Selective erosion of pharmacopeial knowledge: a two-millennium diachronic analysis of Prunus dulcis (Mill.) D.A. Webb in Northeastern Morocco

Abstract

Background: The persistence of ethnobotanical knowledge is a selective cultural process shaped by population needs, ecological factors, and modernisation. Quantitative diachronic analyses integrating historical written sources with contemporary field data remain rare for single-taxon studies in the Mediterranean region. Methods: This study reconstructs the two-millennium transmission trajectory of Prunus dulcis (Mill.) D.A. Webb across four sources: Dioscorides (De Materia Medica, 1st century CE), Ibn Sina (Canon of Medicine, 11th century CE), Ibn Al-Baytar (Kitab al-Jami’, 13th century CE) and contemporary field data collected in Northeastern Morocco from 2017 to 2019, involving 1,177 informants. Results: A total of 148 medicinal uses were documented across 14 ICPC-2 groups. Jaccard similarity among the three historical sources was high (between 0.769 and 0.857). Ibn Sina’s absence from Ibn Al-Baytar’s citation indicates this similarity reflects parallel convergence on shared sources rather than direct transmission. Similarity between contemporary NE Morocco and historical sources was markedly lower (between 0.167 and 0.25). Preparation knowledge showed the most severe erosion (between 0.083 and 0.111); non-medicinal uses proved more resistant. Conclusions: These findings document a taxon-specific pattern of selective pharmacopeial knowledge attrition and demonstrates procedural knowledge is more vulnerable to erosion than declarative knowledge. Keywords: Diachronic analyses; Ethnobotanical knowledge, Prunus dulcis; Northeastern Morocco, Knowledge erosion