The earliest adobe monumental architecture in the Americas.

Adobe bricks, or mud bricks, are construction elements which have defined major architectural traditions in the Andes over thousands of years. From Moche pyramids and the ancient city of Chan Chan in pre-Hispanic times, to Spanish casonas of the colonial period and rural houses in contemporary South America, adobe has been a central component in Andean architecture. Discovery of the remains of an early monumental building constructed primarily of adobes at Los Morteros (lower Chao Valley, north coast of Peru) places the invention of adobe architecture before 5,100 calendar years B.P. The unique composition, internal structure, and chronology of the adobes from Los Morteros show the beginnings of this architectural technique, which is associated with El Niño rainfall and the construction of the earliest adobe monumental building in the Americas. We propose that adobe architecture became a major Andean tradition after a long period of technical evolution and experimentation with both shape and composition.

Coastal heritage, global climate change, public engagement, and citizen science.

Climate change is threatening an uncalculated number of archaeological sites globally, totaling perhaps hundreds of thousands of culturally and paleoenvironmentally significant resources. As with all archaeological sites, they provide evidence of humanity's past and help us understand our place in the present world. Coastal sites, clustered at the water's edge, are already experiencing some of the most dramatic damage due to anthropogenic climate change, and the situation is predicted to worsen in the future. In the face of catastrophic loss, organizations around the world are developing new ways of working with this threatened coastal resource. This paper uses three examples from Scotland, Florida, and Maine to highlight how new partnerships and citizen science approaches are building communities of practice to better manage threatened coastal heritage. It compares methods on either side of the Atlantic and highlights challenges and solutions. The approaches are applicable to the increasing number of heritage sites everywhere at risk from climate change; the study of coastal sites thus helps society prepare for climate change impacts to heritage worldwide.

Archaeological climate proxies and the complexities of reconstructing Holocene El Niño in coastal Peru.

Archaeological evidence plays a key role in longitudinal studies of humans and climate. Climate proxy data from Peruvian archaeological sites provide a case study through insight into the history of the "flavors" or varieties of El Niño (EN) events after ∼11 ka: eastern Pacific EN, La Niña, coastal EN (COA), and central Pacific or Modoki EN (CP). Archaeological proxies are important to the coastal Peruvian case because more commonly used paleoclimate proxies are unavailable or equivocal. Previously, multiproxy evidence from the Peruvian coast and elsewhere suggested that EN frequency varied over the Holocene: 1) present in the Early Holocene; 2) absent or very low frequency during the Middle Holocene (∼9 to 6 ka); 3) low after ∼6 ka; and 4) rapidly increasing frequency after 3 ka. Despite skepticism about the reliability of archaeological proxies, nonarchaeological proxies seemed to confirm this archaeological EN reconstruction. Although there is consensus that EN frequency varied over this period, some nonarchaeological and archaeological proxies call parts of this reconstruction into question. Here we review Holocene EN frequency reconstructions for the Peruvian coast, point to complexities introduced by apparent contradictions in a range of proxy records, consider the impact of CP and COA phenomena, and assess the merits of archaeological proxies in EN reconstructions. Reconciling Peruvian coastal paleoclimate data is critical for testing models of future EN behavior under climate variability.

Indigenous oyster fisheries persisted for millennia and should inform future management.

Historical ecology has revolutionized our understanding of fisheries and cultural landscapes, demonstrating the value of historical data for evaluating the past, present, and future of Earth's ecosystems. Despite several important studies, Indigenous fisheries generally receive less attention from scholars and managers than the 17th-20th century capitalist commercial fisheries that decimated many keystone species, including oysters. We investigate Indigenous oyster harvest through time in North America and Australia, placing these data in the context of sea level histories and historical catch records. Indigenous oyster fisheries were pervasive across space and through time, persisting for 5000-10,000 years or more. Oysters were likely managed and sometimes "farmed," and are woven into broader cultural, ritual, and social traditions. Effective stewardship of oyster reefs and other marine fisheries around the world must center Indigenous histories and include Indigenous community members to co-develop more inclusive, just, and successful strategies for restoration, harvest, and management.