23 Aug 2009, 10:24am
Cultivated Landscapes
by admin

Initial formation of an indigenous crop complex in eastern North America at 3800 B.P.

Bruce D. Smith and Richard A. Yarnell. 2009. Initial formation of an indigenous crop complex in eastern North America at 3800 B.P. Proceedings of the National Academy of Sciences, Vol. 106 No. 16 pp 6561–6566.

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Although geneticists and archaeologists continue to make progress world-wide in documenting the time and place of the initial domestication of a growing number of plants and animals, far less is known regarding the critically important context of coalescence of various species into distinctive sets or complexes of domesticates in each of the world’s 10 or more independent centers of agricultural origin. In this article, the initial emergence of a crop complex is described for one of the best-documented of these independent centers, eastern North America (ENA). Before 4000 B.P. there is no indication of a crop complex in ENA, only isolated evidence for single indigenous domesticate species. By 3800 B.P., however, at least 5 domesticated seed-bearing plants formed a coherent complex in the river valley corridors of ENA. Accelerator mass spectrometer radiocarbon dates and reanalysis of archaeobotanical assemblages from a short occupation of the Riverton Site in Illinois documents the contemporary cultivation at 3800 B.P. of domesticated bottle gourd (Lagenaria siceraria), marshelder (Iva annua var. macrocarpa), sunflower (Helianthus annuus var. macrocarpus), and 2 cultivated varieties of chenopod (Chenopodium berlandieri), as well as the possible cultivation of Cucurbita pepo squash and little barley (Hordeum pusillum). Rather than marking either an abrupt developmental break or a necessary response to population-packing or compressed resource catchments, the coalescence of an initial crop complex in ENA appears to reflect an integrated expansion and enhancement of preexisting hunting and gathering economies that took place within a context of stable long-term adaptation to resource-rich river valley settings.


Marking a major evolutionary episode in human history, the transition from hunting and gathering to agricultural economies spanned several millennia and occurred independently in 10 or more different world regions, including eastern North America (ENA) (1) (Fig. 1). In each of these independent centers, this long transition began with the initial domestication of a number of indigenous wild progenitor species. These different domesticates eventually were coalesced to form regionally distinctive complexes of domesticates and low-level food production economies. As a result of parallel and often cross-illuminating efforts by geneticists and archaeologists over the past several decades, we are gaining a much clearer idea of where and when domestication of different individual species of plants and animals occurred (3, 4). Much less is currently known, however, about the equally important process that led to numbers of different species being brought together to form coherent distinctive domesticate complexes in different world regions. When did such domesticate complexes initially develop? What was the identity and relative importance of each complex’s different constituent species? What can be said regarding the environmental and cultural context of coalescence of these early domesticate complexes in different world regions, and what can be said about the societies that developed them? Combining extant information with new data, this article addresses these key questions and provides a clear picture of the initial emergence of a crop complex in one of the world’s best-documented independent centers of domestication — the eastern woodlands of North America.

The Temporal and Spatial Context of Initial Plant Domestication in ENA

Based on several morphological changes associated with the adaptive syndrome of domestication that have been documented in seed specimens recovered from 4 Late Archaic period archaeological sites in the Oak-Savannah and Oak-Hickory forest regions of ENA (i.e., seed size increase and reduction in seed-coat thickness), at least 4 indigenous seed-bearing plants were brought under domestication in the region over a span of ~1,200 years from 5000 to 3800 B.P. These plants include squash (Cucurbita pepo ssp. ovifera), sunflower (Helianthus annuus var. macrocarpus), marshelder (Iva annua var. macrocarpa), and chenopod (Chenopodium berlandieri) (1). Maize (Zea mays), the first Mesoamerican domesticate to reach ENA, did not arrive for another 1,500 years, at ~200 B.C. (see SI Text). In addition to these 4 species that exhibit morphological changes because of domestication, 3 other eastern seed plants that lack such changes have also been identified, based on their abundance in seed assemblages before 2000 B.P., as likely crops and as the subjects of deliberate planting and harvesting of stored seed stock. These plants include erect knotweed (Polygonum erectum), little barley (Hordeum pusillum), and maygrass (Phalaris caroliniana). …

The Riverton Site and an Initial Crop Complex

In his landmark study of the Late Archaic Riverton culture, Howard Winters excavated 3 large shell midden sites (Robeson Hills, Swan Island, and Riverton) located along a 20-mi stretch of the Wabash River in southeastern Illinois (12). …

Roughly rectangular in shape, the Riverton clay floors were ~100–200 ft2 in size and from 4 to 6 inches in depth. Like similar features documented in Late Archaic period contexts across the eastern woodlands (13, 14), these clay floors are thought to be prepared house platforms. …

