Until recently, the "coastal migration theory" was not accorded much importance by most scholars. However, new discoveries have moved it to the forefront of debate on the origins of the First Americans. It is now known that seafaring peoples living in the Ryuku Islands and Japan near the height of the last glacial period (about 35,000 to 15,000 years ago) adapted to cold waters comparable to those found today in the Gulf of Alaska. From Japan, they may have migrated northward through the Kurile Islands, to the southern coast of Beringia (ancient land bridge between what is now Siberia and Alaska), and into the Americas.
"The coastal migration theory has yet to be proven with hard evidence, but we have been finding earlier and more widespread evidence for coastal settlement around the Pacific Rim," said Jon Erlandson, professor of anthropology and director of the Museum of Natural and Cultural History at the University of Oregon and the study's lead researcher. "The fact that productive kelp forests are found adjacent to some of the earliest coastal archaeological sites in the Americas supports the idea that such forests may have facilitated human coastal migrations around the Pacific Rim near the end of the last glacial period. In essence, they may have acted as a sort of kelp highway."
Kelp forests are some of the world's richest ecosystems. They are found from Japan to Baja California and to South America's west coast. They would have provided a similar assortment of food resources--including shellfish, fish, sea mammals, and seabirds--along thousands of miles of the North Pacific coast, and also reduced wave energy for people in boats. These people also would have had access to a variety of land resources. In contrast, people migrating through the interior would have had fewer options and would have had to pass through much more varied landscapes, including tundra, boreal and tropical forests, and deserts.
"This study is a unique example of collaboration between coastal archaeologists and marine biologists" Erlandson said. "I've worked on many early sites near kelp forests from Alaska to California, but I never realized similar habitats were present around much of the Pacific Rim. Combining our very different perspectives provided an opportunity to reach insights that none of us would have attained alone."
The "kelp highway hypothesis" first crystallized among an interdisciplinary group working at the National Center for Ecological Analysis and Synthesis. The study's other researchers include: Michael Graham of Moss Landing Marine Laboratories; Bruce Bourque of Bates College; Debbie Corbett of the U.S. Fish and Wildlife Service in Anchorage, Alaska; James Estes of the U.S. Geological Survey and the University of California-Santa Cruz; and, Robert Steneck of the University of Maine.