High-elevation climatic and environmental variability during the early hominin occupations at Melka Kunture (Upper Awash, Ethiopia)

For more than 30 years, stable carbon and oxygen isotopic analyses of herbivore skeletal tissues have been widely used to reconstruct animal life history and behavior, including diet, physiology, mobility, and past climate and environmental conditions. Tooth enamel is particularly well-suited for such investigations because its high crystallinity and low organic content confer exceptional resistance to diagenetic alteration, preserving primary isotopic signals over geological timescales. Moreover, because enamel forms incrementally, it enables the extraction of isotopic time-series information that reflects the period of tooth mineralization.

Here, we explore the potential of stable isotope analysis to maximize paleoecological data retrieval from Paleolithic faunal assemblages, using the archaeological site complex of Melka Kunture (Upper Awash, Ethiopia) as a case study. Melka Kunture is a dense cluster of Pleistocene and Holocene sites located in the Ethiopian highlands at elevations of 2000-2200 m above sea level, and it is inscribed on the UNESCO World Heritage List. Its geoarchaeological sequence, dated between 2,000,000 and ~5,000 years ago, provides a rare opportunity to investigate high-elevation past ecosystems in the tropics, where collagen preservation is often poor and enamel-based approaches are particularly valuable. By combining bulk and intra-tooth isotope analyses of herbivore tooth enamel with faunal, pollen, and phytolith evidence, we assess the complementarity of proxies to detect climatic and environmental variability over time and its implications for human and mammalian evolution. The results demonstrate how stable isotope analysis can substantially enhance the interpretation of Paleolithic records, particularly in ecologically marginal settings. Finally, we highlight the value of integrated, multi-proxy approaches when reconstructing past ecosystems