Ancient farming in eastern North AmericaT. Douglas Price1

Laboratory for Archaeological Chemistry, University of Wisconsin, 1180 Observatory Drive, Madison WI 53706; and Department ofArchaeology, University of Aberdeen, Aberdeen AB24 3FX, Scotland

Answers to one of the great ar-chaeological questions arechanging. The origins of agri-culture have been a center-

piece of research for many years.Specific what, where, and when ques-tions are being resolved. Recent yearshave seen an extraordinary burst of newinformation about this fascinating sub-ject (1–3). Today, there are at least 10recognized regions in the world wheredifferent species of plants and animalswere first domesticated (Fig. 1). Varioustheories have arisen over the last cen-tury and a half to explain how and whythis happened, but no consensus hasemerged. A variety of causal factorshave been explored as potential driversfor domestication: climate change, car-bon dioxide increases, populationgrowth, developments in human cogni-tion, ideology, and increasing socialcomplexity and differentiation (4–8).New information from the easternUnited States in the article by Smithand Yarnell in this issue of PNAS (9)provides much food for thought.

Advances in our knowledge about thefirst farmers are caused in large part bynew technology and development. Ac-celerator mass spectrometry (AMS)radiocarbon dating permits the measure-ment of very small samples and now hasbeen used to directly date many earlycrops. The antiquity of domesticationhas been pushed deeper into the past inmany areas. Today, an eerie synchronic-ity in the timing of the first domesticatesaround the end of the Pleistocene isemerging. Genetic studies of modernand ancient DNA in domesticated plantsand animals are providing remarkableinformation on species distribution andevolution (10, 11). Genetic markers fordomestication are starting to be identi-fied (12). In addition, the number ofarchaeological excavations around theworld has increased by an order of mag-nitude in recent years because of devel-opment and construction as legislatedassessment and salvage of threatenedhistorical and archaeological materialshas been enforced. Lots of new data areavailable in some areas.

In the last 20 years, these advancesand some excellent archaeological detec-tive work have added the easternUnited States to the list of agriculturalcradles (13, 14). A series of original do-mesticates has been identified andradiocarbon-dated. Squash (Cucurbita

pepo) is the first recognized domesti-cated plant from 5025 years B.P. (onlycalibrated dates are used here). Sub-sequent modified species includesunflower (Helianthus annuus var. mac-rocarpus) at 4840 B.P. (Fig. 2) andmarsh elder (Iva annua) at �4400 B.P.Three other seed plants have been iden-tified as potential crops, the subject ofdeliberate planting and harvesting ofstored seed stock, based on their abun-dance in seed assemblages before 2000B.P.: erect knotweed (Polygonum erec-tum), little barley (Hordeum pusillum),and maygrass (Phalaris caroliniana).Maize (Zea mays), the most importantcrop plant in this region in later years,does not arrive until 2150 B.P.

Smith and Yarnell (9) identify theemergence of a ‘‘crop complex’’ in east-ern North America, as more domesti-cates are added to the diet and can beidentified as part of an important set offoods. The essential evidence comesfrom the Riverton site in southeasternIllinois, dating to 3800 B.P. Unusualconditions of preservation, large-scalearchaeological excavation, and a deliber-ate search for plant remains provideddocumentation of the utilization of arich diet and the cultivation of at least 5(and perhaps as many as 7) differentcrop plants. In addition to the specieslisted above, 2 varieties of chenopod(Chenopodium berlandieri) were abun-dant in the archaeobotanical remainsfrom the site.

A crop complex (or plant and animalcomplex) represents the end result of

long experiments with different combi-nations of domesticates and wild foodsto find a coherent whole in terms ofreliable food supply. In various parts ofthe world, as the last cold cycle of thePleistocene was ending human societiesbegan to add more plant species to theirdiet (15–17). The transition from hunt-ing and gathering to full agriculture wasa long process, spanning thousands ofyears. The initial domestication of plantsand animals began within a larger con-text of increasing manipulation andmanagement of a wide range of wildspecies. The individual domesticates of aparticular region were not created all atonce in one place, but apparently overtime, in a number of different locales,by small, interacting societies. Eventuallythese different crops and/or herd ani-mals coalesced into a set of species, orcomplex, that provided the majority ofthe human diet.

This scenario appears to fit the areasfor which we have data. We have sub-stantial information from the early agri-cultural cradle of Southwest Asia. Thepicture in eastern North America is be-coming clearer. Much new data arecoming from China and South America.We know very little about Mexico, Af-rica, Southeast, and Insular Asia. As theSmith and Yarnell study (9) indicates,

Author contributions: T.D.P. wrote the paper.

