Archaeobotanical Evidence for Pearl Millet (Pennisetum Glaucum) in Sub-Saharan West Africa

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The origin of agriculture in sub-Saharan West Africa has been associated with the Kintampo, a ceramic Late Stone Age (LSA) cultural complex occupying the region of present-day Ghana during the 4th millennium BP. Archaeological evidence indicates that Kintampo peoples possessed a material culture similar to that of other early farmers, including chipped and ground projectile points, ground stone axes, grinding stones and ceramics. Sedentary village occupation is indicated by remains of daub architecture, occasionally with stone foundations; however rock-shelters also were inhabited (Davies 1962; Flight 1968; Dombrowski 1980; Stahl 1985; Casey 1993). Although often described as the earliest settled agriculturalists of West Africa, the nature of Kintampo subsistence has been the object of speculation for several decades (Davies 1960; Flight 1976; Posnansky 1984; Stah11993; Anquandah 1993). Archaeologists have proposed that Kintampo peoples cultivated various cereals and yams (Dioscorea rotundata, D. cayenensis), as well as crop mixtures (Davies 1962: 291; Flight 1976: 218-19; Anquandah 1993: 260); however, direct evidence relating to subsistence has been sorely lacking (Andah 1993: 250-53). Most available data are derived from one rock-shelter site, K6, located in central Ghana near the tropical forest and forest-savanna mosaic boundary (FIGURE 1) (Stahl 1985: 138-42). This locality has produced evidence for the exploitation of domestic ovicaprids (cf. Capra) and hunting of species attracted to clearings or settlement areas, such as large rodents (Thryonomys swinderianus). Plant remains include tropical forest margin species such as oil palm (Elaeis guineensis), incense tree (Canarium schweinfurthii), hackberry (Celtis) and probable legumes (cf. Fabaceae). Related palynological studies indicate that oil palm was cultivated or managed in the region by at least 3500 BP (Sowunmi 1981: 136; Talbot et al. 1984: 185). New macrobotanical data bearing on this question have been recovered during recent excavations at the Birimi site in northern Ghana (Casey et al. 1997). Analysis of Birimi archaeobotanical samples reported in this paper have confirmed the association of domesticated pearl millet (Pennisetum glaucurn) with the Kintampo complex.

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The Birimi site is situated in an area of dry woodland savanna atop the Gambaga Escarpment in northern Ghana (FIGURE 1). A rich assemblage of Kintampo artefacts has been recovered on the surface and throughout the complex series of pits and lenses of daub architectural remains preserved below. The site extends for approximately one kilometre on both sides of a gully, which was formed by an ancient stream. Eroding sections of the gully edges have exposed a portion of a Kintampo village including the remains of at least 34 daub architectural units. Excavated sections include a profile of the gully, which revealed a well-defined pit feature (FIGURE 2), and area excavations farther upslope. Radiocarbon determinations for the gully profile pit feature based on wood charcoal are summarized in TABLE I (Casey et al. 1997).

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TABLE 1. AMS [sup.14]C
dates from gully
profile pit feature.

depth    lab                 material             uncalibrated
(cm)     no.                                      radiocarbon
                                                  year BP(*)

32-42    B-099308            charcoal             3310 [+ or -] 110
42       B-099306            charcoal             3240 [+ or -] 90
45-50    TO-8173             grain                2960 [+ or -] 370
50-60    TO-8172             grain                3460 [+ or -] 200
62       B-099307            charcoal             3550 [+ or -] 40

depth    dendro-calibrated   calibration curve
(cm)     age range (BC)(*)   intercept (cal BC)

32-42    1735-1453           1596-1528
42       1618-1413           1512
45-50    1620-795            1130-1250
50-60    1980-1520           1740
62       1942-1777           1883

(*) 68% probability

Birimi was sampled extensively for charred macrobotanical remains. …