I was excited to receive the results of my 23andMe test this past week. I had been interested to see the results of my heritage as well as the health risks I am prevalent to in the future. The three diseases I am most prone to are coronary heart disease, type two diabetes, and breast cancer. None of these are too shocking because I have had family members that have had these diseases. My ancestry was not much of a surprise either, but it was still interesting to find out more about where my family came from. I am 99.7% european which is not a shock at all based on my skin, eye, and hair color. I am .1% Native American and 2.8% neanderthal which is slightly above average. The only issue I had with the test is that it could not determine my paternal lineage. This is obviously because I am a woman and do not have the y chromosome. The only way I would obtain this information would be if my dad also did the 23andMe test. Overall, my results showed nothing that shocked me, but they were still interesting to learn about.
Author Biography: James Josh Snodgrass
Dr. J. Snodgrass’ research interest cover almost every topic related to human biology: adaptations and evolution, nutrition, epidemiology, and the social/behavioral patterns that emerge from them. Specifically, he focuses on elucidating the effect of economic and cultural change plus chronic psychosocial stress on human health patterns, human adaptations to environmental extremes, and energetics and the role of evolution in shaping the human diet. His ongoing work includes the Indigenous Siberian Health and Adaptation Project, The Shuar Health and Life History Project in Ecuador, and his collaborative efforts in studying stress, discrimination, and health among Latin American immigrants in Oregon. His publication topics range from the metabolic correlates to hominid brain expansion to the immergence of obesity in indigenous Siberian populations to muscle mass scaling in primates. He has even published work in the Journal of Forensic Science concerning sex related differences in the aging of the vertebral column and parity assessment utilizing the dorsal pits and pubic tubercle height. He is the membership chair on the executive committee for the American Association of Physical Anthropologists, an advisor for the multi-country studies unit for the World Health Organization, and the director of the Human Biology Research Laboratory at the University of Oregon. He recently received the Michael A. Little Early Career award for his outstanding contributions to the field of human biology, and has been distinguished multiple times for his excellent work as an educator and scientist. Currently, he works at the University of Oregon teaching classes on human growth and development, human biological variation, and evolutionary medicine.
What is energetics and how does it fit into anthropology?
Energetics is the study of the use and transfer of energy. Anthropologists use energetics in order to examine issues within human biology such as the origins of bipedalism and encephalization, prevalence of obesity, growth patterns, human adaption to climate change, influence of diet and physical activity on the reproductive system. The anthropological approach to energetics focuses on how energy is extracted form the environment and affects human’s health, survival, and reproduction.
Basic Principles of Energetics
The foundation of energetics is based on energy transfer. This is how chemical energy is extracted from food and turned into energy for the function of day-to-day activities.
Three purposes that food energy is obtained:
1) Biosynthesis- synthesis of cells, tissues, and organic materials
2) Somatic maintenance- repertory, circulatory, and nervous system activity (internal work)
3) Muscular work for physical activity (external work)
Due to the need for the internal and external needs, mammals and homeotherms must eat regularly in order to produce the chemical energy necessary for these functions.
Metabolism and Dietary Sources of Energy
- The metabolic rate is the rate of energy turnover expressed in calories or joules per unit time. An animal's metabolic rate is shaped by size, age, sex, activity level, and environment temperature. An animal's body size has been recognized to correlate with its metabolic rate. An animal's resting metabolic rate (RMR) as well a their total daily energy expenditure (TDEE) also correlate with their size. Metabolic rates vary based on size. Animals with who have a large body masses have low metabolic rate and animals with size a small body mass have high metabolic rates.
- Adenosine triphosphate (ATP) is the most important energy currency in the body. It is formed by oxidation of glucose during cellular resperation and its ultimate use is to perform physical work. The way in which energy is provided for the ATP is through macronutrients. This uses carbs, proteins, fats, and alcohol to provide energy for the ATP. The amount of macronutrients consumed effects the dietary patterns for different cultures.
When the expenditure of energy is greater than the energy consumption the body’s mass, fat, and tissue are reduced. When the expenditure of energy is less than the energy consumption then the body retains fat. The body fat percentage varies in different cultures as well as mammals species. Cultures with more plentiful calories have higher body fat.
- BMR is the amount of energy used while awake. This occupies 45-70% of the total energy expenditure (TEE). The TEE is the total metabolic costs that come from physical activity within a 24 hour period. The BMR is correlated with body mass and varies between different sexes and can fluctuate with age.
