Questions Related to Week 5 Readings:
- 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 do think this sensitive period is relevant in humans. Prenatal and perinatal exposures to toxins and illness often have a critical period of exposure in utero, and postnatal exposures likely have a sensitive period window as well. Skin-to-skin contact, breastfeeding, and cooing/speech are maternal behaviors that are considered to have important implications in an early period of life relative to later life. Forming attachments to the mother through kangaroo care and breastfeeding teach the child that their mother is not only a source of nourishment, but also a safe and secure adult that the infant can rely on for their needs. Research on the early cognitive development of infancy have cites infants’ attachments to their mothers often predict their attachment styles later in life (i.e., secure, avoidant, ambivalent/anxious, or disorganized). The closeness and position of breastfeeding also allows infants important time to learn and recognize facial expressions that may impact their future social interactions. Furthermore, speech has been documented to have a critical period, in which the more words a child hears early in life, the larger their vocabulary in toddlerhood, which undoubtedly has impact on their future scholastic achievement.
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 that Gruenewald’s findings are supplementary, rather than inconsistent with the Weaver findings. Just as certain behaviors and exposures may have a sensitive period window, the presence or absence of that exposure over a prolonged period of time—especially within the critical period—would understandably have a substantial impact on their growth and development. The cumulative effects of adversity sustained over a long period of time may even magnify the later disparities that would have been caused by a shorter period of adversity.
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 what this article is projecting is the progression of health disparities research from a survey of the singular causes of health disparities to now include how those individual causes interact with each other over the course of the lifetime. Research design has been important in controlling for other factors when trying to isolate a distinct feature that acts on its own to impact health outcomes. While this strategy has proved useful for identifying causes of disparities, intervention at the level of a singular factor will not result in substantial improvements unless all factors are considered and appropriately augmented as well. Study of the interactions of genetic, and environmental factors may prove useful to improve our interventions on a broader scale that incorporates how our early experiences influence our genetic makeup, so that we can prevent the genome-altering insults. As described by Hertzmann and Boyce, children may be biologically sensitive to context in general, but the environments that they grow up in—less vs. more privileged—may either work to protect them or worsen their outcomes.