In many respects, the Riverton plant assemblage reflects a general pattern of reliance on certain plant species and groups of species that extended over a broad geographical area during the Late Archaic period. Nut-bearing trees, for example, were an important food resource across much of the Oak-Savannah and Oak-Hickory forest regions during the Late Archaic period (9, 16–20), and the Riverton plant assemblage is dominated by nutshells from a variety of tree species, including walnut (Juglans nigra and Juglans cinerea), hickory (Carya sections Carya and Apocarya), hazelnut (Corylus cornuta and Corylus americana), and oak (Quercus sp.) (15). …

In addition to the 2 definite domesticates (sunflower and bottle gourd) and the 2 possible cultivated species (squash and little barley) identified by Yarnell (15), recent reanalysis of the Riverton assemblage has also documented the presence of several additional domesticated seed plants: marshelder (I. annua var. macrocarpa) and chenopod (C. berlandieri). … The C. berlandieri specimens from Riverton, in contrast, represent the earliest record for this domesticate in the East, and 2 distinct cultivated varieties are present, along with a likely companion weed. …

The Developmental Context of an Initial Crop Complex

As a result of both an unusual context of preservation of uncarbonized plant remains and the careful recovery and analysis of multiple archaeobotanical samples (15), the Riverton site provides a rare view of the development of an initial crop complex in ENA. In contrast to earlier sites that yielded evidence of only a single indigenous domesticate from a single context (i.e., Phillips Spring, Napoleon Hollow, and Hayes), Riverton provides evidence for the contemporaneous cultivation of least 5 domesticated seed crops: thin-testa and pale-seeded chenopod, bottle gourd, marshelder, and sunflower. In addition, domesticated C. pepo squash and cultivated little barley may also have been present. …

In addition to documenting the sustained importance of chenopod, several of these Late Archaic/Early Woodland period sites also provide evidence for the subsequent broad geographical extent and consistent species composition of the initial crop complex documented at Riverton. Excavation of the Marble Bluff Shelter, a small, seasonally occupied site in the Ozarks (Fig. 1), uncovered a rear-wall storage crevice containing twined bags of seeds of domesticated thin-testa chenopod, marshelder, sunflower, and squash dating to ~3400 B.P (27, 29, 30). Similarly, a rock-lined storage pit (Feature 71) excavated at the Cloudsplitter Rockshelter in eastern Kentucky (Fig. 1) and dating to ~2800 B.P. contained 7 L of seeds, primarily from domesticated crop plants: thin-testa and pale chenopod, marshelder, sunflower, and squash (28, 33, 34).

In addition to offering the earliest (3800 B.P.) clear evidence for the formation and composition of a chenopod-centered group of domesticates in ENA, the Riverton site also offers insights, at the scale of an individual society, into the larger environmental and cultural contexts within which an initial crop complex was created. Like other contemporary Late Archaic river valley settlements of the Oak-Savannah and Oak-Hickory forest regions of the East, Riverton was occupied by a small-scale society consisting of perhaps a half-dozen related extended family units. …

The subsistence economies of these small-scale Late Archaic societies remained remarkably stable over several millennia, reflecting sustained and successful long-term adaptations to the resource-rich river valley corridors of the Oak-Savannah and Oak-Hickory Forest Regions of the East. Settlements like Riverton yield evidence of utilization of a wide range of aquatic resources including fish, bivalves, and snails, and the white-tailed deer (Odocoileus virginianus) consistently is the most important terrestrial prey, followed by lesser reliance on a suite of smaller species (e.g., turkey, raccoon, rabbits, and squirrels) (19, 37). The nuts of hickory, walnut, and oak species invariably dominate the plant assemblages of these river valley settlements as they do at Riverton (15), with low seed-to-nut ratios reflecting a lesser reliance on the seeds of wild annual seed-bearing plants (9, 16, 17–18). …

Rather than provide support for explanatory frameworks that rely on external environmental stress, population growth, landscape-packing, constricted resource zones, and carrying capacity imbalance in explaining the initial domestication of plants and animals and the subsequent coalescence of domesticate complexes, Riverton and ENA suggest an oppositional conclusion. The initial domestication of local seed plants and the subsequent formation of a crop complex does not appear to have occurred in response to any carrying-capacity challenges or seriously compressed and compromised resource catchment areas. Rather, this domestication seems to have taken place within a context of stable, long-term adaptations to resource-rich environmental settings. In addition, the initial coalescence of these domesticate complexes and the associated emergence of low-level food production economies do not appear initially to have marked an abrupt developmental break; rather, they appear to have represented an integrated additive expansion and enhancement of preexisting hunting and gathering economies (17). As the temporal, environmental, and cultural contexts of the initial coalescence of domesticate complexes come into clearer focus in other regions of the world, it will be interesting to see to what extent this major transition parallels what we now know about ENA.

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