Skip to content

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.

8

About the Authors

Dr. Dennis O'Rourke is the Interim Chair of the Anthropology Department at the University of Utah in Salt Lake City, Utah. He is also the Co-Chair of the International Review Board and Vice President of Research. Dr. O'Rourke received his BA (with Honors), MA and PhD in Anthropology  from the University of Kansas in 1973, 1976 and 1980. He then went on to his Post-Doctoral fellowship in the St. Louis School of Medicine at Washington University. There he focused on Psychiatry/Genetic Epidemiology.

As mentioned before in @rebeccaleon blog from week one of class;  Dr. O'Rourke work focuses on the sampling and analysis of ancient DNA,  quantitative methods, and population and evolutionary genetics. The areas and populations that he focuses on are native America, and the North American and Siberian Arctic.

4330575969_fa1ef6ab2d
Picture of Jake Enk cutting a Mammoth tooth.

Jake Enk is a Doctoral student at McMatser University in Hamilton, Ontario. He received his Masters at The University of Utah.

In reading this chapter of Human Biology (Chapter 4), the authors bring into focus the effects of genetics on human populations in reference to geography and how understanding these topics can be, at best, informative to the history of our species and, at worst, complicated or even convoluted. The equations aside (which are, admittedly,  of great importance in the derivation of these data), in this chapter we delve deeply into understanding the mechanics of mutation , the interplay between human migration and genetic information, and how these factors shape our, often debated, view of how human populations came into existence and continued to move around the globe.

The chapter begins with explanations of basic evolutionary factors, specifically how mutations come to prominence in populations and how not only natural selection, but population size directly affects how readily mutations take hold. In somewhat simpler terms, the smaller the population, the more readily the frequency of an advantageous allele will increase within that population (There’s a convenient figure on p.108 that lays it out for you). As interesting as data acquisition and these formulas are, the real meat of Chapter 4 lies within the application of these methods to understanding our species’ history and how this data can better serve that purpose.

To begin, we can challenge, disprove, or validate many earlier assumptions of this field through the use of genetics as evidence. One great example Chapter 4 illustrates is Hrdlička’s hypothesis of a replacement population in the Aleutian Islands roughly a thousand years ago. His 1945 work, based mainly on differences in cranial forms, hypothesized an existing Aleutian population being replaced by a wave of newcomers who would become the ancestors of modern Aleuts. While his assumptions weren’t definitive beyond a shadow of a doubt, modern genetic testing (after a few upsets with unfortunately small sample sizes) has proven his work correct, contributing even more validity to our understanding of human history.

Sometimes, however, this availability of new data can obscure what was previously seen as a clean-cut understanding of that history. The authors bring up the issue of the presence of Neanderthal genetic information in modern human and the debate as to how it got there, if it is Neanderthal DNA in the first place. Sequencing of Mitochondrial DNA from Neanderthals show incredible variation from modern humans and ancient anatomically modern humans (supporting that long-held belief that humans and Neanderthals never interbred), yet nuclear genome sequences suggest that one to four percent of our genome may be made up from Neanderthal DNA, possibly from admixture. So did early humans and Neanderthals mate, or could these traits be the result of latent genetic traits that we both received form an ancient ancestor? The answer: we don’t know. Maybe both. Perhaps you’ll be the ones to figure it out.

Finally, this chapter shows how even our understanding of genetic data in relation to prehistoric human events can be far more complicated than that data would initially suggest. In the example of the populating of Europe, differences in mitochondrial DNA and nuclear molecular DNA, which seem incompatible, illustrated a far richer story. In this case, the mitochondrial DNA suggests a movement of humans into Europe from the Middle East, roughly 10,000 years ago, coinciding with the advent of agriculture. The nuclear molecular DNA evidence, however, suggests something much different. Rather than 10,000 years ago, this evidence suggests a divergence in populations from 46,000 to 130,000 years ago. So which evidence is correct? Both. By comparing and combining these data, human biologist now surmise that while a clinal migration from the Middle East into Europe did take place around 10,000 years ago, Europe had already been populated by Homo Sapiens long before that event.

