Epigenetics revamps our understanding of human development from embryo to adult, and even how our species got to be here. I spoke with one of the foremost researchers in the field, Dr. Moshe Szyf, at McGill University’s storied medical school. “Evolutionary theory is a difficult one to change because it became almost religion, a religion of science,” he said. “And any questioning of it seems to be a heretical question of the whole system, which obviously it isn’t. Epigenetics doesn’t deny evolution. Epigenetics is part of evolution, but it demands a new look at how evolution works.” The new biology improves upon the standard Darwinian view of spontaneous mutations and random selection as the motors of species adaptations; it demonstrates that circumstances themselves can shape how genes adjust to the environment.
Said another way, our lives are what happens when life acts upon life.
Dr. Szyf and his team in Montreal performed one of the most cited epigenetic studies, with major implications for how we view development, behavior, and health. Working with laboratory rats, they examined the effect of the mother’s interactions with the infant in the first days after birth on how the offspring, for the rest of their lives, respond to stress—whether appropriately and confidently or with anxiety and over-reactivity. The focus was the HA axis, the stress-regulating feedback loop between the hypothalamus and the pituitary and adrenal glands. In particular, the researchers looked at receptor molecules in the brain whose task it is to modulate stress, which is to say, to ensure the appropriate behavior when stress is present. Creatures with poorly self-regulated stress reactions will be more anxious, less capable of confronting ordinary environmental challenges, and overstressed even under normal circumstances.
The study showed the quality of early maternal care to have a causal impact on the offspring’s brains’ biochemical capacity to respond to stress in a healthy way into adulthood. Key epigenetic markers—the ways certain genes expressed themselves—were different in the brains of rats who had received either more, or less, nurturing contact from their mothers. Strikingly, the offspring in turn passed on to their own infants the type of mothering they had been given. Szyf and his colleagues have also shown that the quality of maternal care affects the receptor activity for estrogen—a key female hormone—in daughters, with ramifications for mothering patterns down the generations. Through ingenious manipulation of the rat population studied inconceivable in human research—both the physiological and behavioral effects of early nurturing patterns were found to be nongenetic: that is, not transmitted through the so-called genetic code, which remained unchanged. Rather, they were epigenetic—in other words, determined by how the various kinds of maternal nurturing influenced gene activity in the offspring’s brain. (The specific maternal behavior tracked by these researchers was how “lovingly” the moms “groomed,” or licked, their infants.)
Gabor Maté and Daniel Maté – The Myth of Normal: Trauma, Illness & Healing in a Toxic Culture p.62
The Sea Is Not Full 