Epigenetics: How Environment Changes Your Biology

Epigenetics is the science of living DNA, charting the chemical pathways that spur DNA into action by turning genes on and off. This rapidly advancing field has overturned traditional ideas about heredity, revealing that both behavior and the environment can affect the way our genes work. Adding a new twist to the nature-versus-nurture debate, epigenetics researchers have discovered that:

• We Inherit More Than We Suspect. Changes that affect the activity of DNA can be passed from parents to children.
• Epigenetics Works Quickly. Twenty minutes of exercise or just one meal can transform how your genes function.
• Pollution Gums Up Genetic Machinery. Pollution from a wide range of chemicals has a long-lasting effect on gene expression.

While the Human Genome Project of the early 2000s was hailed as the key to understanding human heredity and disease, this historic effort was just the beginning. It has taken epigenetics to fill in the picture, explaining how the fixed code of our genome is implemented in countless cellular activities. The same goes for the genomes of every living thing on Earth; epigenetics calls the shots.

Epigenetics: How Environment Changes Your Biology covers this vital science in 12 in-depth, half-hour lectures, presented by noted British epigeneticist, physician, and science communicator Dr. Charlotte Mykura.

Lively and authoritative, Dr. Mykura explains how epigenetics is ubiquitous, influenced by activities like diet and lifestyle. For example, aging is largely an epigenetic phenomenon. So is our susceptibility to many diseases, as well as our body’s ability to fight infection. You learn how epigenetics governs the X and Y chromosomes, the miraculous process of building an embryo, and the transmission of environmental experience between generations. And you investigate how epigenetics evolved in the first place and where the epigenetic universe might take us next, especially in the realm of medicine.

Enter the Epigenetic Jungle

Dr. Mykura begins with something we all learned in middle school: that the double helix of DNA is ingeniously organized to encode the complete genetic blueprint for an organism—a masterplan that is present in practically all cells. Skin cells, nerve cells, bone cells, muscle cells, and female egg cells, among others, all have the entire plan. But that raises the question: How does DNA know what to do, where to do it, and when? After all, a foot doesn’t grow out of your head, even though the instructions are right there in the cells of your scalp—along with information for every other body part you have.

Epigenetics: How Environment Changes Your Biology clears up this mystery and more. It turns out that the graceful spiral-staircase structure of DNA familiar in introductory textbooks is not what the molecule looks like in action. That’s why this course focuses on living DNA—folded, twisted, constantly shapeshifting, and performing biological wonders thanks to epigenetics.

Dr. Mykura often refers to the epigenetic “jungle,” which includes your:

• Chromosomes and Genes. In humans, DNA is divided into 46 chromosomes, comprising some 20,000 genes, which are segments of DNA that code for proteins—the workhorses of cellular metabolism.
• Regulatory DNA. Between the genes are long stretches of non-coding DNA. Once called “junk DNA” because it was thought to be useless, scientists now suspect it plays a crucial role in epigenesis.
• Methyl Groups and Histones. These are the masterminds of epigenetics, binding to DNA, transforming its shape, switching genes on and off, and performing other important functions.

“A chromosome will spend most of its life looking something a bit like a hairball,” says Dr. Mykura, “with each of your 46 chromosomes forming its own hair ball clump.” But there’s method in that fuzzy mess, she explains, as a host of epigenetic molecules move into place to control the compaction and expression of different genes. In her explanation of the epigenetic jungle, Dr. Mykura is like an explorer making sense of the intricate ecology of the rainforest.

Discover a New World

Unlike some scientific revolutions, epigenetics has developed slowly, with mounting evidence pointing at extraordinary conclusions. An early hint came in the aftermath of the famine that gripped Nazi-occupied Holland during the last winter of World War II. One would expect health repercussions in the children born to malnourished mothers who survived the famine. But the health effects have persisted in subsequent generations, as if these descendants inherited something borne from their ancestors’ experience. Incredibly, these offspring appear to have inherited traits governed by epigenetic markers, not changes in their genome. This suggests there might be some truth to the long-discredited idea of inheritance of acquired characteristics, promoted by 19th-century French biologist Jean-Baptiste Lamarck. Dr. Mykura presents and evaluates the evidence for this startling hypothesis.

She opens your eyes in other ways, too, exploring the epigenetics of:

• Diet. The worldwide obesity epidemic is happening far too fast to be explained by genetic changes. Epigenetic imprinting is the likely culprit, caused by poor diet and capable of being inherited.
• Smoking. Tobacco smoke bathes lung tissue in over 60 cancer-causing compounds, overwhelming DNA damage-repair enzymes. With our epigenomes stunned by cigarette smoke, we’re vulnerable to cancer.
• Cannabis. The increased use of cannabis has seen a parallel growth in mental illnesses like schizophrenia, partly due to the epigenetic effects of cannabinoid compounds that behave like neurotransmitters.

The idea that specific foods and chemicals pose a health risk is hardly new. But Dr. Mykura zeroes in on exactly how harm is done at the cellular level and, alarmingly, how that damage can alter the epigenetic modifications that are passed on to our offspring. On a more positive note, she points out the beneficial epigenetic alterations that come from regular exercise, a plant-dominated diet, and periodic fasting, among other lifestyle choices.

Fascinated with biology since she was a child, Dr. Mykura pursued that interest through medical school and a research doctorate. In her decades of immersion in the life sciences, epigenetics has been a revelation to her. “Epigenetics is like discovering a whole world you never even knew existed,” she marvels. “Whenever you really look at the hive of activity that brings our DNA to life, what you find is epigenetics.” In this course, you, too, will be impressed by this powerful new science.