The Climate, Corn, and Culture Change project was born out of an investigation of the earliest farming communities in the Middle Ohio Valley. These Fort Ancient societies are well known in the region, but their inception has long been explained away through processes of gradual development because of a lack of well excavated early sites. In his book on SunWatch, a middle Fort Ancient site occupied between AD 1300-1500, Cook identified distinct Mississippian connections but hypothesized that the lower Great and Little Miami Valleys, which have seen comparatively little work, reflected potential areas of Mississippian contact.
With this limitation in mind, Cook developed a large-scale, systematic project to examine in detail Fort Ancient sites in the Great and Little Miami River Valleys of southwest Ohio and southeast Indiana. The Fort Ancient Regional Movement (FARM) project examined archaeological and biological evidence focused on the movement of people and the establishment and persistence of village life.
In his 2017 PhD dissertation, Comstock examined spatial and temporal patterning in paleoclimate data. Using the Palmer Drought Severity Index, a modeled proxy for moisture availability in the past, he identified two key patterns. First, although Mississippian centers developed in a brief window of wet conditions, they were almost immediately faced with multi-decadal droughts. This work built on that of Larry Benson and others who specifically examined Cahokia in the context of such climate perturbations. The second pattern that Comstock identified relates to the Middle Ohio Valley.
Above images reflect drought and moisture availability from AD 1050 to AD 1300 in 25-year time periods. (Comstock and Cook in press).
While the Mississippian heartland was affected by droughts, the Middle Ohio Valley beyond the Falls of the Ohio (near modern Louisville) experienced approximately 300 years of conditions that were as wet as or wetter than modern times. This period between AD 1000-1300 reflects an important window that saw the influx of Mississippian migrants into the Middle Ohio Valley. These immigrants had left Mississippian centers, many of which experiences ecological and social stress, and founded egalitarian villages in a region lacking significant environmental pressures.
Corn (Zea mays) was originally domesticated in central Mexico, and through complex processes of diffusion, trade, and migration, came to form the foundation of Late Prehistoric (post-AD 1000) subsistence systems throughout much of North America. The mechanisms behind this transition are only superficially understood, and likely vary from region to region. Although it was present in small amounts in preceding Late Woodland groups, Greenlee’s regional examination of carbon isotopes in human remains suggests that corn was not a significant part of subsistence systems at this time. Conversely, corn represented a large proportion of the diet for Fort Ancient societies.
Directly dated corn remains from sites within the Middle Ohio Valley suggest initial variation in species, followed by more consistency. Turpin, which has a Late Woodland component, produced evidence of 8-row, 10-row, and 12-row variants during the Late Woodland period. After AD 1000, the majority of cobs and kernels recovered from sites reflect the Northern 8-row variety.
Maize, as a fundamental element of the Fort Ancient lifestyle, needs to be more fully understood as its incorporation into prehistoric lifestyles intersects with ideas of migration, climate change, and cultural hybridity.
Above figures: maize in prehistoric diets in the Middle Ohio Valley as evidence by carbon isotopes (left). Dated maize as part of the FARM project (right).