Experience, beginning remarkably early in life, also influences how one responds to stressful environments. The amount of stress a female rat is exposed to during pregnancy influences the amount of glucocorticoids that cross the placenta and reach the fetus; that exposure can then alter the structure and function of that fetus’s hippocampus in adulthood. Separate a newborn rat from its mother for a sustained period and it will have increased levels of CRH as an adult. Seymour Levine, one of the giants of psychobiology, illustrates this point with a quotation from William Faulkner: “The past is not dead. It’s not even the past.” An understanding of the role of stress in psychiatric disorders offers much. It teaches us that a genetic legacy of anxiety or depression does not confer a life sentence on sufferers of these tragic diseases...Given that there is a continuum between the biology of these disorders and that of the “normal” aspects of emotion, these findings are not only pertinent to “them and their diseases” but to all of us in our everyday lives. Perhaps most important, such insight carries with it a social imperative: namely, that we find ways to heal a world in which so many people learn that they must always feel watchful and on guard or that they must always feel helpless.
Robert Sapolsky
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