A publication of the Archaeological Institute of America
New dates on crop remains are transforming our understanding of the history of maize-bean-squash agriculture in the northeastern United States. For many years it was thought that the three plants were adopted at the same time or in quick succession, becoming established between A.D. 1000 and 1100, but it now appears that the three crops were adopted over a 2,100-year period.
The old belief was based largely on the work of former New York State Museum archaeologist William A. Ritchie at the Roundtop Site in the Susquehanna River Valley of New York. In 1969 and 1973 publications, Ritchie linked charred maize, beans, and squash remains found in a pit feature at Roundtop with a radiocarbon date of A.D. 1070 obtained on wood charcoal from another pit feature that contained no crop remains. While the earliest dates associated with maize in the Northeast now range between A.D. 750 in eastern Pennsylvania and A.D. 900 in southern New England, Ritchie's date has been the earliest for beans and squash until recently.
In 1997 domesticated squash rind fragments from the Memorial Park Site in the valley of the West Branch of the Susquehanna River in north-central Pennsylvania yielded an 800 B.C. radiocarbon determination using accelerator mass spectrometry (AMS) dating (published that year by myself and Nancy Asch Sidell, an archaeobotanical consultant in Orono, Maine, in the July issue of American Antiquity). The oldest reported date for a domesticated crop in the Northeast, it clearly indicates that this component of the maize-bean-squash complex had a much longer history in the region than was previously thought.
New AMS dates (just published by myself in the New York State Museum Bulletin [no. 494] and with C. Margaret Scarry of the University of North Carolina at Chapel Hill in American Antiquity [October 1999]) show that beans from the Roundtop Site were, in fact, from about A.D. 1300 at the earliest. Dates on beans from four additional sites in Vermont, New York, and Pennsylvania, all proved to be close to, or later than, A.D. 1300. These dates strongly suggest that beans were established in the Northeast two centuries later than previously thought.
The results also indicate that maize-bean-squash agriculture developed gradually as the three crops were adopted independently over a period of at least some 2,100 years and they were grown together regularly in some locations beginning only around A.D. 1300. This is consistent with the sequence of adoption of maize, beans, and squash elsewhere in the eastern U.S. although in each case the crops were adopted later in the Northeast. In the Midwest, the oldest date for indigenously domesticated squash is around 2350 B.C., while the earliest date on maize is 170 B.C., and A.D. 1000 to 1200 for beans.
The new dates for the Northeast show that the adoption of the three crops did not result in a sudden transformation of subsistence systems at around A.D. 1000. Rather, as in other areas of the eastern U.S., the development of maize-beans-squash agriculture occurred gradually as each crop diffused east- and northward, adapted to new environments through natural selection or became locally extinct, competed and established co-evolutionary relationships with other crops, and established symbiotic relationships with human populations.
The adoption and subsequent evolution of maize-beans-squash agriculture in the Northeast, then, was not a simple affair. The stage is now set for additional research that will lead to better understanding of the regional variation in crop adoption and agricultural evolution in the northeastern U.S.
John P. Hart is with the New York State Museum.