Coastal migration (Americas) facts for kids
The coastal migration hypothesis is a big idea about how the first people arrived in the Americas during the last major Ice Age. It suggests that people traveled by boat along the coast. They might have moved from the Kuril Islands near Asia, along the coast of Beringia (a land bridge that existed then), and down the coasts of Alaska and British Columbia. From there, they could have continued all the way to Central and South America.
Another main idea is that people traveled only through inland routes. This means they walked through an "ice-free corridor." This corridor was a path between two huge ice sheets during the Ice Age.
New discoveries have made the coastal migration idea stronger. For example, scientists found clues in caves on Vancouver Island. These clues suggest that the climate there was warm enough for people to live 16,000 years ago. This was when the huge ice sheets were still very big. Even with this new information, scientists still discuss and debate this hypothesis.
Some researchers believe that people traveled along the coast from Alaska to the Pacific Northwest. This happened before the Clovis culture people moved south through an ice-free path. The Clovis people might have followed later. This was when the ice sheets melted and opened up new routes between inland and coastal Alaska.
In 2017, archaeologists found something amazing on Triquet Island. A team from the University of Victoria discovered a hearth (an ancient fireplace). It was between 13,613 and 14,086 years old! This discovery supports the local Heiltsuk Nation's oral stories. Their stories say the island was lived on during the Ice Age. This makes it one of the oldest known settlements in North America.
Some archaeologists thought the Clovis people moved south from Alaska through an ice-free corridor. This corridor was between modern British Columbia and Alberta. However, newer studies of Clovis sites in Alaska suggest something different. They show that Clovis tools and ways of life actually moved *from the south* into Alaska. This happened after the ice sheets melted about 10,500 years ago.
The oldest dog remains in North America were found in Lawyer's Cave in Alaska. Scientists used radiocarbon dating to find out they are 10,150 years old. Genetic studies suggest this dog's family separated from Siberian dogs about 16,700 years ago. This timing fits well with the idea that a coastal route opened up into North America around then.
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Why Finding Old Coastal Sites is Hard
It's tough to figure out exactly when the first coastal migrations happened. This is because many early settlement sites are now underwater. The sea level rose a lot as the huge ice sheets melted after the Ice Age.
Sites like Ground Hog Bay in Southeast Alaska (10,200 years old) and Namu in British Columbia (9,700 years old) show early settlements. These places are above today's sea level. But people likely traveled by boat when the sea level was lower. At that time, the coast was still covered in ice. To truly understand these early journeys, we need to imagine the land and food resources available back then.
Clues from Southeast Alaska and Haida Gwaii (Queen Charlotte Islands) in British Columbia give us hints about food and land. Scientists have found several sites on Haida Gwaii that are over 9,000 years old. The oldest human remains found on the west coast of North America are from On Your Knees Cave. This cave is on Prince of Wales Island in Southeast Alaska. The person was a young man who died about 10,000 years ago. Studies show he ate mostly seafood.
These findings suggest that people lived in these areas when the sea level was lower. This means there could be many ancient sites hidden underwater along the old coastlines of Haida Gwaii and Southeast Alaska.
Between 13,000 and 10,500 years ago, Haida Gwaii was more than twice its current size. A quick rise in sea level between 11,000 and 9,000 years ago flooded much of this land. So, any evidence of the very first people on Haida Gwaii's ancient coast would now be deep underwater. Older sites found near today's shorelines would have been about 15 miles (24 km) from the coast back then.
Scientists have found ancient stone tools in the areas that are now covered and uncovered by tides along the Haida Gwaii coast. This suggests that people lived there a very long time ago. These discoveries support the idea of early coastal migration.
The "Kelp Highway" Theory
This idea helps explain how humans could have settled the Americas even before the ice sheets fully melted. The "Kelp Highway" theory suggests that people traveled and settled in northern coastal areas. These areas, especially the northern Pacific Rim, had very rich ecosystems.
The many types of kelp in the Pacific Rim are super important for life there. They create huge underwater forests that support all kinds of creatures. These include marine mammals, shellfish, fish, seabirds, and edible seaweeds. These resources would have been a perfect food source for early hunter-gatherers traveling along the coast.
While we know how great kelp forests are today, it's hard to know exactly where they were during the Ice Age. But scientists have made good guesses about where these ancient kelp forests might have grown.