- Maintenance costs contribute to a populations energy requirements . Thermic effect of food (TEF), thermoregulation, immune function, physical activity, growth, and reproduction are all ways in which energy costs can be measured. TEF measures the cost of energy through the digestion, absorption, and oxidation of food. Thermoregulation consists of two components: obligatory and facultative thermoregulation. Obligatory thermoregulation produces heat from maintenance metabolism and maintains the human body temperature in the thermoneutral range (77-81° F). Facultative thermoregulation allows the body to maintain homeostasis. Immune functions are the cost of energy for the body to fight diseases, maintain core temperature, and producing antibody responses. Physical activity measure the energy costs through voluntary activity. Growth and reproduction take into account the amount of energy it takes for the body to change over time and for the female body to undergo pregnancy.
Measuring Energy Intake and Energy Balance
- Energy intake is measuring the energy intake available in the food supply in a population. Ways of measuring this are by dietary records which are sometimes followed by and dietary recalls. The dietary records requires participants to record all nutrients consumed over a specific time period (usually a few days). They must record ingredients and volume of the food and liquids they’ve consumed. This allows for more accurate results of a dietary recall is to follow.The dietary recall requires participants to recall the quantity of food they have consumed over the last 24 hours. This can be performed through surveys or interviews and allows researchers to analyze nutrition consumption amongst populations. These records allow for anthropologists to analyze a population's energy intake by the energy available in their diets.
- Nutritional intake refers to body size and body fat as long-term measures of energy balance. Ways of measuring body fat are by measuring skinfolds (sum of four skinfolds taken at a skin fold site), using bioelectrical impedance analysis, and calculating the body mass index (BMI).
Physical activity is the cost of human movement. This is measured in Activity energy expenditure (AEE)
- Measuring Physical Activity- The book discusses two main methods that help measure physical activity patterns in everyday life.DLW (doubly labeled water) uses two isotopes of water to calculate the TEE. By orally taking the isotopes and monitoring them for a week or two, the carbon dioxide production made from the disappearing isotopes helps calculate the TEE. The second HR (heart rate) Monitoring uses the HR and energy expenditure to calculate the TEE. A HR monitor is worn during the time in which the participant is active. The participant’s average energy expenditure is analyzed by the HR monitor over the span of a few days.
Have any of you ever used a HR monitor before? If so, what was your experience using it?
Why do you think it is important that we measure physical activity?
Energetics and Human Evolutionary History
- What are some of the evolutionary adaptations along the early hominin line and what energy trade-offs occurred based on these changes?
- Bipedalism- Conserves more energy than quadrapedalism at walking speeds, but requires more effort to move faster
- Encephalization- While overall caloric intake remains at a level predicted by trends among other primate species, a far greater portion of those calories is dedicated to brain functions (~20%)
- Dietary switch to more nutrient dense foods
- Required a subsequent reduction in colon size and dietary thermogenesis
Energetics and Adaptations in Modern Populations
- What are some environmental stressors that require changes in energetics within the human populations that live there?
- Thermal Stress
- ~3% increase in BMR for every 10 degrees C drop in temperature (below the baseline of 10 degrees C)
- High heritability effect, since a study has revealed higher BMRs in the indigenous population than the non-indigenous immigrants
- Genetic studies focus heavily on mitochondrial DNA and the corresponding haplogroups
- Thermal Stress
- Seasonal Stress
- Several populations faced with severe, season-based energy shortages
- Compensations include cultural adaptations such as migration and food storage
- A major adaptation: seasonality of reproduction, helps pregnant women sustain a healthier weight during term and to buffer the extra energy requirements of lactation
Energetics and Health
- What are some of the problems that humans face when attempting to regulate energetics?
- Can be either acute or chronic
- Particular problematic in juveniles
- Stunted= Low height for weight
- Wasted= Low weight for height
- Underweight= Low weight for age
- Results in reduced physical activity and down regulation of the BMR
- Many communities facing a double-edged sword: Undernutrition among adolescents and overnutrition among adults
- Heavily correlated with the obesity epidemic
- Previously considered a disease of affluence, but the reduction in price of refined carbs and sugars has made them more available to groups of a lower social economic status
- People are receiving a surplus energy supply but not enough micronutrients
- Accompanied by a reduction in overall activity level
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.
About the Authors
Mark L. Weiss, Ph.D.
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).
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 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
- Two kinds
DNA’s Two Roles
- It must be able to transmit information from one generation to the next
- Directing the production of proteins
- 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
- 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
- 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
- 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)
- 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
- 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
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?