What types of food did this individual eat, and did she die from a disease or trauma? Skeletal remains offer anthropologists a view into not only how a person died but also how they lived. As science and technology advance, we have more tools at our disposal to examine human remains and learn about individuals, societies, and cultures. Over the last few weeks, I’ve discussed what an anthropologist can learn from skeletal remains, including whether the skeleton is male or female, the race and height of the individual, and the age of the victim when he or she died. This week we will consider how this person lived and died.
Recent excavations at the Jamestown colony in Virginia gave anthropologists a glimpse into the harsh winter of 1609-1610 when the colony ran out of food, and only sixty out of five-hundred colonists survived. Gravediggers couldn’t keep up with the ever-growing pile of bodies and ended up placing two or three at a time in a single grave. Skeletal remains provided evidence of starvation, and tool marks found on some skeletons suggested other colonists had carved and eaten their flesh. While stories passed down through the ages from Jamestown have mentioned incidents of cannibalism, the skeletal remains produced the first confirmation.
Diet
Isotope Analysis has given us some of the most interesting information about what our ancestors ate and how they moved in relation to their resources. Most people know about radiocarbon dating or C-14 analysis. C-14 is an unstable isotope of carbon, and it deteriorates at a known, predictable rate. By measuring the amount of C-14 in old bones, scientists can estimate the age of the bones.
In contrast to C-14, Carbon-13, Nitrogen-15, Oxygen-18, Strontium-86, and Strontium-87 are all stable isotopes, and they do not decay over time but remain constant. The ratios of these isotopes vary in different foods and in the environment, and depending upon what we eat and where we live, our bones incorporate these compounds in different amounts and form a record of our lives. Scientists call this our isotopic signature. Isotopic signatures offer archaeologists a way to learn about the environment at a particular time and place and to understand the factors that influenced the way a community developed. A direct relationship exists between the diet of an individual and the isotopic signature in his bone collagen. Did he eat grasses, fruits, meat, or fish and shellfish?
The study of isotopes also provides researchers with information about mobility and migration of past cultures and individuals. Humans move for many reasons, including the search for more plentiful food, to find a suitable mate, for warfare, and for trade. Strontium and Oxygen isotopes are used to reconstruct past movements of an individual. If a person lived his life in the general area where he died, then the isotopes in his bone collagen will match the isotopes in the environment where he was found. Local isotopes are measured from the substrate, groundwater, and precipitation of a place. If his bone and teeth enamel isotopes differ from the local environmental isotopes, then the archaeologist knows the individual traveled to this region from somewhere else.
Disease
Bones display evidence of many diseases and trauma. Healed fractures, even ones which are several years old, often leave marks on bones. In osteoarthritis, the bones rub together, creating eroded and polished bones. Rheumatoid arthritis causes swollen joints which can push against and deform bones. Ankylosing spondylitis produces an inflamed spine which leaves characteristic markers on the vertebrae. Gout causes increased uric acid in the blood which can crystallize in the joints and cause an erosion of the joint surfaces. Cancers can affect a skeleton in two ways. Cancers in the soft tissue next to a bone create pressure on the bone, often causing lesions or holes in the bone. Cancers producing tumors directly in the bones cause skeletal changes which can be seen long after the soft tissue has decomposed.
Infectious diseases can also leave a trace on bones. Tuberculosis causes lesions in the bones, especially the ribs, spine, and pelvic bones. Syphilis, a sexually transmitted bacterial disease, forms degenerative pits on the surface of the bone and is especially severe on the forehead, nose, and shin.
As DNA research progresses and Methods of DNA sequencing become more affordable, we will learn much more about the diseases an individual suffered from studying his bones. Chromosomal abnormalities have been identified in DNA extracted in human bones 7400 years old, but scientists believe non-human DNA will be the most useful in identifying the importance of diseases such as malaria, cholera, and the plague in ancient communities.
Malnutrition and Starvation
Malnutrition and starvation lead to decreased bone mineral density. Long term malnutrition causes stunted growth and an increased risk of bone fractures. Oddly, bone marrow adipose tissue (BMAT), a type of fat, increases during starvation while other types of adipose tissue decrease. Scientists are uncertain why BMAT increases when a person is starving to death, but they believe BMAT is either a passive filler occupying spaces left by dying bone cells, a consequence of suppressed bone formation, or an adaptation for surviving starvation.
Next week, I will post an excerpt from my upcoming novel, Karluk Bones, and you can read how a young anthropology student explains her analysis of human bones found near Karluk Lake on Kodiak Island.
Be sure to sign up for my free mystery newsletter, and I’ll see you back here next week.
Robin Barefield is the author of three Alaska wilderness mystery novels, Big Game, Murder Over Kodiak, and The Fisherman’s Daughter. To download a free copy of one of her novels, watch her webinar about how she became an author and why she writes Alaska wilderness mysteries. Also, sign up below to subscribe to her free, monthly newsletter on true murder and mystery in Alaska.
