Bioarchaeological Approaches to the Past Chapter 9 Bioarchaeological Approaches to the Past

Outline Skeletal Analysis: The Basics How Well Did the Stillwater People Live? Reconstructing Diet from Human Bone Lives of Affluence? Or Nasty, Brutish, and Short? Archaeology and DNA

Skeletal Analysis: The Basics Archeological skeletal remains are often fragmented and withered, making them difficult to identify. Osteology, the study of bone Burial population – a set of human burials that come from a limited region and a limited time period (the more limited the region and time period, the more accurate will be inferences drawn from analysis of the burials.)

Major Bones of the Human Skeleton

Determining Sex Pelvic area, wider in women than men. Adult male skulls tend to be more robust than adult female skulls. Male skulls tend to have square chins and eye orbits. Sciatic notch – the angled edge of both halves of the posterior (rear) side of the pelvis. Width varies among populations, but narrow notches indicate a male and wider notches indicate a female.

Determining Age Teeth are extremely useful for telling the age of younger individuals. Patterns of bone fusion are also useful in youth skeletons. It is difficult to pin down the age of an individual older than 50 years. Epiphyses – the ends of bones that fuse to the main shaft or portion of bone at various ages Pubic symphysis – where two halves of the pelvis meet in the groin area

How Well did the Stillwater People Live? The Stillwater burials derived from a 16-square kilometer area of marsh. Few of the burials contained grave goods. Bioarchaelogist Larson derived how many men, women, infants, and adolescents there were and their approximate ages. Bioarchaeology-The study of the human biological component of the archaeological record.

How Well did the Stillwater People Live? Paleopathology-the study of ancient diseases, disorders and trauma. Bioarcheaology-The study of the human biological component of the archaeological record Few specific diseases can be identified from bones. The study of biological stress has become an important area of bioarchaeology.

Disease and Trauma at Stillwater Larson found signs of iron deficiency anemia among the skeletal remains from Stillwater Marsh. Every single adult skeleton in the Stillwater collection had osteoarthritis in at least one joint. The femur cross sections and patterns in osteoarthritis indicated that the people living at Stillwater Marsh walked a great deal to make a successful living.

Growth-Arrest Features Childhood growth may be periodically arrested because of disease, trauma, or malnutrition. Whenever this happens, bones records the cessation of growth. Teeth register the cessation of growth. Growth arrest is forever encoded as shallow grooves known as enamel hypoplasias.

Workload Bones have memories. Bones can be hard to read but they do not lie. Bioarchaeologists use a variety of ways to determine how much physical labor a person did through life. Osteoarthritis is a joint disorder created by the loss of cartilage, often caused by mechanical stress. Eburnation a sign of osteoarthritis in which the epitasis of long bones are worn smooth.

The Stillwater Mortality Profile

Paleodemography Paleodemography reconstructs parameters such as life expectancy at birth, the age profile of a population, and patterns in the ages of death. Mortality profiles show at what age adult males, adult females, and children died. The femur is the best bone for computing stature. Height provides a useful measure of overall health because it is closely related to diet.

Reconstructing Diet from Human Bone Diet can be reconstructed from human bone in several ways. Dental caries can help differentiate between agriculturalists and hunter-gatherers populations. Cavities indicate a starchy diet. Because their diet was low in simple carbohydrates, only 3 percent of Stillwater skeletons had cavities. Bioarchaeologists can glance at a subject’s and make a good guess as to whether the person was an agriculturalist or a forager.

Bone and Stable Isotopes Ancient diets can also be reconstructed by analyzing the carbon and nitrogen stable isotopes preserved in human bone. Human bones reflect the isotopic ratios of plants ingested during life. We reconstruct the dietary importance of plants by measuring the ratio of carbon isotopes in bone collagen. A diet rich in C4 plants (maize), can produce bones with a higher ratio of 13C to 12C. Humans who consume large amounts of meat have a higher ratio of 15N to 14N. Differences in nitrogen value tell us whether people relied more heavily on marine or terrestrial (meat) food.