All in all, this chapter is helpful in illustrating the importance of genetic information and its contribution to our understanding of the human story. If you want to know the specifics of how DNA evidence is used to formulate new hypotheses and support or refute existing ones: this is the chapter for you... But don’t take our word for it! (Insert Reading Rainbow theme here)

1) What do you believe the current genetic distance is? Is this a good thing or bad thing?

2) What are some current examples of migration? And how have they influenced the current gene population?

1

This semester our class has been granted the opportunity to participate in the 23andMe testing.  I had heard of this testing before, but never thought I'd have the opportunity to do it myself. The thought of knowing the origins of my ancestors as well as hundreds of different facts about my health is both exciting and daunting.

What I am most looking forward to about this testing is seeing where my ancestral roots lie and to learn and gain an in-depth understanding of my overall health.  What I have been told of my heritage is that I am mostly of european descent, specifically from the United Kingdom. I will be interested to see is 23andMe proves this information to be true or if there is another origin that  is more dominant.  I will also be interested to see if there is any information about my health that will be surprising. I know that I am already prone to having thyroid issues in the future, type 2 diabetes, and certain kinds of cancer. Aside from those I will be interested to see if there are any other conditions that I will need to take into consideration in the future. This leads to the only concern I have with the 23andMe testing. I am concerned that I may I am prone to a certain health condition that is serious or has no treatment. The pros to finding out such information, however, would be that I could take steps towards preventing any health issue s that could arise in the future.

Overall I am looking forward to receiving my 23andMe results because I think they will be interesting to read and I think the information the results will provide will prove to be beneficial. It will also be interesting to hear about the results of my classmates and compare and contrasts results. This testing will help us to analyze how different people's heritage may make them more like to have a certain trait or develop a certain health condition.

 

1

About the Authors

Unknown-3

 

Mark L. Weiss, Ph.D.

Professor

Department of Anatomy and Physiology at Kansas State University

Professor Weiss is part of the KSU Stem Cell Biotechnology Research team where his current work has been to focus on characterizing non-embryonic stem cells that have been discovered in the umbilical cord matrix and rat embryonic stem cell.  The point of this research is to characterize the role of human and animal umbilical cord matrix stem cells to reverse the behavioral deficits in a rat model of Parkinson’s disease.  Dr. Weiss received his Ph.D in biology from the University of Pennsylvania (1986) and in his postdoctoral from Michigan State University (1986-1989).

Justin Tackney

Ph.D. Graduate Research Assistant

Department of Anthropology at the University of Utah

Justin Tackney is a Ph.D. graduate student studying social and behavioral sciences at the University of Utah

Basic Genetics

  • Basic concepts formed by Gregor Mendel (1822-1884)
  • Mendel conducted series of experiments on the passage of traits from generation to generation of pea plants.
  • Key Terms created by Mendel:
    • Gene- The basic unit of inheritance; each parent contributes on copy
    • Diploid State- cells that contain two genes for each trait
    • Mendel’s Principle of Segregation- States that each sexually reproducing organism has two genes per trait, but only one pair of each gene is passed on to the offspring of the parents.
    • Meiosis- The reproduction of haploid gametes (sex cells)
    • Mitosis- Process of cell division producing cells with same number of chromosomes as parental cell
    • Recombination- Process of forming associations of genes at different loci after chromosomal crossing over
    • Allele- Various forms of a gene
    • Homozygous- Possessing two identical alleles for a trait
    • Heterozygous- Possessing two different alleles for a trait
    • Genotype- Combination of alleles that one posses for a specific trait
    • Phenotype- Visible appearance of trait
    • Dominate Trait- When an allele masks the presence of another allele
    • Recessive Trait- The allele that is masked by the dominate trait.
    • Codominate Trait- When an allele is neither dominate or recessive. Both are expressed in the phenotype.
    • Genes are composed of nucleic acids
      • Two kinds
        • DNA (deoxyribonucleic acid)- the genetic material for most species
        • RNA (ribonucleic acid)- nucleic acid where the sugar is the backbone and substitution of uracil for thymine
          • These nucleic acids transmit information
          • In humans, DNA is the genetic material and the RNA helps the DNA carry out tasks

