Among the several recent developments in biomedical research that are beinghyped as revolutionary, the science of epigenetics has inspired the boldest claims.
Epigenetics is “at the epicenter of modern medicine,” according to one piece in the Journal of the American Medical Association. Epigenetic diets will help us be healthier. New epigenetic drugs will help us fight common diseases and disorders ranging from cancer to drug addition. For social scientists, epigenetics offers a biological basis for the lasting effects of childhood abuse, socioeconomic disadvantage, and racial health disparities.
There are at least a half-dozen popular books devoted to epigenetics, explaining how the field is “rewriting our understanding of genetics” and even claiming that we can make ourselves healthier by controlling our genes with our thoughts. In what appears to be a validation of these broad claims, the National Institutes of Health has sponsored a $240 million project devoted to it.
This sounds like an important development, but what exactly is epigenetics? The answer is a bit fuzzy because this is a field that, as one commentary aptly put it, “thrives in the ambiguity of its own definition.” Scientists are often careless in how they apply the term. But much of the current excitement over the science of epigenetics has to do with a set of molecular processes that control our genes. These control processes mark up our genome with chemical tags that identify which parts of our DNA are active and which are not. These chemical marks can change during the progression of a disease, or, in some cases, in response to stress, diet, or other sorts of environmental changes. Thanks to recently developed technologies, we can detect these marks much more comprehensively than ever before, which means that researchers can now observe how a genome changes over time in response to environmental changes, social stresses, and disease.
The idea that our DNA, rather than being an immutable fact of our biology, is actually responsive to changes in our health and our environment is what makes people so enthusiastic about epigenetics. According to a popular metaphor, our genes themselves may be written in ink, but they’re marked up in pencil—which can be erased and re-done. By developing drugs or treatments that modify these pencil marks, so the thinking goes, we can escape the limits imposed by our genes, which can’t be changed. Cancer, for example, is caused by genetic mutations that can’t be undone, but it is also characterized by abnormal epigenetic marks, which can potentially be reversed. Researchers have struggled for years, with little success, to fix our genetic print by repairing mutations with gene therapy. But in some cases we may not need to repair mutations if we can re-work the epigenetic pencil marks instead.
If this idea is right, the impact could be tremendous, because researchers have found epigenetic changes associated with almost everything. Distinct patterns of epigenetic marks are found not only in cancer, but most other common diseases as well, including psychiatric ones like depression and addiction. Differences in epigenetic marks are being linked with differences in socioeconomic status, andone study found epigenetic changes in suicide victims who had suffered childhood abuse. Even more worrying is the idea (still largely speculative) that epigenetic marks can be passed on from one generation to the next, meaning that parents may pass on the effects of their poor health choices, diet, or social environment to their children.
The potentially broad impact of epigenetics has drawn the attention of social scientists, who are not usually worried about the details of molecular biology. A team of bioethicists has called epigenetics one of the most “legally and ethically significant cutting-edge subjects of scientific discovery” because “a large range of environmental, dietary, behavioral, and medical experiences can significantly affect the future development and health of an individual and their offspring.”
This sounds both liberating and terrifying at the same time: Our destinies are not fixed by our genes, and yet much of what we do and experience could have a profound effect on the biological make-up of ourselves and our children. But the hype has outrun the science. As one group wrote last year, “scientific hyperbole rarely generates the level of professional and personal prescriptions for health behavior that we are now seeing in epigenetics.” Many of the boldest claims being made about the relationship between epigenetics, health, and our environment are based only on evidence from animal studies, and thus are, at best, premature. In fact, much of the recent research in epigenetics hasn’t turned up anything fundamentally new.
Scientists have long been aware that our genes aren’t chiseled in stone—they are in a constant dialogue with our environment. The epigenetic marking up of our DNA, discovered decades ago, is a key part of how that dialogue takes place. And while these marks are an important feature of our biology, the biggest flaw in many of the claims being made about epigenetics is that they confuse cause with effect.
Epigenetic marks are a consequence of changes in the activity of our genes in response to our health, our environment, and our social experiences, but they arenot the underlying cause of those changes. There is no reason to believe that drugs, treatments, or health advice that target these DNA markings will be unusually effective compared to therapies that aren’t specifically epigenetic.
While epigenetics is rife with hype, there is at least one advantage to all of the attention this field is getting: People are recognizing just how profoundly our physical and social environment can affect our biology.
The molecular details being discovered in the latest epigenetic studies are largely irrelevant. What matters is that our well-being isn’t simply a simple sum of the effects of our genes and the impact of our environment; the two are deeply intertwined. For this reason, social scientists are right to latch on to what would otherwise be a relatively obscure field of biology.
A pair of anthropologists at Northwestern University summed up the issue well in a study of racial health disparities, writing that “in the current polarized discourse over health inequality, some interpret the inability of adult socioeconomic and behavioral factors to account for racial disparities in disease burden as evidence for underlying genetic differences.” By attributing these racial disparities to genetic differences, we “ignore evidence that social factors can have durable life-course and transgenerational effects on health.” The latest developments in epigenetics aren’t revolutionizing biology. But they are helping us accept the role that biology plays in our lives and our society.