first to link big historical events to changes in the epigenome. However, according to Allard, the fact that the signal appears in data collected from people in their seventies and eighties is “mind-blowing.”
Allard says, “It’s definitely something that will make its way into the textbooks.”
Epigenetic adjustments in relation to people’s DNA
Scientifically, during the earliest stages of development, an embryo is a packet of potential, containing genetic instructions to build the molecular components of the body.
However, with time, cells add and remove chemical modifiers known as epigenetic tags to their DNA. This shapes how those cells and their descendants execute instructions. The tags are influenced by a variety of factors, including people’s hormones, diet, and environment.
In 2008, researchers found that those conceived during a famine in the Netherlands at the end of the Second World War had different epigenetic markers compared to siblings born outside of this time frame. This is an indication that the alterations made during this key window can last a lifetime.
However, those born during the famine had higher rates of metabolic illness later in life. Hence, scientists suspected that exposure to malnutrition during early development permanently shaped how people processed food.
Ever since, a slew of animal studies has linked early exposure to pollutants, stress, and poor diet to a wide variety of epigenetic alterations that can shape everything from hair color to brain development.
Childebayeva, however, says that only a handful of studies have succeeded in finding these trends in humans—simply because subjecting people to harmful events such as famines to see how gene expression is shaped would be unethical.
Instead, scientists had to look back on major historical events to determine whether those events affected people’s biology later in life. Hence, the Great Depression and its aftermath provided scientists with such an opportunity.
People’s DNA in comparison to science and society
According to Schmitz, although both healthcare for pregnant women and economic theory has evolved since the 1930s, studies such as this one can shed light on modern societal issues.
Schmitz cited a scenario from earlier this year in which the US Supreme Court revoked the federal right to abortion.
He indicated that decades of research have shown that people who are denied abortions are more likely to experience financial hardship after an unwanted pregnancy than those with access to abortions.
“What we see from this study is that socioeconomic structural inequalities that make it difficult for women to access the care they need might have long-term consequences,” Schmitz says.
Commenting on childbirth related aspects, Schmitz says, “What we experience in those first nine months may affect us our entire lives.”
“I think we as a society can agree that experiencing a recession before you’re even born shouldn’t affect how long you live,” he emphasized.
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