|
Stable isotope analysis can be used to investigate
the dietary patterns of ancient human populations. The stable isotope
of carbon (C13) varies in more common species of C3 plants and the
tropical grasses of C4 plants due to differing photosynthetic pathways.
Carbon isotope ratios such as C13/C12 signal changes in human diet
that vary depending on the amounts of C3 and C4 plants consumed.
Carbon isotope analysis has tracked the agricultural expansion and
domestication of the C4 plant such as maize in the Americas and
sorghum use in Africa. Isotopes of carbon and nitrogen can be used
to investigate dietary changes and weaning in prehistory. Changes
in nitrogen isotope that reflect the protein from breast milk occur
at weaning and changes in carbon isotopes from weaning food should
be evident. Rib samples (N=15) from a Christian Nubian population
aged from birth to year five from the site of Kulubnarti (550-750
AD) were used to determine the onset and duration of weaning. Depending
on rib size, approximately 0.2-0.9 grams were powdered from each
bone and dissolved in a low concentration (0.1M) of HCL to precipitate
out the organic collagen matter to be analyzed for presence of nitrogen.
The age of weaning can be determined by the significantly lower
levels of nitrogen expected as the children are weaned. Weaning
is an important public health issue since it is a period of risk
for malnutrition, infections, and mortality. Health of past populations
allows us to gain an evolutionary perspective that can be applied
to present contemporary populations.
In infant nutrition, there exists an ongoing debate
regarding the superiority of breast milk vs. powder supplementation,
as well as the age at which children should be weaned. Studying
the weaning patterns of ancient populations allows us to gain an
evolutionary perspective applicable to modern populationsWeaning
is a complex process, involving two major steps: the introduction
of supplement foods such as coarse cereals 2) the cessation of breast
milk consumption In many countries, a contaminated water supply
and weaning foods deficient in iron or other nutrients poses a risk
for malnutrition, infections and mortality to infants due to their
underdeveloped immune systems.
The materials were from a site excavation from the
1960's. Ancient Nubia was located along the Nile River, on the current
border of Egypt and the Sudan The Kulubnarti site is located in
an area known as Batn el Hajar, “Belly of the Rock,”
whose hot, arid conditions allowed for excellent preservation of
remains (see map) This cemetery population represents one of the
last remaining Christian groups in Nubia Rib samples (N=15) from
Nubian population aged birth to year five Rib section taken and
depending on rib size approximately 0.2-0.9 grams were powdered
from each bone Treated in low concentration (0.1M) for three weeks
to remove the mineral matrix and isolate the organic collagen matter
Samples to be shipped for light stable isotope mass spectrometry
reading.
Results are pending from a mass spectrometry reading
lab.
This study will be an added resource to already existing
information on Ancient Nubian populations It will give us an insight
into the affects political, agricultural and economical circumstances
have on diet such as changes in the age of weaning In the modern
age, with the advent of agriculture, the age of weaning has become
earlier, and alternatives to breastfeeding by way of supplementary
foods.
Howard Hughes Medical Institute Grant No. 52003071
Dennis P. van Gerven for the nubian samples.
This study investigated the age at weaning in an
ancient nubian population. Since the advent of agriculture and thus
a increase in the availability of weaning foods, the weaning age
has become earlier. Weaning is an issue important to child nutrition
because of the debate over when to wean and when to supplement infants.
|
