Are we destroying our future? (children and genomics)

There is an ancient Chinese proverb or a curse depending on your perspective thatgoes something like, “May you live in interesting times”. And yes, we truly live in interesting times. The advances in Science, Technology and Medicine have been truly breathtaking and awe inspiring.

As we gambol merrily along our lives, we have to stop and think about the legacy that we are leaving our children in more ways than one. Are we giving our children a better standard of living? Are we leaving behind a better world? Are we leaving behind a happier world? As we look at these, the answers become a little more complex and less black and white. Yes, as we increase our income levels, they get to live in better quality buildings. Life gets more comfortable. There is access to increased medical care and better facilities. In most Asian countries as they rapidly modernize everything begins to look neater and cleaner. They never go hungry. They have access to appropriate educational facilities.

However lets look a little at the nitty gritty of the cleaner buildings and the other changes in the environment. Most of these changes are facilitated by the advent of modern technological changes. For one thing, every year there are 2000 new chemicals being introduced into the environment that were not there before. One estimate, is that from the time of our grandparents to date we have 100, 000 new chemicals that were not there before. If you ever go into a construction site, you would notice the use of glues, solvents and new chemicals that make the process of designing new buildings easy and the impact on biological systems traumatic. One of the most commonly used ingredients is formaldehyde. This was once primarily used to preserve dead animals It is a very toxic substance and is now used in 200 household items. Imagine what it does to the nerve and brain tissue of developing foetuses in the mother’s womb not to mention young children.

We are at the beginning of one of the most terrifying epidemics that is beginning to sweep the emerging first world economics ie. Asia, India and China. Its not SARs or even the swine flue. It’s the epidemic of Syndrome X. Syndrome X is the precursor to diabetes, heart disease and cancer. What is particularly pernicious about this is that the programming for this condition is in utero. The study of how genes are turned on or off by the environment (nutrition, diet, toxins and emotions) is called epigenetics. The implications of the epigenetic revolution are even more profound in light of recent evidence that epigenetic changes made in the parent generation can turn up not just one but several generations down the line, long after the original trigger for change has been removed.

In 2004 Michael Skinner, a geneticist at Washington State University, accidentally discovered an epigenetic effect in rats that lasts at least four generations. Skinner was studying how a commonly used agricultural fungicide, when introduced to pregnant mother rats, affected the development of the testes of fetal rats. He was not surprised to discover that male rats exposed to high doses of the chemical while in utero had lower sperm counts later in life. The surprise came when he tested the male rats in subsequent generations—the grandsons of the exposed mothers. Although the pesticide had not changed one letter of their DNA, these second-generation offspring also had low sperm counts. The same was true of the next generation (the great-grandsons) and the next.
Such results hint at a seemingly anti-Darwinian aspect of heredity. Through epigenetic alterations, our genomes retain something like a memory of the environmental signals received during the lifetimes of our parents, grandparents, great-grandparents, and perhaps even more distant ancestors. So far, the definitive studies have involved only rodents. But researchers are turning up evidence suggesting that epigenetic inheritance may be at work in humans as well.
In November 2005, Marcus Pembrey, a clinical geneticist at the Institute of Child Health in London, attended a conference at Duke University to present intriguing data drawn from two centuries of records on crop yields and food prices in an isolated town in northern Sweden. Pembrey and Swedish researcher Lars Olov Bygren noted that fluctuations in the towns’ food supply may have health effects spanning at least two generations. Grandfathers who lived their preteen years during times of plenty were more likely to have grandsons with diabetes—an ailment that doubled the grandsons’ risk of early death. Equally notable was that the effects were sex specific. A grandfather’s access to a plentiful food supply affected the mortality rates of his grandsons only, not those of his granddaughters, and a paternal grandmother’s experience of feast affected the mortality rates of her granddaughters, not her grandsons.

The studies by Pembrey and other epigenetics researchers suggest that our diet, behavior, and environmental surroundings today could have a far greater impact than imagined on the health of our distant descendants. “Our study has shown a new area of research that could potentially make a major contribution to public health and have a big impact on the way we view our responsibilities toward future generations,” Pembrey says.

The logic applies backward as well as forward: Some of the disease patterns prevalent today may have deep epigenetic roots. Pembrey and several other researchers, for instance, have wondered whether the current epidemic of obesity, commonly blamed on the excesses of the current generation, may partially reflect lifestyles adopted by our forebears two or more generations back.

Michael Meaney, who studies the impact of nurturing, likewise wonders what the implications of epigenetics are for social policy. He notes that early child-parent bonding is made more difficult by the effects of poverty, dislocation, and social strife. Those factors can certainly affect the cognitive development of the children directly involved. Might they also affect the development of future generations through epigenetic signaling?

Be well
Dr Sundardas