The
objective of this thesis was to reconstruct the living conditions and
particularly the nutrition base of an urban and a rural medieval population in Brandenburg, Germany
and one population near the sea in Mecklenburg-Vorpommern,
Germany. The goal
was to comprehend the staple
diet as well as the basic quality of the food. The
history of human population is tightly interrelated to temporal changes of the
inhabited ecosystems. The natural or anthropogenic changes of the environment
cause changes in human behaviour and lead to the development of various
adaptive strategies of adaptation. Especially the search for resources has
elicited man to alter his environment. As such an investigation was lacking
until now, femoral and rib samples of about 20 adult individuals and 15 - 21
children of each population as well as animal bones were taken and prepared for
the analysis of trace elements and
stable isotopes. 15 trace elements (As, Cd,
Co, Pb, Ni, Cu, Al, Sr, Zn, Mg, Fe, Mn, Ca and P) and the stable isotopes of
carbon, nitrogen and oxygen were analysed. The comparison of the rural und
urban populations allowed to find qualitative and quantitative differences in
the diet and to trace environmental impacts. More features were found to
differentiate between social groups, both sexes and different age groups.
Another focus of this research was the weaning age of children and the stress
caused by heavy metals.
Collagen is
well suited for the analysis of stable isotopes. It can maintain its molecular
structure for thousands of years after the individual’s death and is resistant
for post-mortem changes. In a living organism the collagenous material will be
completely renewed every 10 to 30 years. Based on this fact, it is possible to
draw conclusions on dietary customs of an individual living a long time ago.
This is possible using the stable isotopes analysis of nitrogen and carbon.
Collagen
represents mainly one fraction of protein in food. The main part of nitrogen is
taking up with the daily food. The proteins of single individuals possess similar
d15N values.
As a result
of the “trophic level effect” where consumer tissue d15N
values are elevated by approximately 3 - 4 ‰
over dietary protein, breastfeeding children have tissue d15N values 2 - 3 ‰
higher than their mothers. During the weaning process, the consumption of
supplementary foods results in a decline in infant d15N values. When a child is fully weaned its
protein d15N values are nearly identical to those of its
mother, indicating similar diets.
The hydroxylapatite
of mineralized tissues contains about 2 - 4 % carbonat (CO32-).
The d13C in carbonate varies with that in an
individual`s diet, the offset between diet and carbonate values being about 9 - 10 ‰.
For an adult skeleton, a complete replacement cycle takes about 7 - 10
years. Carbonate d13C reflects the carbon stable isotope values in
whole diet not just in proteins.
In the
mineral fraction of bones and teeth, oxygen is present both in carbonate and
phosphate. Oxygen isotope ratios (d18O) in meteoric water varies with climate, and
in most regions a firm relationship exists between d18O and temperature, lower temperatures causing a
lower d.Oxygen isotope values in body are, for most
larger mammals, directly related to their drinking water.
According
to this analysis in Bernau weaning happened at the age of about two. In the village of Tasdorf weaning occured a little later,
at the age of two-and-a-half year and in Usedom it was the longest weaning
process: children were breastfeeding up to and above the age of three years.
The
distribution of the fractions of stable carbon and nitrogen in the village of Tasdorf suggests a high portion of
vegetable food, whereas the nutrition base of the urban environment in Bernau
offered a higher proportion of meat-consumption. Interestingly, the women of
Tasdorf showed a lower d15N value compared to the men, suggesting that
the men in Tasdorf consumed more meat than their wives.
In Usedom,
the d18O values indicate to a colder climate than in
Bernau or Tasdorf, and astonishingly, in the island town Usedom marine protein
can be ruled out as a major source of nutrition.
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