In this lecture, I present the results of excavations and artifact analyses focused on the site of Hatun Machay, a shelter located in the high puna of Ancash, Peru. The high-altitude puna of the Andes is a unique ecological region, historically considered “marginal” for forager occupation on account of hypoxic conditions, intense solar radiation, difficult terrain, and relatively sparse resources (Aldenderfer 1998). Nonetheless, the region has yielded significant archaeological data that not only attest to a substantial human presence, but also showcase remarkable human adaptability including surprisingly early occupation of high altitudes (Rademaker et al. 2014; Rademaker and Moore 2018). This site presents a unique lens to understand human responses to dynamic environmental conditions, with ~12,000 years of occupation by humans from at least the Early Holocene into the present. In this talk, I discuss findings from the 2024 and 2025 excavations of the site, linking material evidence to regional-scale environmental conditions during the Holocene.