Questions Related to Week 5 Readings:
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”?
I’m not sure we have any human mechanisms that function in such an extreme way as the example provided in the Weaver article. I think language development is probably a viable example of this mechanism, as some argue that there is a “window” (albeit a window that may last for many years) in which children need to develop certain linguist skills in order to have a greater chance of higher linguist capacity over their life course. That being said, I think that even something like language or human touch in infancy can be reversed within the right environment and attention. I can’t think of an example that is absolutely irreversible if not developed within a specific window (of course there may be biological/physiological attributes that I don’t know about given that I am not a provider).
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 think Gruenewald’s findings are consistent with Weaver’s – as they both demonstrate that environmental and epigenetic factors can directly influence health. I think Gruenewald’s article is an expansion of the Weaver piece and I think it provides a more appropriate and complex argument for a real-world environment. Both arguments make theoretical sense, but I find it more compelling to look at the effects of persistent exposure over an entire life course than at a single point/period in time.
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?
I think both genes and the environment are fundamental factors that influence developmental trajectories. Measuring environmental exposures is complicated, multidimensional, and effects individuals differently (which is hard to account for when studying population health). It’s important for the environmental portion of the analysis to focus on both the micro environment (one’s neighborhood, direct social contexts etc) and the macro structural environment that we may take for granted (social norms, taboos, structural violence etc). As an example of gene-by-environment, the authors talk about anti-social behavior. But behavior that is antisocial in one context may be acceptable in another environment. The environmental contextualization of the action shapes the very nature of it being antisocial to begin with. That makes the genetic component of the argument more difficult to understand. For an extreme example: cannibalism is considered in most of the world to be antisocial behavior. However we know that there are still places in the world practicing cannibalism is acceptable. In this example is the genetic predisposition for cannibalism itself, or for engaging in “antisocial behavior”? Also, I am not sure if the article was arguing that it was necessary for both genes and environment to be present in every situation - if that is there argument I don’t agree, as I believe there are circumstances in which environment or genes can have impact on health without the presence of the other.