The effects of charring on common bean (Phaseolus vulgaris L) seed morphology and strength

TitleThe effects of charring on common bean (Phaseolus vulgaris L) seed morphology and strength
Publication TypeJournal Article
Year of Publication2021
AuthorsHart, JP
JournalJournal of Archaeological Science: Reports
Date PublishedApr-27-2021
KeywordsCharring, common bean, Experimental archaeology, Seed identification

Bean (Phaseolus L. spp.) is one of three crops along with maize (Zea mays L. ssp. mays) and squash (Cucurbita L. spp.) that dominated Native American agricultural systems throughout the Western Hemisphere. Common bean (Phaseolus vulgaris L.) was the species present in northeastern North America and was the last of the three crops to be adopted there. Common bean macrobotanical remains become archaeologically visible as charred whole seeds and more typically cotyledons around cal. CE 1250. After that time, common bean is scare in the archaeological record, especially when compared to charred maize kernels. This has led paleoethnobotanists to suggest charred common bean seeds do not preserve well because of physical changes during charring. The results of charring experiments presented here indicate that cotyledons of charred dried common bean seeds heated at temperatures between 220 ◦C and 260 ◦C maintain strength, identifying characteristics, are little changed in size, and so are likely to survive and be identified. Common bean seeds carbonized at higher temperatures lose substantial mass, exhibit surficial fissures, and consequently lose strength, suggesting they are unlikely to survive intact if at all in the archaeological record. Rehydrated seeds lose considerable strength at all temperatures and are less likely than carbonize dried beans to survive in the archaeological record.

Short TitleJournal of Archaeological Science: Reports