The author declares no conflict of interest.

See companion article on page 6561.

1E-mail: tdprice@facstaff.wisc.edu.

Pepo Squash 5,000 B.P.Sunflower 4,800 B.P.Marshelder 4,400 B.P.Chenopod 4,000 B.P.

Peanut?Manioc 8,000 B.P.?Chile Peppers 6,000 B.P.

Potato 7,000 B.P.?Quinoa 5,000 B.P.

Arrowroot 8,000 B.P.Yam (D. trifida) 6,000 B.PCotton 5,000 B.P.Sweet potato 4,500 B.P.

Pepo Squash 10,000 B.P.Maize 9,000 - 7,000 B.P.Common Bean 4,000 B.P.

African rice 2,000 B.P.Pearl millet 3,000 B.P.Sorghum 4,000 B.P.

Emmer wheat 10,000 B.PEinkorn wheat 10,000 B.P.Barley 10,000 B.P.

Broomcorn Millet, Foxtail Millet - 8,000 B.P.

Rice 8,000 B.P.Foxnut 8,000 B.P.

Yam (D. alata) 7,000 B.P.?Banana 7,000 B.P.Taro 7,000 B.P.?

Fig. 1. The major centers of primary domestication and dates for the earliest domestication of variousplant and animal species. Illustration by Marcia Bakry.

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visibility and serendipity play a hugerole in our knowledge about agriculturaltransitions. The breakthrough at the Ri-verton site came because of a congru-ence of preservation, large excavation,and an intentional search for plant re-mains. Many other sites, in many partsof the world, may well contain informa-tion on early domesticated species, butthey are known only from small-scale

investigations and often have conditionsof less than ideal preservation. To en-hance our understanding of the originsof agriculture, archaeologists will haveto spend more time in the field openingbig holes looking for the seeds, bones,and other evidence of domesticated spe-cies. The need for more and better in-formation is huge.

The growing body of informationfrom eastern North America does pro-vide insight on this process of domesti-cation and the origins of farming inother parts of the world. At the sametime, like all new research, it raisesmany questions. The evidence for thisregion documents a situation some 4,000years ago where hunter–gatherergroups, living in abundant environmentsand spending substantial periods in sed-entary residences, were changing nature,domesticating a variety of plant speciesthat increased their food supply. Why?And why here? There are numerouslocations in North America, and else-where, where there are many species ofwild plants growing in rich environ-ments inhabited by hunter–gatherer so-cieties where domestication does notappear to have resulted.

The archaeological remains from siteslike Riverton yield evidence of utiliza-tion of a wide range of aquatic re-sources, including fish, bivalves, andsnails, while the white-tailed deer, tur-key, raccoon, rabbits, and squirrels (18)provided the terrestrial animal protein.

The nuts of hickory, walnut, and oakinvariably dominate the plant remains,reflecting the minor importance of theseeds of wild, annual plants. One of themore intriguing questions about the ori-gins of agriculture is raised by the lowincidence of the domesticated speciesand the abundance of wild foods in gen-eral. Why did these societies with suc-cessful, long-term adaptations to re-source-rich river valleys begin tomanipulate plants in the first place?

The initial domestication of cropplants takes place at the beginning ofthe Holocene, �8,000–10,000 years ago,in Southwest Asia, China, Mexico (19,20), and South America. In a few areas,the first species to be changed appearmuch later, however, �5,000 years ago.Another question requiring an answerthen is why are these later regions de-layed in the process of agricultural ori-gins. What differences or distinctionsare involved in this gap?

As the evidence surrounding the ori-gins of agriculture continues to expand,answers to basic questions are graduallybeing discovered. The future of archaeo-logical research is exciting in part becauseit will involve the continuing resolutionof this issue. At the same time, we stilldo not understand why these changeswere initiated, nor why agriculture ex-panded to become the preeminent modeof human subsistence across the globe.Answers to these mysteries may requirecompletely new questions about humansociety and adaptation.

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18. Winters H (1969) The Riverton Culture (Illinois StateMuseum, Springfield).

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Fig. 2. A sunflower seed (Helianthus annuus var.macrocarpus) excavated at Newt Kash Shelter,Kentucky. The missing half of the shell from theseed was used to obtain an AMS radiocarbon dateof ca. 3500 B.P.

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