Bridging Ethnobotany and Ethno-Astronomy: A Systematic Review of Ethiopia's Medicinal Plant Diversity (1950–2024) and the Unexplored Potential of Celestial Harvesting Cues in Traditional Healthcare

Abstract

Ethiopia's rich biocultural heritage encompasses extraordinary medicinal plant diversity and sophisticated indigenous astronomical knowledge systems, yet the intersection between these domains remains critically understudied. This systematic review synthesizes ethnobotanical data from 59 studies (2010–2022) documenting 525 medicinal plant species across 113 families and 333 genera, with 44 endemic species and nine (27.3%) endangered. The review uniquely bridges ethnobotany with ethno-astronomy, introducing the emerging paradigm of ethno-astrobotany, the study of celestial influences on plant selection, harvesting, and medicinal efficacy. The Borana Oromo lunar-stellar calendar, developed around 300 BC, demonstrates remarkable predictive skill (r = 0.889 for rain onset, RMSE = 3.3 days) through observation of 12 anchor stars, while similar systems among the Amhara, Tigray, Afar, Somali, Sidama, and Konso communities guide seasonal forecasting and agricultural timing. Global evidence indicates that lunar phases significantly influence phytochemical composition, full moon harvests yield higher essential oils and bioactive compounds, as demonstrated in Withania somnifera and Oliveria decumbens. However, in Ethiopia, no systematic study has examined the relationship between ethno-astronomically determined harvesting times and pharmacological properties of medicinal plants. Urgent threats include elder attrition, modernization, climate variability, and habitat loss, accelerating biocultural erosion. This review establishes an integrated research agenda combining ethnographic documentation, phytochemical validation, longitudinal monitoring, and participatory approaches with traditional healers. Policy implications include evidence-based harvesting guidelines, conservation planning integrating celestial calendars, culturally responsive STEM education, and protection of indigenous knowledge rights. Preserving Ethiopia's interwoven biological and cultural heritage demands immediate, interdisciplinary action.