DNA’s Two Roles

  1. It must be able to transmit information from one generation to the next
  2. Directing the production of proteins

DNA Replication

  • DNA Replication is semiconservative. This means that one double strand of DNA serves as the basis for making two double strands; each of the new double strands contains one old and one new strand of DNA.
  • DNA is able to reproduce with few errors due to the constructing pairing
  • Mutation- Alteration in the DNA sequence

DNA Makes Protein

  • Most genes direct the production of polypeptide chains. These are then assembled into protein s
  • Proteins- molecules constructed out of amino acids
    • Twenty amino acids are arranged into protein molecules
    • Thymine pairs with adenine (T-A)
    • Cytosine pairs with guanine (C-G)
    • DNA is located in the nucleus of the cell
    • Proteins and ribosomes are assembled in the cytoplasm
    • Transcription- process by which mRNA is constructed
    • DNA is constructed in a double helix
    • Transcription- Process of converting DNA into RNA
    • Translation- Process of converting mRNA into amino acid.

Studying the DNA

  • Major developments in the study of DNA
    • Restriction enzymes- Due to their discovery the cutting of DNA is now more predictable. This allows one to produce recombinant DNA.
    • Polymerase chain reaction (PCR)- Technique that allows researchers to reproduce almost limitless copies of DNA by using only one piece of it.
      • This has been helpful to anthropologists who deal with ancient bone and tissue

Gene Structure

  • Eukaryotes- Organisms with a nucleus
    • Split into alternating DNA segments
    • Exon- DNA sequence that is expressed
    • Interons or IVSs- unexpressed sequences
  • Prokaryotes- Organisms without a nucleus

Gene Families

  • Some genes are similar to other in their functions and evolutionary history
  • Gene families help to connect one species to another throughout evolution
  • Gene families can be analyzed for gene duplication and divergence

Other sorts of DNA

  • DNA is contained inside chromatin because all of our DNA cannot fit into a nucleus
  • Purifying selection- method for identifying functional genome sequences

Pseudogenes

  • Non-functional DNA sequence that has a resemblance of a functional gene
  • May represent the relics of once- functional genes that experienced a mutation that prevented their expression

Repetitive DNA Sequences

  • Sometimes referred to as satellite DNA
  • Three types
    • a-satellite DNA
    • minisatellite DNA
    • microsatellites or short tandem repeats (STRs)

Mitochondrial DNA

  • Referred to as mtDNA
  • Maternally inherited DNA found in the mitochondria
  • Resent study of mtDNA in the mid-1980’s indicated an earlier divergence of human groups
  • Allowed for a common ancestor in Africa to be discovered
  • Used to help reconstruct the human population history
  • Used to decipher interplay between social rules and genetic phenomena

The Y Chromosome

  • Y contains few genes and is small in size compared to the X chromosome
  • The Y chromosome in chimps and gorillas does not have the same sequences as humans
    • This implies they have gone under alterations since humans diverged

Comparing the Human and Chimpanzee Genomes

  • Differences
    • Human chromosome 2 evolved from two ancestral chromosomes still present in apes
    • There are none pericentric chromosomal inversions in humans but not chimps
    • Human chromosomes have human-specific heterochromatin additions and apes do not have this

Pattering in the Genes

  • Genetic variants in human can be used to trace back lines of evolutionary relatedness between populations and other parts of human population history
  • Evidence that a small number of critical genetic changes cause significant change in a phenotype.

Rise of Genomics

  • Genomics helps give a better understanding of what defines us as Homosapiens. This can help us trace back our lineage.

Genetics and the Evolution of the Modern Human Brain

  • Researchers are hoping to eventually discover what lead to humans having distinctively large brains
    • This trait cannot be limited to protein- coding loci and must extend to proteins that regulate the expressions of proteins

8

After reading the chapter on genetics here are some discussion questions dealing with DNA and genetics:

1) After learning that we will have the opportunity to participate in the 23andMe testing, what do you think the benefits would be of having the 23andMe testing available to the public so everyone could have it done if the wanted? Would there be any setbacks?

