Why are we fat? Republicans, Democrats disagree


If the recent elections have taught us anything, it’s that Democrats and Republicans are so deeply divided that one might reasonably argue that the system has broken down, with folks of great wealth fueling the divisions for their own ends.

So how deeply divided are the two parties?

Well, they can’t even agree on what makes folks fat.

It’s that old nature/nurture divide that lurks beneath so much of political divisiveness, with the Republicans arguing that Calvinism, with its doctrine of predestination, rules at the bathroom scales, while Democrats argue that it’s something fueled by the environment.

From the University of Kansas:

People’s political leanings and their own weight shape opinions on obesity-related public policies, according to a new study by two University of Kansas researchers.

Actually, Republicans — no matter how much they weigh —  believe eating and lifestyle habits cause obesity, the research found.

But among Democrats there is more of a dividing line, said Mark Joslyn, professor of political science. Those who identify themselves as overweight are more likely to believe genetic factors cause obesity.

“Self-reported overweight people were significantly more likely to believe obesity is caused by genetics than normal weight people,” Joslyn said. “The belief that obesity is due to genetics tends to remove blame. Obesity is not a choice, some would argue, but rather people are simply genetically wired to be obese. In this way, overweight people are motivated to believe in the genetics-obesity link. We found normal weight people were not so motivated.”

Joslyn and Don Haider-Markel, chair and professor of the Department of Political Science, published their findings [$36 to read] recently in the journal American Politics Research.

The research could have important implications for policymakers, especially at the local and state levels that tend to focus on public health interventions, either through appealing to healthy lifestyles by constructing biking and walking paths to encourage exercise or by passing stricter regulations on food and drinks, such as demanding publication of calorie counts and levying taxes on soft drinks.

Former New York City Mayor — and billionaire — Michael Bloomberg has donated millions of dollars to fund pro-soda tax initiatives in major cities. Berkeley, California, and Philadelphia are among those that have passed them in recent years. Obesity rates have risen recently in the United States, as the U.S. Centers for Disease Control and Prevention reported in 2015 that 71 percent of adults were overweight and more than 17 percent of youths were obese.

Still, most Americans oppose bans on large-size drinks and higher soda taxes, Joslyn said, which is likely a disparity between the perception of the problem and support for government intervention. Those who have argued against soda taxes, for example, often refer to a “nanny state,” blaming government intervention when they perceive personal choice is causing the problem.

For policymakers, as obesity rates continue to climb and the debate surrounding how to make people healthier continues, the genetic attribution as a cause may continue to rise as well, which could influence people’s opposition to certain practices.

“To the extent that genetic attributions increase in popularity, stronger opposition to discriminatory hiring practices by weight can be expected,” Joslyn said.

Also, it’s likely the issue remains politicized because most Republicans are inclined to support individual blame for obesity and not supportive of government regulations.

Finally, while the soda taxes have gained much attention, most government action recently does seem to be directed toward changing people’s individual behavior, such as developing public spaces to encourage fitness and ways to discourage unhealthy eating habits, like publication of calorie counts.

“If obesity persists in the face of such initiatives, blame and discrimination of obese people is likely to continue,” Joslyn said. “On the other hand, if governments treat obesity similar to diseases that afflict the population, as circumstances beyond the control of individuals, then individual blame and discrimination may diminish.”

Program notes

The genome dynamically interacts with the environment as chemical switches that regulate gene expression receive cues from stress, diet, behavior, toxins and other factors. Epigenetics is the study of these reactions and the factors that influence them.

So what’s it all about?

From Scientific American:

In a study published in late 2011 in Nature, Stanford University geneticist Anne Brunet and colleagues described a series of experiments that caused nematodes raised under the same environmental conditions to experience dramatically different lifespans. Some individuals were exceptionally long-lived, and their descendants, through three generations, also enjoyed long lives. Clearly, the longevity advantage was inherited. And yet, the worms, both short- and long-lived, were genetically identical.

