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?
I think this mechanism is relevant to humans, but the extent and degree to which it is directly applicable are probably much more complex.
If so, what behaviors are most analogous to “maternal licking and grooming”?
"There are stable individual differences in two forms of maternal behavior—LG and ABN—over the first week of lactation6–10. Such naturally occurring variations in maternal behavior are associated with the development of individual differences in behavioral and HPA responses to stress in the offspring. As adults, the offspring of ‘high-LG-ABN’ mothers are less fearful and show more modest HPA responses to stress than the offspring of ‘low-LG-ABN’ mothers."
If I had to speculate on an analogous behavior to "licking and grooming" for humans I would say providing physical (holding, carrying, playing) and verbal (singing, talking) comfort.
- 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.
"Analyses indicate higher AL as a function of greater SES adversity at each phase of, and cumulatively across, the life course. Associations were only moderately attenuated when accounting for a wide array of health status, behavioral and psychosocial factors. Findings suggest that SES adversity experience may cumulate across the life course to have a negative impact on multiple biological systems in adulthood"
Both findings seem to be consistent, but not completely connected. Early experiences in mammals with regard to maternal grooming influence adult responses to stress, and cumulative effects of SES adversity are detrimental to 'multiple biological systems' in adulthood. These narratives can easily be combined to show generational effects of SES adversity on maternal and child health.
- 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 gene*environment interactions could (and do) contribute to major disparities along racial/ ethnic, socioeconomic, or geographic dimensions. The complexity of these interactions is obviously very difficult to capture, especially considering the continuums of exposure and genetic susceptibility. Both of these systems are fairly dynamic, which adds to the difficulty in investigating G*E interactions.
"Essentially, all human disease is caused by the interaction between genetic and environmental factors" Modern epidemiology / Kenneth J. Rothman, Sander Greenland, and Timothy L. Lash. – 3rd ed.