POCATELLO – The earliest North American inhabitants were probably more diverse in their food selection than previously thought – think of them as salmon fishermen as well as game hunters – according to a new study published Monday in the “Proceedings of the National Academy of Sciences.”
A team of scientists, including Idaho State University’s Bruce Finney, have documented the oldest use of salmon as a food source in North America, which occurred about 11,500 years ago in Alaska at the Upward Sun Site, the oldest dated site with human remains in Alaska.
The seven scientists – from ISU, University of Alaska Fairbanks, Simon Frazier University and Washington State University – used two powerful tools to make this find: they did DNA analysis to determine that salmon bones found at the site were chum salmon, and they used a mass spectrometer to do stable isotope analysis to determine that these salmon migrated from the ocean up the Tanana River, a tributary of the Yukon River, where the Upward Sun Site is located.
“Through stable isotope analysis we confirmed the chum salmon came from the ocean – isotopes signatures are different in fish from freshwater and the ocean,” said Finney, ISU professor in the Departments of Biological Sciences and Department of Geosciences.
These findings have major implications.
“There was kind of a dogma that early inhabitants were just big game hunters, but this study shows they used a broader range of resources,” Finney said. “This is the earliest recorded evidence for people fishing for salmon (in North America) and changes how scientists think about the food sources used.”
A major implication of the study, Finney said, is that ocean-salmon runs were established when early humans migrated into North America, and since many of the archeological sites that date to the time of early migration are found along rivers, it is possible that salmon were an important food resource. This contrasts to the common view that early humans in North America were primarily hunters of large terrestrial animals such as mammoths.
The study, “Early human use of anadromous salmon in North America at 11,500 years ago,” has already received widespread publicity, garnering stories in the New York Times, Science Magazine, New Scientist and a variety of other media outlets and websites.
“This study demonstrates that people were using salmon as a food source when they were moving from Asia into North America,” Finney said. “It also documents that salmon runs were established in the Tanana River at the time. There is clear evidence they were eating salmon as a major food resource. The predictable annual salmon runs are a nutritious supply of food.”
The Upward Sun Site is located near the extreme end of where salmon migrate up this tributary of the Yukon. The interior of Alaska was not glaciated during the last ice age, which was waning as humans migrated into North America, Finney said. The river was connected to the ocean, where conditions during the ice age likely weren’t as good for salmon as they are now. However, this study confirms there were healthy salmon runs in Alaska at least by the time of deglaciation.