2) As mentioned in the chapter, much more information has been revealed about our DNA over the past few decades. "This new information has sparked growth and progress in fields as diverse as law enforcement (through forensic analysis), medicine, population genetics, and endangered species conservation." Can you think of specific examples of how the DNA research can help the fields specified.

3) What are the benefits of advancing the of genomic methods?

17

Biographies

Michael A. Little

Dr. Michael A. Little possesses the title of “distinguished professor” at Pennsylvania State University (where he also earned both his masters and PhD). He began his research career examining cold adaptation in the high Peruvian Andes before he began a 20 year, multidisciplinary project that studied the health, biology, and culture of pastoralists in northwest Kenya. His current work focuses mainly on documenting the history of biological anthropology mainly, through archival research. He teaches classes at PSU on comparative human growth, human biological variation, and the history of biological anthropology. In 2005, he received the Franz Boas award from the Human Biology Association and later, in 2007, received the Charles R. Darwin award from the American Association of Physical Anthropologists.

Francis E. Johnston

Dr. Francis E. Johnston is Professor Emeritus of Anthropology at the University of Pennsylvania, where he also earned his PhD (his masters was earned at the University of Kentucky). He specializes in the study of the development of children in Latin America, particularly in regard to nutritional status and health. He is the founder and director of the Urban Nutrition Initiative. He was President of the American Association of Physical Anthropologists from 1983 to 1985 and has been the Editor-in-Chief of The American Journal of Physical Anthropology, Human Biology, and The American Journal of Human Biology (where he was also founding editor). In 2003, he received the Charles Darwin Lifetime Achievement Award of the American Association of Physical Anthropologists.

Human Biology and Its History

  • Timeline
    • Middle Ages: the earliest form of human biology begins with the study of cadavers to determine bodily structure
    • 1924: Raymond Pearl is the first modern scholar to use the term human biology
      • Discussion: Since this chapter focuses only on the history of American human biology (due to space restrictions), what kind of biases do you think could be present, if any?

Human Variation

  • Timeline
    • 1850-1940s: the measurement and description of past and present humans in the form of a typology is popular
      • Typologies can be problematic since they represent more of an idealized image than reality.
      • Eugenics arguing for the superiority of Western Europeans were popular at the time
      • It was believed that all races were: 1) fixed, 2) came from three primary races, and 3) were one of the primary races or a mixture of two or three primary races
      • 1897: Franz Boaz measured the heads of migrants and their children, showing that the environment and plasticity were important factors in variation
        • He stated that race and culture were separate
      • 1950: The new phase of physical anthropology begins with a conference held by Theodosius Dobzhansky and Sherwood Washburn
        • The use of the scientific method in the study of evolutionary theory became the new focus of this phase of anthropology
      • 1950: Races: A study of the Problem of Race Formation in Man, written by Carleton Coon, Stanley Garn, and Joseph Birdsell, argues that racial categories formed to the conditions of the environment via natural selection
        • Race was seen as ever-changing instead of static
      • Currently: race is no longer a subject of study, with the exception of clarifying misusages of the term that lead to discrimination. Human variation is viewed as dynamic.
        • Discussion: What are some current examples of the misuse of the concept of race? How are these examples different from misusages in the past?

Human Adaptability

  • 1950s: Bodily adaptation to the environment is viewed as happening largely in terms of adaptation to climate (particularly temperature extremes)
  • 1960s—1970s: The International Council of Scientific Unions (ICSU) implemented the International Biological Programme (IBP)
    • Human adaptability studies were a part of this, though the more scientifically inclined methodology of the research kept some human biologists from participating
    • Ecosystems science (a combination of ecology and the mathematical study of systems science) became popular
    • The physiological measurements that were also taken at this time allowed for the study of how populations adapt biobehaviorally to the environment
    • Many of the projects conducted by the human adaptability section of the IBP were multidisciplinary projects
      • Discussion: What are the advantages and disadvantages of a large-scale study such as the human adaptability research at the IBP?

