Here is a quote from Research News, a magazine distributed to researchers in Alberta. The article was featured in their Spring 2008 edition. The full article is included below.
“Dr. Michael Meaney’s research turns the old nature-versus-nurture debate on its head. His work shows that a mother’s touch can trigger genes that shape her child’s stress response.”
Nature versus nurture.
It’s an age-old debate about the relative roles played by our inherited characteristics and our environment in determining who we become. The controversy over which factor is dominant has raged on for centuries: To what extent are we preprogrammed by our DNA, and to what extent are we shaped by our experiences and the world around us? Psychologist Donald Hebb called it a false question-akin to asking whether length or width contributes more to the area of a rectangle. Now an emerging field called epigenetics is providing new evidence that nature and nurture are, in fact, inextricably linked, and information on how they work together.
Epigenetics is the study of changes in the activity of the gene that occur without any changes in the structure of its DNA. For example, factors such as maternal stress and nutrition and the infant’s own diet (nurture) have been shown to change gene function without altering the DNA sequence (nature) in any way. Epigenetics can help explain how identical twins, who have exactly the same genes, may have different experiences of disease: one twin may develop cancer or schizophrenia while the other does not.
Dr. Michael Meaney, the winner of AHFMR’s inaugural Lougheed Prize, is a leading researcher in the field of epigenetics. He was one of the first researchers to identify the importance of a mother’s care in the development of her child, as well as the child’s ability to cope with stress later in life.
It all started with Dr. Meaney’s observations of female rats and their nurturing behaviour toward their offspring – in other words, how frequently these rat mothers lick their pups.
He discovered that the level of care a rat mother gives her pup changes the chemistry of the DNA in certain genes involved in the offspring’s stress response. “The interaction causes these genes to become either more or less active,” explains Dr. Meaney. “Genes can’t function independently of their environment. So every aspect of our lives is a constant function of the ‘dialogue’ between environmental signals and the genome.” This is epigenetics.
Dr. Meaney and his team found that frequent licking had an immediate impact on the growth of the rat pups. It enhanced the activity of growth hormones and decreased the release of glucocorticoids -compounds involved in the stress response. “For us, the holy grail was to identify the path that was being altered by this licking behaviour,” he says. “We identified the one small region on the gene that responds to maternal care and directs changes in the brain cells.”
Since these observations in rats lead us to wonder-quite naturally-about similar effects in people, Dr. Meaney is now embarking on studies which will look at child development in humans. He points out that the weight of a child at birth is a remarkably reliable predictor of the health of that child throughout life. A high birthweight predicts good health; a low birthweight predicts poor health. Factors that contribute to low birthweight include high levels of maternal stress, poor maternal nutrition, and tobacco and alcohol consumption by the mother. But if the mother’s glucocorticoid levels are high, they can contribute to low birthweight too. Glucocorticoids inhibit growth of the fetus, and can affect the development of the brain by reducing the size of the hippocampus -the part of the brain that affects attention and the ability to focus. Yet, as he points out, many babies with a low birthweight do very well later in life. So postnatal care must be one of the factors that are capable of reversing these early effects.
“The bottom line seems to be that parental care can have an even bigger impact than we ever dreamed on our children’s lives,” says Dr. Meaney. “We’re just starting to learn what that means”
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