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AbstractSea level rise and climate change are shaping present societies, particularly those on oceanic islands. Few historical examples could serve as references for these changes. One such potential model is the Saudeleur Dynasty with its capital Nan Madol on the Pacific Island of Pohnpei. However, the timing of its construction, as well as the dynasty's fluctuations and potential environmental influences, has remained unresolved. Through the analyses of 230Th ages on 171 dates on corals fragments used as building materials and charcoal 14C ages from excavations, 2 major construction phases spanning from the 10th to the 15th century CE can be discerned. The results show that the first phase of the site's construction, spanning the 10th–12th century, marked the dynasty's rise. The second period, spanning from the late 12th to the early 15th century, provides the most substantial evidence for the demise of the island-scale chiefdom and a significant societal reorganization. The phases are centuries earlier than previously believed. With this new evidence, we propose the hypothesis that variations in the El Niño-Southern Oscillation and subsidence-related sea level rise presented major challenges for building and maintaining Nan Madol, and thus, influenced the course of the island's history. This case serves as a compelling example of how adverse climatic conditions can spur investments—in this case, in seawater defense under high sea levels—yet ultimately may contribute to abandonment. It offers lessons for island nations, showcasing coastal resilience in the face of worsening catastrophic events that unfolded over generations.

Haiyang Wang,1,2,* Lanxiang Liu,1,3,* Xuechen Rao,1,2,* Tingjia Chai,1,* Benhua Zeng,4 Xiaotong Zhang,1 Ying Yu,1 Chanjuan Zhou,1 Juncai Pu,1,3 Wei Zhou,1 Wenxia Li,4 Hanping Zhang,1,3 Hong Wei,4 Peng Xie1–3 1NHC Key Laboratory of Diagnosis and Treatment on Brain Functional Diseases, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, People's Republic of China; 2College of Biomedical Engineering, Chongqing Medical University, Chongqing 400016, People's Republic of China; 3Department of Neurology, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, People's Republic of China; 4Department of Laboratory Animal Science, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, People's Republic of China*These authors contributed equally to this workCorrespondence: Peng XieNHC Key Laboratory of Diagnosis and Treatment on Brain Functional Diseases, The First Affiliated Hospital of Chongqing Medical University, 1 Youyi Road, Yuzhong District, Chongqing 400016, People's Republic of ChinaTel +86-23-68485490Email xiepeng@cqmu.edu.cnHong WeiDepartment of Laboratory Animal Science, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, People's Republic of ChinaTel +86-23-68752051Email weihong63528@163.comIntroduction: Recently, an increasing number of studies have focused on commensal microbiota. These microorganisms have been suggested to impact human health and disease. However, only a small amount of data exists to support the assessment of the inï¬'uences that commensal microbiota exert on olfactory function.Methods: We used a buried food pellet test (BFPT) to investigate and compare olfactory functions in adult, male, germ-free (GF) and specific-pathogen-free (SPF) mice, then examined and compared the metabolomic profiles for olfactory bulbs (OBs) isolated from GF and SPF mice to uncover the mechanisms associated with olfactory dysfunction.Results: We found that the absence of commensal microbiota was able to influence olfactory function and the metabolic signatures of OBs, with 38 metabolites presenting significant differences between the two groups. These metabolites were primarily associated with disturbances in glycolysis, the tricarboxylic acid (TCA) cycle, amino acid metabolism, and purine catabolism. Finally, the commensal microbiota regulation of metabolic networks during olfactory dysfunction was identified, based on an integrated analysis of metabolite, protein, and mRNA levels.Conclusion: This study demonstrated that the absence of commensal microbiota may impair olfactory function and disrupt metabolic networks. These findings provide a new entry-point for understanding olfactory-associated disorders and their potential underlying mechanisms.Keywords: gut microbiota, germ-free, olfactory bulb, metabolomic, gas chromatography-mass spectrometry