Anthropological Genetics

  • Timeline
    • 1860’s- Mendel experiments with peas to develop the laws of  segregation and independent assortment
      • Explores dominance in alleles
      • Compares genotype to phenotype
    • 1927-1930- JBS Haldane and Robert Fisher expressed evolution as the aggregate effect of interactions between mutations, gene flow, selection, and genetic drift
      • Integrated Darwinian theory, population genetics, and advanced mathematical analyses
      • Let to the rise of the two modern approaches to the interpretation of patterns of gene frequency
        • One focuses on natural selection
        • One focuses on the stochastic processes of genetic drift and gene flow
    • 1900- Karl Landsteiner provides first description of human ABO blood type groups
      • Discovery of these and other antigens revolutionized immunology and segued into the study of human population genetics
      • Later found that the frequencies of these antigens are shaped, at least in a small degree, by natural selection
    • 1950- William Boyd argues against the use of anthropometry
      • Wanted scientists to focus on genetics that were not shaped by environment
      • Still believed in race as a true biological category
    • 1958- Frank B. Livingstone analyzes the distribution and dynamics  of the hemoglobin S (sickle-cell) gene
    • 1987- National Institutes of Health begin the Human Genome Project
  • Review and Discussion
    • Darwin’s description of natural selection was not complete until Mendel completed his work with the pea plants
      • Where do you stand on the issue of the main force behind evolution? Do you agree with E.B. Ford who argues that genetic polymorphism is maintained by selection and that gene frequencies are kept in equilibrium by opposing selective forces? Would  you say that population demographics like age structure, mortality rates, sex ratio, and migration/immigration patterns have the strongest  impact on the genetic variability within a population?
    • The Modern Trends
      • Most of the study of human genetics has  been at the level of DNA
      • The Human Genome Project focuses mainly on alleles considered responsible for disease
        • What else could be studied through the mapping of the human genome?
        • What portion of disease patterns do you consider to be affected by genetics and what portion of the pattern is affected by culture/environment?

Growth and Development

  • Timeline
    • 1948- Wilton M. Krogman starts to study the “whole child” and is       considered the “father” of growth studies in America
    • 1970- Though incorrect, Rose Frisch developed a hypothesis about the relationship between a “critical weight” and menarche in young females, thus sparking the interest in reproductive ecology popular in the 1980’s
    • 1986- Elizabeth Watts introduces an evolutionary perspective to the study of human growth
  • Review and Discussion
    • Franz Boas is considered the first to emphasize longitudinal studies when examining growth and development?
      • Why had few people done these before? What are the benefits? Do the benefits outweigh the numerous complications?
    • The new interest in human growth also opened new avenues on exploring the interactions between biology and the environment
      • Human ecology emerges, initiating studies that examine the physical changes that occur in people who live in extreme conditions
      • The exploration into the sub-division of reproductive ecology led to the discovery of the many environmental (and cultural) variables that influence reproduction and infant care
      • What framework were anthropologists previously using to examine         reproduction? 
    • The thrifty phenotype
      • First appears in the early 90’s
      • Based on the concept of developmental plasticity
      • States that some adult diseases can be associated with earlier growth patterns
      • How do you feel about the accuracy of this hypothesis? How could it be tested?

Biomedical Anthropology

  • Timeline
    • ~1960- Albert Damon describes the health significance in variations in physique
  • Review and Discussion
    • Four related factors that culminate in the discipline known as “biomedical anthropology"
        • The plasticity of human variability
        • Concept of “risk factors” refined by the field of epidemiology
        • Primary affiliation of many “human biologist” with the medical or dental industries
          • How would having a medical background assist a physical anthropologist? Could it be a hindrance? Or does it not really make a significant difference? 
        • The emergence of Darwinian (evolutionary) medicine
          • Examines the evolutionary aspects of contemporary human diseases
          • Includes “diseases of civilization,” representative of the fact that early adaptations to preindustrial life have become maladaptive in a contemporary, urban society
            • The book lists obesity, cardiovascular disease, and sudden infant death syndrome as examples, can you think of any others?
        • The realization of functional lifestyle changes that occur in immigrant populations
          • Focuses particularly on stress arising from culture shock and a change in social structure
          • Can culture also “cure” some of these stresses by providing a new form of adaptation?  

two trees

Follow evolution public service announcements on Tumbler!