Tuesday, April 24, 2012

Human Remains - The Northwest Coast

Chisholm, Brian S., D. Erie Nelson, and Henry P. Schwarcz
1983 Marine and Terrestrial Protein in Prehistoric in Prehistoric Diets on the British Columbia Coast. Current Anthropology 24.3:396-398

This article focuses on explaining how stable-carbon isotope ratios, which are collected from human bone collagen, can tell us whether an individual relied mostly upon a marine protein based diet, or a terrestrial protein based diet. The researchers took data from a total of 48 individuals from various sites along the British Columbian Coast, and interior.
Prior to the development of stable-isotope analysis, the only data that researchers could use to base their conclusions off of were from the ethnographic and archaeological descriptions of subsistence. These descriptions are usually incomplete or imprecise, making it difficult to draw any solid conclusions on the actual degree of the dietary reliance of the prehistoric Northwest Coast people upon marine species. Stable-isotope analysis is a way to directly test an individual to determine the average relative amounts of terrestrial and marine proteins in the diets of these prehistoric people.
The original percentage of dietary reliance upon marine life, based solely off of the ethnographic and archaeological records, was estimated to be around 45-55%. The results that the researchers received from the stable-isotope analysis, gave them an estimate of around 90% reliance upon marine life, and definitely not lower than 85%. It is very obvious that these two methods for collecting data produce very different results, as well as the stable-isotopic results being much more accurate due to the direct testing of the bones, rather than basing an estimate off of incomplete literature.
The individuals tested all came from various sites along the British Columbian Coast, and many of these individuals ranged in dates as well; all the individuals ranged from approximately 5,000 years ago, up until about 70 years ago. This range of dates was used so as to see if there were any significant changes in diet overtime, after the switch to specializing/intensifying marine life diets. This test suggested that there was little, if any, changes over this time period of about 5,000 years; which makes sense when you consider how rich the marine resources are along the Northwest Coast.
This article proves that stable-isotopic analysis will continue to be a helpful tool for the field, especially when trying to draw conclusions about the typical diet for a society or region.

Lazenby, Richard A. and Peter McCormack
1985 Salmon and Malnutrition on the Northwest Coast. Current Anthropology. 26.3:379-384

This article examines the possibility of a link between prehistoric Northwest Coast societies and their level of dependence on salmon and other marine animals for subsistence, with malnutrition, possibly linked to hypervitaminosis D (an over abundance of vitamin D in the body). In their research, they analyzed different groups of human remains from several different sites, and looked at the differences in their C13 signatures, by using stable-isotopic analysis. Depending on what an individual’s C13 levels look like, we can determine how important salmon and other marine animals were to their diets, as well as estimates on how much was most likely consumed on a daily basis. Once we know how much salmon and other similar marine life was consumed on a daily basis, we can therefore determine more clearly, whether these people may have suffered from hypervitaminosis D, due to eating too much fish, or not.
It is determined that the average amount of salmon consumed daily by an average adult, would be between 1.5 and 3kg (approximately one half of a fish to a whole fish consumed daily by each adult). The amount estimated for an average child between the ages of 4 to 10 years, would be approximately half the serving of an adult; approximately .75 to 1.5kg. However, the estimate for children is less accurate, due to the fact that we do not know if salmon was as important to a child’s diet as it was to an adult’s, as well as several other factors that make it difficult to make a clearer estimation.
Hypervitaminosis D is caused when the body consumes too much Vitamin D. While is may take a substantial amount over the recommended daily dose to effect an adult, even very small overdoses can affect children. Because the amount of Vitamin D consumed, directly relates to how Calcium is processed in the body, when Vitamin D foods are consumed alongside calcium rich foods, often the symptoms of Hypervitaminosis D (hypercalcemia) can become more severe. These symptoms affect the gastrointestinal tract, and can cause neural and psychic problems. As soon as the over consumption of Vitamin D ceases though, the symptoms will also stop fairly quickly; usually within a few days.
The researchers discuss how it is possible that these early societies may have noticed a correlation between these symptoms and the consumption of salmon, especially in children who are more vulnerable. If these early societies did make this connection early on is the intensification period, it would explain why many, children of this area appear to have eaten substantially less salmon than the adults, and most likely supplemented salmon diets with terrestrial plants and animals.

1 comment:

  1. The article by Chrisholm and colleagues is interesting. It relates a lot to one of the annotated bibliographies I did for this region. The article I wrote about was by Madonna L. Moss. She looked at the importance shellfish had, or marine life, in the diets and lives of past societies along the Northwest Coast. She looked specifically at the Tlingit and had that shellfish not only had a major role in subsistence, as the results showed in the article by Chrisholm and colleagues, shellfish also had a symbolic significance. Because shellfish was so easily accessible, Moss says that people viewed others who ate shellfish as lazy. Thus, there was a slight stigma attached to those who ate shellfish. This stigma seemed to matter much more for men, because masculinity was defined by the ability to hunt and fish. Relying on shellfish went against this view of what is masculine and manly. Moss goes on to say that in times of need, only then was it acceptable for men to eat shellfish. However, shellfish played a large role within their diets, again, like the article by Chrisholm and colleagues showed. Moreover, shellfish was mainly collected by women.

    Moss, Madonna L. 1993. Shellfish, Gender, and Status on the Northwest Coast: Reconciling Archaeological, Ethnographic, and Ethnohistorical Records of the Tlingit. American Anthropologist 95(3): 631-652.