Documenting plant domestication: The consilience of biological and archaeological approaches

Map of Mexico showing the present-day geographical range of the wild progenitor populations of the domesticated common bean (red) (8) and maize (yellow) (7), as well as the area where wild pepo squash was likely initially brought under domestication, based on archaeological evidence (orange) (14, 15). Also shown are the three areas (Tamaulipas, Tehuacán, Oaxaca) where dry caves have yielded much of the available evidence regarding the early pre-Columbian history of these three major crop plants. The associated chart indicates when domesticated common bean, maize, and pepo squash initially appear in the archaeobotanical sequences of Oaxaca, Tehuacán, and Tamaulipas, which along with the Southwest United States form a south to north transect (note degrees north latitude designations). Expressed in calibrated calendar years ago, the dates of initial appearance of these three major crop plants in these four regions are based on direct AMS radiocarbon age determinations (1, 3, 4, 13–15). The age determination for the initial appearance of pepo squash in Tehuacán is based on an AMS date of 7,100 ± 50 ¹⁴C yr B.P. (β123040)—about 7,900 calendar years ago, obtained on seed 201 from Coxcatlán Cave (square 148, level 11, zone XIV).