A recent study led by CIBIO, the University of the Azores, CSIC and CREAF shows that the navigations of the Vikings could have taken them to the Azores about 700 years before the arrival of the Portuguese. The results, published in the journal PNAS, have been obtained through sediment samples from different lakes and environmental reconstructions.

The Azores are a group of volcanic islands located in the Atlantic Ocean, about 1,500 km northwest of Portugal. Until now, there was a consensus that they had been uninhabited until the arrival of the Portuguese in the 15th century, but a work published in PNAS has found that the first settlers actually came from northern Europe during the Viking Age. The data point to the fact that they would have taken advantage of favorable climatic conditions to arrive from the north, which were less good for arriving from the east (Portugal).

"We have conducted multidisciplinary analyses of lake sediments and they show that there were changes in the ecosystems of the Azores related to the arrival of humans. Moreover, since this first impact the ecosystems have never returned to their previous pristine state. There is clear evidence of slashing and burning of natural vegetation and a consequent increase in soil erosion, the trophic state of the lakes and the introduction of new species," explains Sergi Pla Rabés, CREAF researcher and author of the paper. The sediment cores have been recovered from the lake bottom of the islands of São Miguel, Pico, Terceira, Flores and Corvo and allow us to analyze the passage of time in the soil over thousands of years. Crop pollen (cultivated cereals) and fungal spores associated with cattle feces, symbols of domestication, have also been identified.

With this article we wanted to go beyond conventional articles reconstructing past environmental and climatic changes. We have done climate modeling, yes, but with a volume of data from the entire archipelago that shows that it is evident that humans had played a very predominant role in modifying the landscape and ecosystems of all the islands.

SERGI PLA RABÉS, CREAF researcher and professor at the UAB.

In addition to geological techniques, chemical, physical and biological techniques have also been used to extract further evidence of human passage. For example, "the intestines of large mammals produce in abundance two compounds that are recorded in the lake sediments: sterols and stanols. They are an unequivocal indicator of the presence of large mammals and, in addition, there are stanols that differentiate human origin (rich in coprostanol) and large ruminant mammals (rich in stigmastanol)" explains Timothy Shanahang (University of Texas at Austin). And "due to their geographical position, in the middle of the Atlantic Ocean, they could not be other large mammals than those domesticated by man", clarifies Santiago Giralt (GEO3BCN-CSIC)

The authors of the research already expected to find these signs of human presence, but at a more recent date. Thus, the surprise has been that all these results place the Azores as inhabited about 700 years before what was known. These dates do not coincide with the arrival of the Portuguese. For this reason, the team argues that this work shows that, despite having abundant historical information, to have an accurate idea of the past it is necessary to promote interdisciplinary work between the Humanities and Natural Sciences and really know what our history has been.

Reference article

Raposeiro, P. M. et al. (2021). Climate change facilitated the early colonization of the Azores Archipelago during medieval times. Proceedings of the National Academy of Sciences of the United States of America, 118(41), e2108236118. https://doi.org/10.1073/pnas.2108236118