Clues from Archaeology and Geology
Archaeological sites from the Pacific Northwest down to Baja California offer more proof for the coastal migration theory. In California, sites like Borax Lake, the Cross Creek Site, and the Santa Barbara Channel Islands show human settlement between 12,000 and 7,000 years ago. The Arlington Springs Man is a famous discovery of 10,000-year-old human remains on the Channel Islands. Scientists found remains of marine shellfish, which are linked to kelp forests, at these sites.
In South America, the Monte Verde site in Chile shows human presence as early as 12,500 years ago. This suggests that people migrated south along the coast. The ice sheets would not have melted enough for inland travel at that time.
More evidence comes from studies showing that the Pacific coastal corridor became biologically rich after the ice melted. This means there was plenty of food and an easy route for early people to travel.
Animal Bones Tell a Story
Animal bones found along the Northwest coast also support the idea of a rich coastal environment. These bones show there was enough food to support early coastal travelers. Goat bones as old as 12,000 years have been found on Vancouver Island. Bear bones dating back 12,500 years were found in the Alexander Archipelago in British Columbia. Even older bones of black and brown bears, caribou, sea birds, fish, and ringed seals have been found in Alaskan caves. This means there were enough land and plant resources to support large animals, and likely humans too.
Ancient Boats and Sea Travel
Scientists believe the coast was settled before 13,000 years ago. This idea is partly based on evidence of boats from Japan from before that time. In Indonesia, ancient food remains show that people were fishing offshore between 35,000 and 40,000 years ago. This would have required boats.
People who lived by the sea were very good at moving around the many islands off East Asia during the late Ice Age. This helped spread boat-making skills and sea travel knowledge. As the climate warmed after about 16,000 years ago, it might have encouraged people to travel by sea. They could have moved up the Kurile island chain towards North America. This warming brought a nicer climate and more food in the ocean.
No actual boats have been found at early Pacific Coast sites. This is probably because wood and other organic materials don't last long. Also, many coastal areas are now underwater. But we can still guess that people traveled by water. We find human-made tools on islands that could only be reached by boat.
There's also an old story from the Heiltsuk people (also known as Bella Bella). It was written down in 1898. The story says, "In the beginning there was nothing but water and ice and a narrow strip of shoreline." Some people think this story describes the Northwest Coast during the last time the ice sheets melted.
Traveling South
Further south, California's Channel Islands also show signs of early boat travel. On Santa Rosa and San Miguel islands, scientists found 11 sites from the end of the Ice Age. This includes the Arlington Springs Man site, which is about 11,000 years old. Daisy Cave was lived in about 10,700 years ago.
It's important to know that the Channel Islands were never connected to the mainland. So, the people who lived there during the time of the Clovis culture must have had strong boats to reach them. The Channel Islands also have the oldest fishhooks found in the Americas. These bone hooks are between 8,500 and 9,000 years old.
Even further south, the Monte Verde site in Chile is now accepted as the earliest settlement in South America. It dates back at least 14,500 years ago. This strongly suggests that people migrated through northern coastal areas before that time. At Monte Verde, scientists found the remains of nine types of seaweeds, including kelp.
Western Stemmed Tradition: Ancient Tools
The early settlers on the Channel Islands used finely made stone tools called "stemmed points." They also used crescent-shaped chipped stones. These tools are similar to those found at "Western Stemmed Tradition" (WST) sites across western North America.
These ancient stemmed points have been found at many sites. For example, at Buttermilk Creek in Texas, these tools are dated to about 13,500 to 15,500 years ago. At the nearby Gault site, stemmed points from about 16,000 years ago were found below Clovis tools.
At Paisley Caves in Oregon, WST points are dated to about 12,700 to 13,000 years ago. Similar dates have been found at Cooper's Ferry in Idaho. At Meadowcroft Rockshelter in Pennsylvania, a tool similar to WST points is about 14,000 years old.
In Mexico, a stemmed point was found with mammoth bones at Santa Isabel Iztapan. Other stemmed points were found nearby with butchered mammoth bones. These dates are similar to the ones mentioned above.
South America also has a long history of using stemmed points. They are known as 'El Jobo points' there. These points were found at Monte Verde, Chile, and were used as early as 14,200 years ago. El Jobo and 'Stemmed Fishtail points' became common across South America about 13,000 years ago.
On the Channel Islands, scientists have found several early shell middens (ancient trash heaps). These sites are near sources of chert, a type of rock used to make stone tools. These quarry and workshop sites are between 10,000 and 10,500 years old. They contain crescent tools and finely made stemmed points. These tools were likely used to hunt birds and sea mammals.
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