| The Upper Mississippi River Valley in west-central Illinois is little known archaeologically, but is an area which may be of great interest for prehistoric human diet in the Eastern Woodlands culture area of North America. Carbon and nitrogen stable isotopes of human bone collagen were analyzed from Lawrence Gay, Joe Gay, Yokem, Knight, and Schild. Although maize does not generally become popular until the late Late Woodland, the cluster here of early Late Woodland archaeobotanical finds of maize is corroborated by carbon isotopes. Substantial maize consumption is apparent at Joe Gay and Knight, and Koster Mounds in the neighboring Lower Illinois Valley. The Knight early Late Woodland component may date as early as AD 400. The distribution of carbon isotope ratios is bi-modal: fluoride relative dating plus the age distribution of maize consumers suggest maize became popular very fast, too fast for conventional archaeological techniques to record. Nitrogen isotopes were always more enriched in Mississippi Valley sites than Lower Illinois Valley sites previously analyzed, probably the result of the wider floodplain in the Mississippi providing more aquatic foodstuffs.; No status differences in diet were recorded between Middle Woodland Joe Gay and Lawrence Gay. At all sites and time periods, males had more enriched nitrogen isotope ratios than females, a pattern known from other studies. The cause is unknown, but could be related to raised urea nitrogen levels recorded in modern males. Older individuals at several sites had more enriched nitrogen isotope ratios than their juniors; this may possibly be linked to osteoporosis which increases urea nitrogen excretion. |
