Emerson and colleagues (2020) provide new isotopic evidence on directly dated human bone from the Greater Cahokia region. They conclude that maize was not adopted in the region prior to AD 900. Placing this result within the larger context of maize histories in northeastern North America, they suggest that evidence from the lower Great Lakes and St. Lawrence River valley for earlier maize is “enigmatic” and “perplexing.” Here, we review that evidence, accumulated over the course of several decades, and question why Emerson and colleagues felt the need to offer opinions on that evidence without providing any new contradictory empirical evidence for the region.

There is no recorded maize (Zea mays spp. mays) from sites predating circa cal AD 800 in the northern Lake Michigan or Lake Superior basins of the western Great Lakes, despite the presence of maize microbotanicals including phytoliths and starches in Michigan, New York, and Quebec as early as 400 cal BC. To evaluate the potential for an earlier maize presence in the northern Lake Michigan basin, samples of carbonized food residues adhering to 16 ceramic vessels were obtained from the Winter site (20DE17) located on the Garden Peninsula in the northern Lake Michigan basin. Each sample was split and sent to two analysts. Both analysts identified low incidences of maize starch and phytoliths in multiple samples, with overlapping identifications on several. Three direct accelerator mass spectrometry dates on the carbonized residues reveal maize incorporated into the residues as early as the second century cal BC, 800 years before any regional macrobotanical evidence. Although the method of dispersal cannot be determined, these results support the proposition that initial northern dispersal of maize in the region may have been nearly 800 years earlier than macrobotanical evidence would suggest and is consistent with the timing of its introduction to the lower Great Lakes area.

Directly dated Cucurbita from archaeological sites near Lake Huron expand the range and human usage of adventive, cultivated wild gourds or squash into the Great Lakes region, USA, by 4000 14C yr BP. The data also show that domesticated C. pepo squash was cultivated there by 3000 14C yr BP. Although milder Hypsithermal climate may have been a contributing factor, squash and gourds expanded northward during the mid-Holocene mainly by human agency and may be the first human-introduced adventive plant in temperate North America. Even after 3000 14C yr BP, when domesticated squash generally replaced wild varieties at northern sites, squash stands were probably informally managed rather than intensively cultivated.

A review of current research reveals multiple lines of evidence suggesting that no single freshwater reservoir offset (FRO) correction can be applied to accelerator mass spectrometer (AMS) ages obtained on carbonized food residue from cooking vessels. Systematically evaluating the regional presence, magnitude, and effects of a freshwater reservoir effect (FRE) is a demonstrably difficult analytic problem given the variation of ancient carbon reservoirs in both space and time within water bodies, and which should be performed in advance of AMS assays. In coastal and estuarine contexts, a priori partitioning FRE from known marine reservoir effects (MRE) is also necessary to eliminate potential mixed effects. Likewise, any FRE varies based on the proportional mix of resources producing the residues and the ancient carbon uptake of those products. Processing techniques are a significant component of assessing potential FRE, and each pot/cooking vessel is therefore an independent context requiring analytic evaluation. In northeastern North America, there is little ethnohistoric/ethnographic evidence for fish boiling/stewing in ceramic cooking vessels; rather, fish were more often dried, smoked, or cooked for immediate consumption on open fires. Assays of fatty acids extracted from prehistoric vessel fabrics even on known fishing sites reveals no evidence for fish in the food mix. These observations suggest that the likelihoods of FRE in carbonized food residue in northeastern North America is therefore low, and that assays potentially suffering from FRO are minimal. In turn, this suggests that AMS ages from carbonized food residues are reliable unless analytically demonstrated otherwise for specific cases, and should take primacy over ages on other associated materials that have historically been employed for critical threshold chronological events.

Ancient carbon reservoirs in freshwater bodies have the potential to introduce ancient carbon into charred cooking residues adhering to pottery wall interiors when aquatic organisms are parts of cooked resource mixes. This ancient carbon results in old apparent ages when these cooking residues are subjected to accelerator mass spectrometry dating, the so-called freshwater reservoir effect (FRE). Roper's (2013) assessment of the FRE on 14C ages from cooking residue in the Central Plains is only the second such peer-reviewed regional assessment in eastern North America. Roper suggests that 13 of 23 14C ages on residue are too old as a result of ancient carbon from fish or leached from shell temper or old carbon introduced via maize nixtamalization. Herein, we re-assess Roper's data set of 14C ages on cooking residues and annual plants and argue that she is mistaken in her assessment of the accuracies of 14C ages from residues. This outcome is placed in the context of the larger FRE literature.

Obtaining radiocarbon assays on objects of chronological interest is always preferable to obtaining assays on spatially associated charcoal. The development of Accelerator Mass Spectrometer (AMS) dating has expanded the number of objects that can be directly assayed because it requires only a few milligrams of material. Pottery can be directly assayed when charred cooking residues adhering to the interior walls are present. The accuracy of AMS ages derived from residues has been questioned in cases where cooking freshwater aquatic organisms may have introduced carbon from ancient carbon reservoirs into residues. Here we provide analytic protocols for examination of this phenomenon and the results of systematic modeling of age estimates on residues formed from fish and maize with varying percentages of dead carbon. We present a regional case study using a large series of AMS age estimates on residues from the Finger Lakes region of northeastern United States to demonstrate how the paleolimnological record and lipid analysis of residues can help to determine if dates on residues from a given region are likely to have been affected by the presence of ancient carbon. In the case of the Finger Lakes, there is no evidence that ancient carbon affected the age estimates.

