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Just a little over a month ago now, our 23 and me DNA test results came in. After waiting only a few weeks for our spit to be analyzed, the data is all in.

My heritage wasn't particularly exciting, 93.2% was from South and Southern Europe. Although I did have 5.5% from Northern Europe. This could potentially back up one of my family member's claims that I had a great great grandfather or some-such, that was a Swedish sea captain. I also have .3% from the Middle east/North Africa, and <.1% from Oceania, which are both surprising.

When I look at my traits, I see that I am likely a taller than average male, with brown hair, brown eyes and a fast metabolism for caffeine. So, they more or less hit the nail on the head with this. And when I looked at my health risks, I see I am at a slightly increased risk for coronary disease, and a decreased risk for several other disorders and diseases.

This entire process was not only easier than I thought, but a lot faster as well. I would recommend this process to anyone wjo would want to learn more about their heritage and genome.

Fun Fact: the guys responsible for the song "What does the fox say?" did 23 and Me and had their results on their show.  I've linked the segment to the photo below.

I Kveld med Ylvis

6

 

bogin_528

Barry Bogin is an American physical anthropologist trained at Temple University that researches physical growth in Guatemalan Maya children, and is a theorist upon the evolutionary origins of human childhood. He is currently at Loughborough University in the UK. He is noted for the idea that evolution added two new stages into human development; childhood and adolescence.

 

Smith,B Holly

B. Holly Smith is a Associate Research Scientist in the Department of Anthropology at the University of Michigan at Ann Arbor where she got both her Master and Ph.D. She is interested in  how humans differ from other mammals in life cycle and life span, why we differ and whether we can reconstruct the evolutionary history of our life cycle from the fossil record.

This chapter was about the evolution and alterations of the human life cycle. The main questions that guided this research were:

  • How can human biologists identify the shared and novel features of the human life cycle?
  • Can the time of origin of the novel features be determined?
  • Can the reasons for the evolution of new growth development and maturation patters be determined?

 

Stages in the Life cycle

There are four main stages in the human life cycle Birth, Postnatal Development, Adulthood, and Death. Of these, both postnatal development and adulthood are divided up into sections. Pregnancy (the period before birth) is divided into trimesters and during this gestational period, the fetus grows and changes and experiences critical periods. These are times when a fetus is particularly susceptible to outside factors such as diseases or lack of nutrients. During this time the fetus can undergo epigenetic modification.

What other outside factors can affect a fetus in vivo?

 

After the pregnancy comes birth, a rapid transition from a fairly stable liquid environment to a volatile gaseous one. And after this period come the postnatal development. This is the most complex of the stages and is divided up into these sections

  • Neonatal period
  • Infancy
  • Childhood
  • Juvenile
  • Puberty
  • Adolescence

Which of these sections is the longest and why do you think that is?

In which of these stages is proper nutrition the most critical for brain development, and why is this so?

 

Why did new life stages evolve?

If we look at the life cycles of other large primates we see that although humans experience delays in Molar 1 eruptions, menarche and 1st births, humans have less spacing between births (3 years for humans, 6 for chimpanzees). This gives humans the advantage to give birth to more offspring. So we find that our evolution of childhood gives us the reproductive advantage although it does come with some drawbacks. Children need specialized diets and extended periods of care, as they do not become self sufficient until post-adolescence.

Although we cannot study the life cycles of an extinct organism, we can postulate it by looking at currently living species. In looking at archaeological evidence, we can see that there is an increase in brain size in cubic centimeters and that because of this, there had to have been an increase in postnatal stages. When we get to homo sapiens we see the appearance of adolescence.

Which organism(s) would be useful in looking at early human life cycles?

What physiological changes needed to occur in early human ancestors to accommodate larger brains?

 

Food for thought

  • How would we be different if we had a shorter postnatal period?
  • Would anything be different if humans waited (on average) twice as long between children?

9

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?

2

Recently, our anthropology class learned that we would have the option to participate in genetic testing from the company 23andMe.  This testing would potentially reveal both genetic ancestry and potential health risks.

Looking at their website, it's easy to become overwhelmed at the amount of things they test for, from the potential for migraines to the possibility of being a carrier for lethal diseases. But even so, I think it is not only worth it, but it's exciting. I'm most interested in  the testing for heritage. Most of my family is Southern European, from Croatia and Italy, but I've heard rumors of a distant grandfather who was a Swedish sea captain. While they cannot test for his occupation, it would be interesting to see if the genetic markers are there.

It would also be interesting to see the health information that comes with the tests. Apart from the risk factors, they test for genetic markers for other attributes, such as height, food preference,  and caffeine consumption. I'd really like to see if the data that comes back matches my actual profile.  As a 6'4" tall male, with a penchant for constantly drinking coffee, I would be mildly surprised if the results came back and said that I was genetically inclined towards neither.

As a class, we have not yet received our kits, and so we're all just working off of the data and information reported on their website. Personally, I think this will be a interesting experience to have, multiple people going through it at the same time, blogging about the process and sharing the results.

And as far as the testing goes, I am happy to contribute. Even if the data we receive back is not 100% conclusive on all points, we have each contributed a small portion to the better understanding of genetics and genetic testing. In a few years time, and with more participation, the tests could get much more accurate and comprehensive.