A good dose of motherly love may be enough to alter our genetic code, leaving us less fearful and stressed out in later life, researchers have found.
The striking claim suggests that rather than our genetic blueprint being fixed before birth our bodies can tweak its biological book of instructions, allowing us to adapt more swiftly to a changing world, instead of waiting millions of years for evolution to take its course.
If the finding is confirmed it could lead to dramatic new insights into the effects of upbringing and life experiences on a vast range of medical conditions, including obesity, diabetes and depression.
The discovery follows tests in rats in which newborns were raised by mothers who spent different amounts of time licking and grooming their young.
Researchers have long known that animals brought up with a lot of maternal care are less easily frightened and more adventurous. The tests, by a team of geneticists at McGill University in Montreal, showed that motherly care had its calming effect by altering the expression of a gene that governs the brain’s response to stress.
The genetic tweak leads to more stress receptors growing in part of the brain called the hippocampus, which together act to dampen down the body’s reaction to stressful situations. Later tests suggested the genetic changes were long lasting and were even passed to future generations.
The study, published in the Journal of Neuroscience this week, is the latest in the field of epigenetics, which describes how each of the genes we inherit is tweaked by the molecular equivalent of a volume control, with some being silenced and others being flicked to overdrive.
Moshe Szyf, a co-author of the paper, said the changes were, in effect, a fast-track way for the body to fine-tune itself to its surroundings. ”The fact that the social environment can change genes in a very stable manner has immense implications if it’s true for humans. By moving people from one environment to another you might completely reprogramme their genome and cause either positive or negative effects on them later in life.”
Szyf added that anything that caused a regular, long-term release of chemicals in the brain, from extended bingeing to a sustained bout of sexual activity, might lead to epigenetic changes. Previous studies have hinted that starvation in malnourished babies may lead to similar changes that alter their metabolism, predisposing them to obesity in later life.
The changes witnessed in the rat tests make sense, says Rosalind John, a geneticist at Cardiff University. A mother raising its young in a dangerous environment may devote less time to grooming them, so the young will become more fearful — a life-saving trait if there is a grave threat from predators. — Â