Stable carbon isotope values (δ13C) of purslane (Portulaca oleracea) and their archaeological significance. (June 2016)

• Record Type: Journal Article
• Authors: Tankersley, Kenneth Barnett; Conover, Denis G.; Lentz, David L.
• Is Part Of: Journal of archaeological science. Volume 7(2016)
• Page Start: 189
• Page End: 194
• Publication Date: 2016-06
• Subjects: Stable carbon isotope value -- Photosynthesis -- Archaeobotany -- Paleobotany -- Paleodiet -- Common purslane (Portulaca oleracea) -- Maize (Zea mays) -- Eastern North America -- Late Holocene -- Bioarchaeology; Archaeology -- Periodicals; Archaeology -- Research -- Periodicals; 930.1
• DOI: 10.1016/j.jasrep.2016.04.009
• Languages: English
• ISSNs: 2352-409X

Abstract

Abstract: Elemental Analyzer Isotope Ratio Mass Spectrometry was used to determine the δ 13 C values of common purslane (Portulaca oleracea), a highly edible and nutritious annual succulent and member of the Portulacaceae family, which uses both C4 fixation and Crassulacean acid metabolism (CAM) photosynthesis. The δ 13 C values for the plant range between − 11.2‰ and − 20.5‰ (C4 − 11.2‰ to − 13.9‰, CAM − 17.6‰ to − 20.5‰), which overlaps with δ 13 C values for maize (Zea mays) − 9.1‰ to − 17.3‰. Both plants occur on late Holocene archaeological sites in eastern North America and likely contributed to the δ 13 C ratios reported for ancient human collagen and hydroxyapatite. Taphonomically, P. oleracea has a lower archaeological visibility because it is completely edible and the seeds are tiny (0.02 to 0.76 mm) in comparison to maize kernels and cobs. Therefore, we can no longer assume that maize was the only significant plant food in the late Holocene diet of eastern North America, which elevated δ 13 C ratios in ancient human tissues. Highlights: δ 13 C values for C4 Portulaca oleracea range between − 11.2‰ and − 13.9‰. δ 13 C values for CAM P. oleracea range between − 17.6‰ and − 20.5‰. δ 13 C values of P. oleracea overlap with δ 13 C values for Zea mays maize. P. oleracea occurs on late Holocene archaeological sites in eastern North America. P. oleracea likely contributed to the δ 13 C ratios in ancient human tissues.