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Biological Memories and Epigenetics

About the Authors

Zaneta M. Thayer is a biological anthropologist pursuing her doctorate at Northwestern University, and she has a B.A. in anthropology and biology from Dartmouth College. Thayer is interested in how the environment affects patterns of human biological variation, particularly during early development. Her primary research has been on the epigenetic effects seen in fetal development. One of her long term goals is to unite developmental biology with the Modern Synthesis as an expansion of modern evolutionary theory.

https://sites.google.com/a/u.northwestern.edu/zaneta-thayer/

Chris Kuzawa, a Professor  at Northwestern University, is a biological anthropologist with a background in epidemiology. He received both his PhD and his MsPH (Masters of Science in Public Health) from Emory in 2001.  He focuses on developmental biology and the diseases and effects that early postnatal environments have on humans. The premise of this research is that what a mother eats during pregnancy, her access to adequate prenatal care, or her stress level, may permanently alter offspring biology in a fashion that influences risk for the most common causes of adult morbidity and mortality, including hypertension, diabetes, and heart attacks. He focuses on the term "Developmental Plasticity", which is the sensitivity of a developing body to its environment.

His current projects are on developmental influences on obesity and male reproductive ecology in the Philippines and Inter-generational influences on health in the United States

http://www.anthropology.northwestern.edu/people/faculty/kuzawa.html

Biological memories of past environments: Epigenetic Pathways to health disparities

This article was rather interesting as it similar to the discussion we had in class on Tuesday on the lead affecting children. Following are just some summed points from each section of the paper.

Introduction

  • The introduction spoke about  current and recent research that environmental exposures can influence biology and health, which is epigenetics.
  • Although that has been studied, the linkage between environmental factors and patterns of disease through epigenetics processes.
  • Previous research has seen a deleterious health impacts of economic and status inequality, such as stress or discrimination. And that being of low social status increases disease risk.
  • Although these linkages are understood, the biology behind them isn't totally clear.
  • Studies like these are important from a public health perspective as they can help to understand where certain diseases are coming from.

Nutritional Stress

  • Nutritional status can influence epigenetic profiles.
  • Several studies have show than nutritional exposure during critical periods can significantly affect the life course of an individual. For instance a low protein maternal diet in rats led to increased risk of type 2 diabetes.
  • Nutritional epigenetic effects may extend into successive generations  through germ lines.  Food shortage in a generation may increase the grandchild's mortality risk from cardiovascular diseases.
  • Food security and access to food supplies affects functional outcomes in offspring.

Psychosocial Stress

  • Traditional studies of stress and health tend to involve blood pressure or hormone metabolism, but new research is trying to link psychosocial stress and epigenetically-based changes in gene regulation.
  • Data has shown that stress related epigenetic changes can be passed on to offspring, as with the stressed out rats, passing on their epigenetic profiles to their children.
  • Stress can also be varied in humans based on socio-economic status and other factors such as perceived discrimination. Differing levels of stress can cause certain groups to be at risk for different diseases and affects.

Environmental Toxicants

  • It is well known that toxic chemicals and materials can affect epigenetic markers and change gene expression. Heavy metals in particular have been seen to affect methylation (an important biological process whereby a methyl group is added to another biological compound) and serotonin production.
  • Exposure during pregnancy can modify genes and lead to eventual development of diseases down the road.
  • Certain chemical exposure can even affect several generations, as mice treated with an endocrine disruptor were seen to affected negatively sperm for several generations. This shows the long lasting effects of certain toxicants.

Future Directions

  • To get a better idea of what areas and groups to study we have to look at the underlying social structure.
  • Studies need to be conducted on the potential to change epigenetic linked diseases, not just conducted to identify them.
  • This knowledge of epigenetics needs to be brought to the public's attention and to the policy makers in an attempt to show how important environmental factors are on developing bodies.

Food for Thought

  • Are there other ill health effects that could potentially be linked to early epigenetic factors besides those mentioned in the article?
  • Can any other diseases previous attributed to other things, such as stress actually be epigenetic in origin?

9 thoughts on “Biological Memories and Epigenetics

  1. Emily Barron

    I didn't see fetal alcohol spectrum disorders or autism listed. I was reading an article earlier that linked epigenetics and Parkinson's.

  2. Jess Leonard

    I especially enjoyed the nod to "policy makers" at the end. I think it'll be interesting to see how, in the coming years, our understanding of these links between epigenetics and disease will shape public policy in healthcare. Also, if and when new methods for reversing deleterious epimutations are introduced, will the socioeconomic disparities mentioned in this article prevent individuals of the lower strata access to these new medicines?

  3. rebeccaleon

    Since the article mentioned some of the ways in which pollutants in our environment can affect our health there are other examples of how pollutants can affect humans epigenetically. Some of these include: A study of women in Taiwan and Japan found that women who were exposed to PCBs (polychlorinated biphenyl) had abnormal menstrual bleeding and girls who were exposed to PCBs in utero also had irregular menstrual cycles. Other studies have linked PCBs to reduced female fecundability (the probability that conception will occur in a given population during a specific time period); and higher rates of miscarriages, stillbirths, and preadolescent death.

    Studies have also found that obesity and diabetes are linked to the levels of dioxins (a type of POP) and PCBs. Someone’s risk for developing diabetes increases as their POP levels increase. A study conducted in Belgium found that individuals with diabetes had 39-62% higher POP levels than those who did not have diabetes. It is important here to point out that POPs like to attached themselves to fat, so this might explain why someone with higher POP levels are at higher risk of obesity or diabetes.

  4. Christopher Lynn

    You don't get credit for discussion if you didn't post commentary by the time I print this out (now). This one was posted in plenty of time.

  5. Pingback: Of Epigenetic Aggression & Silver Foxes: Updated–Now with More Methylation! | Biology, Culture, and Evolution

  6. Andrea Morris

    To answer the second question, obesity is one thing that could be epigenetic. A mother's diet during pregnant as well as a child's diet during development have high influences on wether or not an adult will become obese.

  7. Meghan Steel

    My main issue with this article arises from one of our earlier discussions about evolution. In a previous class, we talked about how natural selection can only improve a species fitness while genetic drift moves them through the "valleys." However, many epigenetic changes seem to be detrimental to the offsprings general health (eg the relationship between malnutrition during pregnancy and the child's predisposition to heart disease). Why have epigentic influences been selected for if many of them seem to decrease overall fitness?

  8. Sophia Fazal

    I know this doesn't address Meghan's comment directly, but there have been other ways that suggest for a resolution in the conflicts of negative epigenetic influences and their effects on decreasing overall fitness. The article that I'm linking below, even though you may only be able to see the abstract finds one way to go around the conflict of these negative influences. This is something that way brought to my attention by another student in the biology department when we talked about this subject, and I thought it was too interesting to pass up: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0070493.

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