Analysis of regional site taphonomy that incorporates depositional and postdepositional histories has become increasingly important in understanding the nature of preserved site populations and the strategies necessary for their discovery. We applied a systematic archival and field strategy directed at understanding such taphonomic processes in the coastal sand dunes of the northern and eastern Lake Michigan basin, and coupled these with a tactically directed program of OSL, 14C, and AMS dating. We demonstrate that long-term geological processes including lake level variation, episodic dune activation and stabilization, and the long-term effects of postglacial isostatic adjustments have markedly affected the potential for preservation of sites in coastal dune contexts over time and across subregions of the basin. Preservation potential for different time periods in coastal dunes is largely not synchronous with that of southern Michigan floodplains, posing substantial inferential problems. The archaeology of coastal dunes specifically, and coastal zones generally, must be used with extreme caution when cast against archaeological data from landforms with different formation processes and histories. While particularly true for the Great Lakes region, these results have implications for regional research broadly.

The histories of maize utilization in eastern North America have been substantially revised recently, primarily because of the analysis of charred cooking residues encrusted on pottery. A multifaceted research strategy of bulk δ13C assays coupled with accelerator mass spectrometry radiocarbon data and microbotanical evidence can yield coherent regional maize use histories. Bulk δ13 C assay interpretation complications include (1) variations among vessels by site, (2) a potential for false negatives, and (3) a wide range of variation potentially present for any given time period. Regional histories using this approach can be quite variable without appropriate use of multiple lines of evidence.

Fischer and Heinemeier (2003) present a hypothesis that the freshwater reservoir effect produces old apparent ages for radiocarbon dates run on charred cooking residues in regions where fossil carbon is present in groundwater. The hypothesis is based in part on their analysis of dates on charred cooking residues from 3 inland archaeological sites in Denmark in relation to contextual dates from those sites on other materials. A critical assessment of the dates from these sites suggests that rather than a pattern of old apparent dates, there is a single outlying date—not sufficient evidence on which to build a case for the freshwater reservoir effect.

Concepts of residential and logistic mobility are applied to survey assemblages from multiple decades of research along the interior drainages of central lower Michigan. Drawing on the ethnographic record of boreal hunter-gatherers and archaeological interpretations of long-distance logistic mobility from the Mesolithic of northern England and continental Europe, it is argued that the importance of logistic mobility is underrepresented in summaries of northern hemisphere hunter-gatherers. Reconstruction of Middle Holocene environments suggests that the resource structure of the central Michigan uplands was one that fostered use of logistic mobility, and that interior Middle Archaic assemblages and site structures reveal special function activities systemically tied to residential and other special function sites at lower coastal elevations, as well as currently submerged under Lake Huron. We conclude that rising levels of Lake Huron ca. 4500 B.P. resulted in decreased land area, population packing, and a consequent shift to residential mobility by the Late Archaic. Further, the results of this analysis can serve as a comparative framework for recognizing the role of logistic mobility in the evolution of hunter-gatherer adaptive strategies in other regions.

The Schultz site (20SA2) is a benchmark site for understanding the Woodland adaptations of the Upper Great Lakes, although its older excavation data is not comparable with recent Eastern Woodlands research, which consistently uses fine-grained recovery techniques. The 1991 Schultz-site research collected supplementary and upgraded subsistence and environmental data to address questions about regional transformations from hunting and gathering to horticulture. In addition, questions regarding the role of aquatic and wetland resources, and how environmental change affected the availability and productivity of these alternative resources, were addressed. Results of faunal, floral, and geoarchaeological research reveal that Woodland economies in the Saginaw region of the Upper Great Lakes were keyed to environmental changes affecting wetland availability and productivity. The Early Woodland presence of cucurbits does not appear economically important until later when it is combined with more reliable supplementary food sources. Although chenopod is present during the Middle Woodland and early Late Woodland, wetland plant and animal resources act as surrogates for other starchy and oily seeded annuals common in other portions of the Midwest and in the Mid-South. Maize apparently does not achieve economic significance until the Late Woodland period. A model of this combined northern and southern strategy is developed.

The needs of new analytic techniques that may be depleting or destructive, or which have requirements that may be at odds with other approaches, place new and different demands on curated archaeological research collections. Curatorial approaches and attitudes need to accomodate such changes in research environment and be aware of both the potentials of curated collections as well possible conflicts. A pilot study employing AMS dating of adhering residues on a curated ceramic collection is used to illustrate curatorial concerns and decisions associated with the use of modern techniques. It is argued that continued use of such collections is important, and that management decisions must keep pace with technological innovations.

Problems involved in the application of probability sampling strategies to woodland environments are discussed and illustrated by example. The results of the sample and the field tactics employed in its implementation are appraised. Some directions for the development of specialized field tactics in woodland environments, including the reduction of transect intervals, the use of test-pitting, and the generation of explicit means for survey strategy alteration, are suggested.