Chapter 12

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: Tracing Human

Migrations

Bioarchaeology• The study of the human biological

component of the archaeological record by exploring bone, bone chemistry, and DNA preserved in human tissues to:– Learn the origin and distribution of

disease– Reconstruct human diets– Analyze evidence for biological stress

in archaeological populations

Skeletal Analysis:The Basics

• We use characteristics of several bones, notably the pelvis and skull, to determine an individual’s sex.

• An individual’s age can be determined by tooth eruption.

• Patterns of bone fusion, tooth wear, and bone wear are used to age individuals over the age of 25.

Some Major Bones of the Human Skeleton

The Stillwater People• 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.

Paleopathology and the Stillwater people

• Larsen turned to paleopathology, the study of ancient disease, to learn more about the Stillwater people.

• Larsen looked for nonspecific indicators of stress caused by nutritional deficiency and infectious diseases.

Environmental factors and Imprints on Human

Bone

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.

Paleodemography• Paleodemography reconstructs

parameters such as life expectancy at birth, the age profile of a population, and patterns in the ages of death.

• Bioarchaeologists do this by constructing various sorts of mortality profiles for a prehistoric population based on the age and sex data of burials.

• Mortality profiles show at what age adult males, adult females, and children died.

The Stillwater Mortality Profile

The Stillwater Mortality Profile

• Mortality of newborns and toddlers is very high among hunting and gathering populations.

• The female mortality profile shows an increase in deaths in the early child-bearing years; common for foraging populations.

• Few individuals are assigned to the 46–50 and 50+ age categories. A 47-year-old in Stillwater was an elder.

Reconstructing Diet from Human Bone

• Diet can be reconstructed from human bone in several ways.

• Cavities indicate a starchy diet.– Because their diet was low in simple

carbohydrates, only 3% of Stillwater skeletons had cavities.

• Ancient diets can also be reconstructed by analyzing the carbon and nitrogen stable isotopes preserved in human bone.

Bone and Stable Isotopes

• 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.

Comparison of Carbon and Nitrogen Isotopes

Molecular Archaeology• Uses genetic material— DNA from

human skeletal remains and living peoples— so geneticists and archaeologists can join forces to create a new approach to reconstructing the past.

Background on DNA• nuclear DNA - Genetic material found

in a cell’s nuclei; responsible for inherited traits.

• Gene - A unit of the chromosomes that controls inheritance of particular traits.

• mitochondrial DNA (mtDNA) - Genetic material found in the mitochondria of cells; inherited only from the mother, mutates at a rate of 2–4% per 1 million years.

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 4400-year-old Egyptian mummy. – This was the first time that anyone

had applied PCR techniques to ancient humans.

Prospecting for Ancient DNA

• 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% mtDNA.– The 0.6% suggests a way to

determine the relatedness among living individuals and groups.

An African Eve • The investigators suggested that all the

genetic composition evident in living human populations could be traced to a single African ancestor.

• Because mtDNA is passed down strictly through the maternal line, this ancestor must have been female.

• She was quickly nicknamed Eve, after the biblical first woman and wife of Adam.

Molecular Clock• Calculations of the time since

divergence of two related populations using the presumed rate of mutation in mtDNA and the genetic differences between the two populations.

Molecular Archaeology• Uses data from living and ancient

peoples to reconstruct population migrations.

• Especially useful is mtDNA and the genetic material in Y chromosomes.

• Although we have much to learn about the rates at which DNA mutates, current studies suggest DNA research will someday be important to reconstructing the past.

Quick Quiz

1. Bioarchaeology is used in the following types of research:

A. Learning the origin and distribution of disease.

B. Reconstructing human diets.C. Analyzing evidence for biological

stress in archaeological populationsD. 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 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:

A. life expectancy at birthB. age profile of a populationC. population migrationsD. A and B only. E. 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.