Researchers from the University of Alaska Fairbanks (UAF) made the discovery as they excavated a total of 17 hearths from different time periods at the Upward Sun River site near the Tanana River in central Alaska.
To identify the fish remains, a team led by UAF postdoctoral researcher Kyungcheol Choy employed the same technique used to reconstruct ancient diets from cooking pottery and food residues. In this case, they analyzed the chemistry of sediments from each hearth.
"Most of archaeologists are interested in bone remains, human bones and pottery residues to reconstruct the food consumption in ancient people. However, fishbone remains are not preserved well and it's difficult to detect fish consumption in pre-pottery people," Choy told Discovery News.
The researchers examined chemical profiling of the hearth residues by carrying out stable isotope analysis and lipid residue analysis. In this way, they determined whether the food cooked there came from land animals and plants or aquatic ones.
"We confirmed the Upward Sun River site was used for cooking salmon and freshwater fish even though the site is located in the central Alaska," Choy said.
High nitrogen values in hearths indicated that fish was cooked in hearths dating to 11,800 and 11,500 years ago.
More in detail, the carbon ratios from lipids in hearths pointed to both marine and freshwater fish. Given the site location in central Alaska, far away from the ocean, the researchers concluded the marine species must have been salmon, which migrate from the ocean into rivers each year to spawn on gravel beds.
"DNA analysis of chum salmon bones from the same site on the Tanana River had previously confirmed that fish were part of the local indigenous diet as far back as 11,500 years ago," UAF said in a statement.
Read more at Discovery News
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