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Our Epigenome and What it Means for our Past, Present, and Future

by Riley Ramsey for ENGL 30400 Advanced English Composition at Purdue University

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Epigenetics is an emerging field of study that has revolutionized our understanding of how genes and the environment interact to influence our health and well-being. While the science behind epigenetics can be complex, there are several key concepts that people outside the world of biology should know.

First and foremost, epigenetics are the study of how genes are turned on and off, and how this process can be influenced by environmental factors individuals endure or our ancestors experienced. While we inherit our genes from our parents, grandparents, etc, it is the way these genes are expressed that ultimately determines our physical traits and susceptibility to certain diseases. Reading this, however, with a background in evolution, you may ask yourself – aren’t all environmental pressures experienced by our ancestors what drives genetic inheritance? How is this different?

It is the scope of which these epigenetic markers are placed (or, removed) that makes them unique – it can happen at the individual level (I.E., a great, great, great grandmother) and individual experiences (i.e., a great, great, great grandmother lived through a famine and survived). This concept completely contradicts a totem of foundational biology education – individuals cannot change their genes, and thus conscience decisions cannot be inherited. A prime example coming from my own Bio 101 professor’s notes; hitting the gym does not cultivate a ripped baby. But we’re learning that (albeit not that specific example) these methyl groups can be transmitted through meiosis, or sexual cell division, or, the cells that become new people. Slavich and Cole say it best – “[Epigenetic research] sheds new light on the evolution of the human genome and challenges the fundamental belief that our molecular makeup is relatively stable and impermeable to social-environmental influence.” Our very chemistry is shaped by our manufactured societal inequities. An example study demonstrated that lower socioeconomic status can lead to changes in DNA methylation patterns that increase the risk of cardiovascular disease and inflammation. (McGuinness, et al., 2012)

One important mechanism of epigenetics is DNA methylation, which is adding a chemical group to the DNA molecule that can prevent certain genes from being expressed. Imagine your genome as the teeth of a zipper, and the enzyme responsible for gene expression as the zipper. If one tooth were to become crooked or become bulbous, that zipper would not become undone. From an undone zipper, more complex systems have the space necessary to do some major construction – but without an open zipper, this work cannot be done.

Another key aspect of epigenetics is histone modification, which refers to chemical changes that occur to the proteins around which DNA is coiled, known as histones. Histones help regulate gene expression by controlling how tightly the DNA is wound, and modifications to histones can influence this process. Acetylation of histones can loosen the DNA, making it more accessible for gene expression, while methylation can have the opposite effect, making the DNA more tightly coiled and less accessible as previously mentioned. Studies have shown that changes in histone modifications are associated with various health outcomes, such as cancer, autoimmune diseases, and neurological disorders (Kouzarides, 2007).

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Perhaps one of the most exciting aspects of epigenetics is the potential for epigenetic changes to be reversed or modified through lifestyle changes. For example, studies have shown that regular exercise and a healthy diet can lead to changes in DNA methylation patterns that promote better health and longevity (Hibler, E. 2019). Control over our very biology – amazing, isn’t it? But taking a step back and thinking, how attainable can this control really be? Barriers to healthy lifestyles that exist are nearly impenetrable to the vast majority of the world due to the very socio-economic stress that produced the genomic markers in the first place. 

While the science of epigenetics is still in its early stages, it is clear that our environment plays a crucial role in shaping our genetic destiny. By understanding the mechanisms of epigenetics and making positive lifestyle choices, we can take control of our health and wellbeing in a whole new way – systemically. 

References:

Fraga, M. F., Esteller, M., & Paz, M. F. (2005). Epigenetics and aging: the targets and the marks. Trends in genetics : TIG, 21(11), 607–613. https://doi.org/10.1016/j.tig.2005.09.005 

Hibler, E., Huang, L., Andrade, J. et al. Impact of a diet and activity health promotion intervention on regional patterns of DNA methylation. Clin Epigenet 11, 133 (2019). https://doi.org/10.1186/s13148-019-0707-0 

Kouzarides, T. (2007). Chromatin modifications and their function. Cell, 128(4), 693–705. https://doi.org/10.1016/j.cell.2007.02.005 

Liu, D., et al. (1997). Maternal care, hippocampal glucocorticoid receptors, and hypothalamic-pituitary-adrenal responses to stress. Science (New York, N.Y.), 277(5332), 1659–1662. https://doi.org/10.1126/science.277.5332.1659 

McGuinness, D., et al. (2012). Socio-economic status is associated with epigenetic differences in the PSOBID cohort. International Journal of Epidemiology, 41(1), 151–160. https://doi.org/10.1093/ije/dyr215 

Mulligan, C. J. (2016). Early Environments, Stress, and the Epigenetics of Human Health. Annual Review of Anthropology, 45, 233–249. http://www.jstor.org/stable/24811564 

Nada Borghol, Matthew Suderman, Wendy McArdle, Ariane Racine, Michael Hallett, Marcus Pembrey, Clyde Hertzman, Chris Power, Moshe Szyf, Associations with early-life socio-economic position in adult DNA methylation, International Journal of Epidemiology, Volume 41, Issue 1, February 2012, Pages 62–74, https://doi.org/10.1093/ije/dyr147 

Slavich, G. M., & Cole, S. W. (2013). The Emerging Field of Human Social Genomics. Clinical psychological science : a journal of the Association for Psychological Science, 1(3), 331–348. https://doi.org/10.1177/2167702613478594 

Thayer, Z. M. and Non., A "Anthropology Meets Epigenetics: Current and Future Directions." American Journal of Human Biology, vol. 28, no. 4, 2016, pp. 518-530. 

Figure 1 - sunka_art/Shutterstock, via https://newscenter.lbl.gov/2020/10/05/genes-environment-health/ 

Figure 2 – Illustration by AXS Biomedical Animation Studio via https://www.scientificamerican.com/article/epigenetics-inheritance-acquired-characteristics/ 

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