1. Weaver et al propose that among rats, maternal behavior towards newborn pups influences their cortisol response to stress via epigenetic mechanisms that change the expression of glucocorticoid receptor gene for the rest of the pup’s life. They argue that because epigenetic patterns are established at specific developmental periods, there is extreme time sensitivity to when the pup is exposed to particular maternal behaviors (licking and grooming, in this case), and maternal behavior before or after that sensitive period window is not as important. Do you think this mechanism is relevant in humans? If so, what behaviors are most analogous to “maternal licking and grooming”?
Yes, I do think that this mechanism of maternal behavior can be applied in humans as well. There evidence in the literature indicating that this mechanism is susceptible to changes in nutrients and food to which the infant is exposed to in the prenatal and early infant period (Remely et al 2015). For example, a baby born in Sierra Leone and exposed to eating less caloric foods in early childhood, and if then, if this child migrated to the US and then exposed to high caloric diet as he grows to adulthood, weaver is saying that this child may likely not be obese and hence develop diabetes. However, I do think this child if exposed to high caloric diet which is the environmental stress might be obese and could develop secondary diabetes. Confirming that environmental stress has a play in the outcomes if an individual in later life.
Remely, M., Stefanska, B., Lovrecic, L., Magnet, U., & Haslberger, A. G. (2015). Nutriepigenomics: The role of nutrition in epigenetic control of human diseases. Current Opinion in Clinical Nutrition and Metabolic Care, 18(4), 328-333.
2. Gruenewald, in contrast, emphasize the cumulative effects of SES adversity on a multi-system
allostatic load measure. Do you think that the Gruenewald findings are consistent, inconsistent, or unrelated to the Weaver findings? Explain.
I do think that the Gruenewald and weaver findings are a bit different even though their conclusions tend to agree with each other: both studies found that the determinants that occur early on in an individual’s life have an effect on their health in adulthood While Weaver focus is on the positive determinants of health (i.e. maternal grooming in influencing stress in offspring), Gruenewald focused at models of negative determinants of health (i.e. the effect of SES adversity on allostatic load). Weaver focused on the mechanism by which this may occur, where there is a critical period during which these maternal behaviors influence the pattern in the offspring (very early on after birth), which will continue into adulthood and affects how an individual respond to stress. Similarly, Gruenewald investigated a life course approach, whereby those with greater SES adversity across the life course (childhood and adulthood) have greater negative effect on the biological functioning in later adulthood.
3. Hertzmann and Boyce argue that “it is not genes or environment, nor is it genes and environment, but rather it is gene-by-environment interactions that influence developmental trajectories.” To what extent do you think that GxE interactions can contribute to major disparities along racial/ethnic, socioeconomic, or geographic dimensions?
Yes, I agree with Hertzmann and Boyce, that the gene-by-environment interaction is the more important factor in influencing developmental trajectories. All individual is born inherently with specific physiological qualities which are influenced by the environment they are exposed to. The environment plays an important role in shaping people as they develop their personalities and lifestyles. An interaction between the environment and an individual's health status can be directly linked, for example if you grow in an environment where smoking is common of in a household where the mother and father smokes you will more likely become a smoker as you grow up. And thus, increase the risk of developing hypertension.