The ceremonial and medicinal use of peyote (Lophophora Williams) by Native Americans in recent history has been
described in numerous publications (e.g., [22,23]). We present new radiocarbon dates on three peyote specimens excavated from Shumla Caves in the Lower Pecos region of southwest Texas, placing the cultural association of peyote at 5200 14C years BP. Comparative radiocarbon dates on non-pretreated material from the same three specimens provide relevant information on the implications of humic acid contamination. In addition, we present one additional radiocarbon date on an intact peyote button excavated from shelter CM-79 near Cuatro Cie´negas,
Coahuila, Mexico, showing more recent prehistoric use about 835 14C years BP. Other evidence, from ceramics, textiles, ethnography, etc., shows peyote use over the last two millennia and into modern times [1,10,18,21].
Peyote is a small (3 cm in height, 8 cm in diameter), chalky grey-green, spineless globular cactus native to the
The Chihuahuan Desert of northeastern Mexico and adjacent Texas (Fig. 1).
The plant contains mescaline, an alkaloid that produces perceptual and other psychic effects. To our knowledge, the only two archaeological sites where peyote has been recovered, preserved in museum collections, and discussed in the literature are Shumla Caves (and specifically Shumla Cave No. 5, 41VV113) in southwest Texas and shelter CM-79 near Cuatro Cie´negas, Coahuila, Mexico (Fig. 2). Peyote has also been reported by Woolsey at Fields Shelter , by Hicks at a shelter in Crockett County, Texas , and by Sayles at several Texas sites . However, no specimens from any of those sites have been located in collections. The three Shumla Caves’ specimens are not simply desiccated crowns of peyote cacti as reported by previous workers [6,11], but are aggregates of ground peyote mixed with C3plant materials to form flattened hemispheres vaguely resembling peyote buttons (Figs. 3 and 4). Bruhn et al.  demonstrated that the Shumla Caves’ specimens do contain some peyote tissue, as they have a high (2%) mescaline concentration uniquely characteristic of Lophophora, which exceeds concentrations in other plants of this region by orders of magnitude.
The morphological and d13C data supporting this finding, as well as its cultural context and significance, will be discussed elsewhere (Terry et al., in preparation). 2. Archaeological context The two sites featured in the current study are sheltered sites containing an abundance of perishable remains; beyond that fact, there are similarities and differences worth noting. The archaeological peyote finds discussed in this paper come from the Lower Pecos River region of southwestern Texas and the Cuatro Cie´negas region of Coahuila, Mexico e both of which lie within the natural geographic distribution of the cactus (Fig. 2). While both these sites are considered to be within the Chihuahuan Desert , Cuatro Cie´negas lies about 350 km south-southwest of the Lower Pecos, in the Coahuiltecan subprovince of the Chihuahuan-Coahuiltecan Plateau and Ranges , while the Lower Pecos is near the northeastern edge of the Chihuahuan Desert, at the western edge of the Edwards Plateau.
This geographic difference is reflected in differences in physiography, but calcareous soil sand many of the plant species e including the economically important lechuguilla (Agave lechuguilla) and prickly pear (Opuntia spp.) e are common to the two regions. Both regions contain a long and very complete record of desert-adapted foraging that persisted until European contact [25e27]. Perishable remains are common in both regions and include the atlatl, rabbit sticks, nets, cordage, sandals, burden baskets, twined and coiled basketry, plaited matting, and middens with an abundance of desiccated plant materials [13,20,25,27]. The peyote material from the Lower Pecos was recovered from Shumla Caves, a series of nine caves located on the Rio Grande in Val Verde County, Texas. Cave No. 5 (41VV113) was excavated in 1933 by the G.C. Martin expedition , but the provenience for the archaeological assemblage removed from the cave was not recorded during the fieldwork. The published report of the Martin expedition, however, notes ‘a single mummified example (of peyote) from Cave No. 5’ . Schuetz noted the presence of peyote in the Martin expedition materials in her cataloging efforts at the Witte Museum a quarter of a century after the Martin report, but was unable to identify the exact provenience for the peyote specimens from the original excavation records (; Schuetz, personal communication, 2005).
Although no radiocarbon dates have been reported on other materials from Shumla Caves, time-sensitive artifacts in the Shumla Caves’ collections suggest that Shumla Cave No. 5 as well as the other shelters were occupied intermittently throughout the Archaic Period and continuing into the Late Prehistoric Period [13,20]. The artifact assemblage and the associated plant materials indicated that Shumla Cave No. 5 (41VV113) was a residential site containing several burials that had been excavated into midden deposits. Direct dates reported in the current study show that the Shumla Caves peyote specimens fall into the Eagle Nest subperiod of the Middle Archaic Period. In contrast, the peyote from the Cuatro Cie´negas region was recovered from CM-79, a burial cave . The new radiocarbon assay reported in this study was secured from a fragment of a single peyote button strung on a cord with (originally) eight other buttons. The string of peyote buttons was associated with three secondary burials, two of which had been disturbed.
Taylor noted that the remaining undisturbed burial consisted of a skull and mandible that had been placed in a coiled basketry tray . Three dates on plaited matting associated with the burials ranged from 920 75 to 1200 70 BP [2,25], placing this find at the transition between the Late Archaic and Late Prehistoric Periods, much more recent than the Shumla Caves material.
We removed approximately 10 mg of material from the interior of each specimen. An acid-base acid pretreatment was performed on plant material: two soaks in hot (90 C) 1 M HCl; followed by two soaks in hot 1 M NaOH; and then two additional hot soaks in 1 M HCl. Afterward, samples were repeatedly rinsed with ultrapure distilled, de-ionized water. The remaining plant material was combusted to CO2 and converted to graphite for an accelerator mass spectrometer target. A split of the CO2 was taken for stable isotope analysis (d13C). Radiocarbon measurements were conducted at Lawrence Livermore National Laboratory’s Center for Accelerator Mass Spectrometry (CAMS).
New radiocarbon dates on three altered peyote specimens excavated at Shumla Caves, Val Verde County, Texas, plus
the first direct radiocarbon date on one of the specimens of natural peyote excavated from shelter CM-79, near Cuatro Cie´negas, and Coahuila, is shown (corrected for d13C) in Table 1. The three Shumla Caves’specimens have statistically indistinguishable radiocarbon ages of 5160 45, 5200 35, and 5210 35 14C years BP, with a weighted mean of 5195 20 14C years BP, calibrated to 4045e3960 BC (2s), calculated using the ‘‘R_Combine’’ function of the OxCal Calibration Program [4,24]. The radiocarbon date for the Cuatro Cie´negas peyote is 835 35 14C years BP, calibrated to 1070e1280 AD (2s).
Dating by inference The antiquity of peyote use has previously been estimated from four principal types of information. (1) From a 16th Century history of Mexico , peyote use by the Chichimecos people was inferred to date back to 300 BC . (2) Archeological ceramic artifacts with peyote motifs, from Colima, Mexico, date from 100 BC to 300 AD . (3) The radiocarbon dating of other plant materials recovered from the same archeological site as peyote specimens yielded a date by the association of 810e1070 uncal AD at Cuatro Cie´negas . (4) More recently, examples of a particular genre (Pecos River style) of rock art found in the Lower Pecos River region of southwest Texas that sometimes incorporates peyote motifs  have been dated to between 2750 and 4200 14C years BP [15e17]. All these previous estimates for the antiquity of peyote use in the Chihuahuan Desert indicated time points or intervals more recent than the ages determined by our radiocarbon dating of the Shumla Caves’ specimens at 5195 20 14C years BP.