Colonization of the Azores began 700 years ago

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Human occupation of the Azores Islands began 700 years earlier than the start of Portuguese colonization of the island, which, as historical documents indicate, was in the 15e century. This is the main finding of new research conducted by an international multidisciplinary team of scientists with the participation of CSIC. The study published in the journal PNAS, reconstructs when, how and under what climatic conditions the islands were colonized, in addition to the impacts of the first human settlements on the ecosystems, by analyzing sediment cores recovered in several lakes of the islands. The authors of the study suggest that the first settlers came from northern Europe, and that their arrival occurred in conjunction with favorable climatic conditions to allow navigation to these volcanic islands, which are located some 1,450 km from European coasts.

Until recently, the consensus was that the Azores were not colonized until the Portuguese arrived in search of new routes to Asia. According to historical sources, the Portuguese first arrived on the island of Santa Maria in 1427 AD and in 1452 AD they reached the Flores Corvo Islands. However, this study determines that humans first occupied these islands during the late High Middle Ages, between AD 700 and 850.

According to Santiago Giralt, researcher at Geosciences Barcelona (Geo3BCN-CSIC) and co-author of the article, “this study highlights that, even with a lot of historical information available allowing to have a very precise picture of the past, it is necessary to promote interdisciplinary research, between the human and natural sciences, to fully understand our history.

Using geological, chemical, physical and biological analytical techniques, the researchers dated and characterized five sediment cores recovered from the lakes of the islands of Sao Miguel, Pico, Terceira, Flores and Corvo. The researchers found both sterols, which are a fraction of the organic matter abundant in mammalian feces, as well as coprophilic fungal spores in sediment samples, which have been used as indicators of human activity related to the introduction of cattle.

“Fecal sterols and stanols are produced in great abundance in the mammalian intestinal tract and are well preserved in lake sediments, providing a unique and unambiguous tracer of the presence of large mammals during past time intervals,” said said Timothy Shanahang, University of Texas researcher and co-author of the study. “In addition, the compounds (such as coprostanol and stigmastanol) produced in the intestines of humans and cattle differ, which allows us to distinguish them.”

“Due to its geographical location, in the middle of the Atlantic Ocean, large mammals were not present in the Azores islands,” Giralt said. “Therefore, the discovery of coprostanol in sediments can be attributed to human presence, and the discovery of stigmastanol can be attributed to ruminants, such as cows, sheep or goats.”

Pollen, fossil and charcoal analyzes

The researchers also used other indicators, such as pollen, plant macrofossils or charcoal particles, to study human impacts on the island’s environment. Although official documentary sources have described the Azores as heavily forested and pristine, this study highlights the challenge of relying on historical records to identify relative states of ecosystems or landscape disturbances, ”said Pedro Raposeiro, researcher at the University of the Azores and responsible for the author of the study.

The researchers also carried out climate simulations to better understand the climatic conditions during the initial occupation of the archipelago. Based on these models and previously published archaeological and genetic studies, the study authors suggest that the Scandinavians were most likely the first settlers of the Azores. These explorers found favorable climatic conditions, which allowed them to navigate to the archipelago during a period of abnormal north, and weakened westerly winds, facilitating the arrival of northern Europe.

“Due to the Earth’s rotation, westerly winds dominate in the Atlantic Ocean, which strengthen or weaken according to the NAO (North Atlantic Oscillation), the primary climatic mode that controls atmospheric circulation in the northern hemisphere. The NAO is modulated at the same time by the pattern of the East Atlantic, which controls the intensity of the north winds, ”explains Santiago Giralt.

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In addition to the participation of researchers from the CSIC of GEO3BCN-CSIC, the Research Center for Ecological and Forestry Applications (CREAF), the Marine Research Institute (IIM-CSIC) and the National Museum of Natural Sciences (MNCN-CSIC) , the study also counts on the participation of researchers from several national and international institutions such as the University of the Azores (UAC-Portugal), the University of La Coruña (UDC), the University of Barcelona (UB) and the University of Texas at Austin (USA). The study also included the collaboration of researchers from the Royal Netherlands Institute for Research of the Sea (NIOZ) (Netherlands), Brown University (United States), Portuguese Institute of the Sea and Atmosphere (IPMA) (Portugal), Dom Luiz Institute of the University of Lisbon (Portugal), Institute of Environmental Sciences and Technologies (ICTA), University of Evora (Portugal), University Amsterdam (Netherlands), University of Bern (Switzerland) and Edith Cowan University (Australia).


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