This type of finding—an inherited difference that cannot be explained by variations in genes themselves—has become increasingly common, in part because scientists now know that genes are not the only authors of inheritance. There are ghostwriters, too. At first glance, these scribes seem quite ordinary—methyl, acetyl, and phosphoryl groups, clinging to proteins associated with DNA, or sometimes even to DNA itself, looking like freeloaders at best. Their form is far from the elegant tendrils of DNA that make up genes, and they are fleeting, in a sense, erasable, very unlike genes, which have been passed down through generations for millions of years. But they do lurk, and silently, they exert their power, modifying DNA and controlling genes, influencing the chaos of nucleic and amino acids. And it is for this reason that many scientists consider the discovery of these entities in the late 20th century as a turning point in our understanding of heredity, as possibly one of the greatest revolutions in modern biology—the rise of epigenetics.

And here’s a helpful graphic from a 2010 report from the National Scientific Council on the Developing Child and Harvard University’s Center on the Developing Child notes:

More from the report:

Research in both animals and humans shows that some epigenetic changes that occur in the fetus during pregnancy can be passed on to later generations, affecting the health and welfare of children, grandchildren, and their descendants. For example, turning on genes that increase cell growth, while at the same time switching off genes that suppress cell growth, has been shown to cause cancer. Repetitive, highly stressful experiences can cause epigenetic changes that damage the systems that manage one’s response to adversity later in life. On the other hand, supportive environments and rich learning experiences generate positive epigenetic signatures that activate genetic potential. In this second case, the stimulation that occurs in the brain through active use of learning and memory circuits can result in epigenetic changes that establish a foundation for more effective learning capacities in the future.

As we get older, new experiences can continue to change our epigenome. However, science tells us that the chemical signatures imprinted on our genes during fetal and infant development can have significant influences on brain architecture that last a lifetime. Stated simply, the discovery of the epigenome provides an explanation, at the molecular level, for why and how early positive and negative experiences can have lifelong impacts.

But the role payed by epigentics goes much deeper

In fact, epigenetic changes themselves may be inherited, and pone of the most telling examples comes from the darkest parts of our history.

As  Siddhartha Mukherjee noted in the New Yorker in May:

The most suggestive evidence for such transgenerational transmission may come from a macabre human experiment. In September, 1944, amid the most vengeful phase of the Second World War, German troops occupying the Netherlands banned the export of food and coal to its northern parts. Acute famine followed, called the Hongerwinter—the hunger winter. Tens of thousands of men, women, and children died of malnourishment; millions suffered it and survived. Not surprisingly, the children who endured the Hongerwinter experienced chronic health issues. In the nineteen-eighties, however, a curious pattern emerged: when the children born to women who were pregnant during the famine grew up, they had higher rates of morbidity as well—including obesity, diabetes, and mental illness. (Malnourishment in utero can cause the body to sequester higher amounts of fat in order to protect itself from caloric loss.) Methylation alterations were also seen in regions of their DNA associated with growth and development. But the oddest result didn’t emerge for another generation. A decade ago, when the grandchildren of men and women exposed to the famine were studied, they, too, were reported to have had higher rates of illness. (These findings have been challenged, and research into this cohort continues.) “Genes cannot change in an entire population in just two generations,” [Rockefeller University molecular biologist David] Allis said. “But some memory of metabolic stress could have become heritable.”

And on other side of the same coin, epigenetic changes affected behavior and much more have also been noted in the children and grandchildren of Holocaust survivors, as the Guardian reported on 21 August 2015:

Genetic changes stemming from the trauma suffered by Holocaust survivors are capable of being passed on to their children, the clearest sign yet that one person’s life experience can affect subsequent generations.

The conclusion from a research team at New York’s Mount Sinai hospital led by Rachel Yehuda stems from the genetic study [open access] of 32 Jewish men and women who had either been interned in a Nazi concentration camp, witnessed or experienced torture or who had had to hide during the second world war.

They also analysed the genes of their children, who are known to have increased likelihood of stress disorders, and compared the results with Jewish families who were living outside of Europe during the war. “The gene changes in the children could only be attributed to Holocaust exposure in the parents,” said Yehuda.

Her team’s work is the clearest example in humans of the transmission of trauma to a child via what is called “epigenetic inheritance” — the idea that environmental influences such as smoking, diet and stress can affect the genes of your children and possibly even grandchildren.

So the attitudes of both Democrats and Republicans on the obesity question are each half right.

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