- The stigmastanols attributed to cows and goats were found in sediment layers dated to between 700 and 850 AD.
- Because of their isolation in the middle of the Atlantic, the Azores did not have large mammals before they were brought in by humans.
- The researchers also found charcoal particles, indicating that the explorers were burning forests to provide grazing land for livestock.
- Depending on climatic conditions, Norse sailors may have used unusually strong northerly winds to sail to the archipelago.
Scientists have found evidence that the first visitors to the Azores were Norse sailors who arrived 700 years before the Portuguese, who are believed to have discovered the string of North Atlantic volcanic islands in the 15th century.
Analyzing sediment layers in various lakes in the archipelago, an international team found traces of fecal compounds from non-native ruminants such as cows or sheep that date back to between 700 and 850 AD.
They also found an increase in charcoal particles, possibly because explorers or colonists were setting large fires, and a drop in native tree pollen, suggesting that someone burned parts of the forest to provide grazing land for cattle. Was.
New research counters the long-standing belief that 15th-century Portuguese sailors were the first humans to arrive in the Azores, 900 miles off the coast of Portugal.
‘Even with the abundant available historical information allowing us to have a very accurate picture of the past,’ said co-author Santiago Giralt, a paleontologist at Geosciences Barcelona, promoting interdisciplinary research between the humanities and the natural sciences. It is necessary to give , said in a statement.
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Analysis of sediment cores taken from Pico Island’s Lake Peixinho (pictured) showed an increase in 5-beta-stigmasterol, commonly found in livestock waste, dated to between 700 and 850 AD, dating back to 1427 by the Portuguese. It was long before I came.
Now an exotic holiday destination, the Azores first began to appear on European maps in the 1350s.
The first archaeological evidence of humans on the islands, however, dates back to 1427, when Portuguese navigator Diogo de Silves, under the command of Prince Henry the Navigator, landed on the island of Santa Maria while searching for new routes to Asia.
Flores Corvo Island arrived 25 years later and eventually, more Portuguese arrived and colonized the archipelago.
The natural record tells a different story, however: sediment samples are valuable tools in peeling back the layers of history because material that sinks to the bottom of the lake is often preserved as new levels of sediment are layered on top.
A timeline indicating various evidence for human presence in the Azores in the Early Middle Ages
Because the Azores are isolated in the Atlantic, large mammals did not live on the Azores before the arrival of humans. So stigmastanol found in an 8th-century sediment layer on Pico Island can be attributed to cows, sheep, or other ruminants that were brought ashore by sailors.
This research has been published in the Scientific Journal Proceedings of the National Academy of Science.
Analysis of sediment cores taken from Lake Pixinho in the Pico Island of the Azore found an increase in 5-beta-stigmasterol, a compound commonly found in livestock waste, dating back to between 700 and 850 AD.
“Fecal sterols and stanols are produced in great abundance in the intestinal track of mammals and are well preserved in lake sediments,” said co-author Timothy Shanhang of the University of Texas, a unique and clear tracer of the presence. provide. of large mammals during the last time interval.’
But large mammals did not live on the Azores before the arrival of humans, ‘because of their geographic location, in the middle of the Atlantic Ocean,’ Giralt said.
Diogo de Silves landed on the island of Santa Maria in 1427, searching for new routes to Asia.
“Therefore, the discovery of coprostanol in sediments can be attributed to human presence, and the finding of stigmastanol can be attributed to ruminants such as cows, sheep or goats,” he said.
Samples from Lake Caldeirao on Corvo Island give similar results, although those sterols are thought to be about a century later than those from Pico Island.
The study also determined that sediment from a lake on another island showed evidence of non-native ryegrass.
“As we demonstrate in this work, early human settlement on the islands created a profound environmental and ecological disturbance,” lead author Pedro Raposero of the University of the Azores said in the release.
Raposero said their study, supported by the Spanish National Research Council, ‘highlights the challenge in relying on the historical record to identify states relative to ecosystems or landscape disturbances.’
The Azores are a chain of nine volcanic islands in the North Atlantic about 900 miles off the coast of Portugal and 930 miles northwest of Morocco.
Based on simulations of climatic conditions during that time frame, Giralt’s team believes that these early visitors were Norse seamen who took advantage of unusually strong northerly winds and weak westerly winds to move from northern Europe. Were were
Giralt said in a statement, “The westerly winds prevail in the Atlantic due to the rotation of the Earth.
Climatic conditions during that time frame suggest that Norse seamen may have taken advantage of unusually strong north winds and weak westerly winds to move from northern Europe to the Azores in the 8th century.
The latest research is a 2015 study out of Cornell University, which found genetic similarities between Azorean rats and rodents from northern Europe.
Evolutionary biologist Jeremy Searle, lead author of the Cornell report, ‘there is indeed strong data to support what is clearly very gratifying.
Earlier, Portuguese archaeologist Nuno Ribeiro has claimed That alleged rock art and a small number of underground structures on the islands placed human arrival more than 2,000 years ago.