Life of Affluence? Or Nasty, Brutish, and Short? Archaeologists try to understand the various factors that influence diet. Rates of infections and bone breakage, workloads and dental health. In some ways, the Stillwater people had a good life, in other ways, it was not that easy. The past can almost never be characterized in simple black and white terms.

Archaeology & DNA Geneticists and archaeologists have joined forces to create a new approach to reconstructing the past, known as molecular archaeology.

Background on DNA Most of our genetic information exists as about 3 billion nucleotides based pairs grouped in some 50,000 genes on the 46 chromosomes, inside the nucleus of each cell in our body. Although nuclear DNA is extremely useful to the genetics of living populations, it is not so useful to archaeology, it degrades fairly quickly. Gene – A unit of the chromosomes that controls inheritance of particular traits.

Background on DNA mitochondrial DNA (mtDNA) – Genetic material found in the mitochondria of cells; inherited only from the mother, mutates at a rate of 2 to 4 percent per 1 million years. mtDNA 3 interesting properties: Each cell contains thousands of copies of the total genetic recipe. Its recovery is made possible through polymerase chain reaction (PCR). It is inherited only from the mother. It appears to be under less selective pressure than nuclear DNA. mtDNA appears to change as a result of random mutations. mtDNA is sometimes used as a clock to date the timing of human population movements in the past.

Prospecting for Ancient DNA In 1984, Allan Wilson and his student Vince Sarich were the first to identify genetic materials from old tissue. The next year, Swedish researcher Svante Pääbo cloned DNA from a 4,400-year-old Egyptian mummy. This was the first time that anyone had applied PCR techniques to ancient humans.

An African Eve? Wilson and his team continued to collect mtDNA samples from around the world and compared the human data with that of chimpanzees. All living human groups share all but about 0.6 percent mtDNA. The 0.6 percent suggests a way to determine the relatedness among living individuals and groups. Africa provided the longest branch on the tree, suggesting this is where human mtDNA began to differentiate. Wilson’s molecular clock suggest that Eve must have lived about 200,000years ago.

What Happened to the Neanderthals? Neanderthals were in Europe at least 500K.Y.A. Skeletal data shows striking biological differences from modern humans. Generally more robust and muscular and genetic study found they generally had lighter skin and red hair. In 20120 geneticists led by Svante Pääbo sequenced the nDNA genome from three Neanderthals. Neanderthasl and humans interbred 40-50,000 years ago and produce fertile offspring.

Relevant Videos TED Svante Paabo: DNA http://www.youtube.com/watch?v=vqsqfpd0wmw The Real Eve http://www.youtube.com/watch?v=oAXt2AUwPm0 The Neanderthals Genome Project http://www.youtube.com/watch?v=GuIRjtZJGmQ National Geographic: Last Neanderthal http://ngm.nationalgeographic.com/video/player#/?titl eID=neanderthals&catID=1

Quick Quiz

Learning the origin and distribution of disease. 1. Bioarchaeology is used in the following types of research: Learning the origin and distribution of disease. Reconstructing human diets. Analyzing evidence for biological stress in archaeological populations. All of the above.

Answer: D Bioarchaeology is used to learn the origin and distribution of disease, reconstruct human diets and analyze evidence for biological stress in archaeological populations.

2. Characteristics of the pelvis and skull can help to determine an individual’s ____, while ____ can be determined by tooth eruption.

Answer: sex; age Characteristics of the the pelvis and skull can help to determine an individual’s sex while age can be determined by tooth eruption.

3. Paleodemography reconstructs parameters such as: life expectancy at birth. age profile of a population. population migrations. A and B only. A, B and C.

Answer: D Paleodemography reconstructs parameters such as life expectancy at birth and the age profile of a population.

4. The _____ ______ calculates the time since divergence of two related populations using the presumed rate of mutation in mtDNA and the genetic differences between the two populations.

Answer: molecular clock The Molecular Clock calculates the time since divergence of two related populations using the presumed rate of mutation in mtDNA and the genetic differences between the two populations.