A secluded “lost world” off the coast of California may force historians to rethink how the first people reached the Americas.
Across the Channel Islands, researchers have found 13,000-year-old human remains, traces of early settlements and clues that some of the continent’s first inhabitants may have arrived by sea instead of moving through an inland corridor between ice sheets.
If that interpretation proves right, it would challenge the long-dominant view that the earliest Americans crossed from Siberia over a land bridge before heading south through an ice-free passage in what is now western Canada.
The alternative theory argues that Ice Age travelers navigated the Pacific coast by boat, following a rich coastal route often called the “kelp highway” and establishing themselves in places such as the Channel Islands thousands of years ago.
The island chain has also produced pygmy mammoth bones and unusually well-preserved archaeological sites, giving scientists a rare window into life during the Ice Age. Researchers have described the area as a landscape where ancient environments and human history appear to have been preserved in place.
Experts say the growing body of evidence points toward an overlooked seafaring migration that could reshape what is known about the earliest Americans. Many believe some of the most important clues may still be buried on the islands or hidden beneath the surrounding waters.
Scientists and archaeologists have investigated the Channel Islands for more than 100 years, with landmark finds — including the remains known as Arlington Springs Man — uncovered during mid-20th-century excavations.
A new documentary, released June 30 on the YouTube channel Timeline, is now drawing renewed interest to those discoveries and to the unresolved mysteries still concealed across the islands and their offshore depths.
The eight California Channel Islands lie in the Pacific Ocean off Southern California, stretching from Point Conception near Santa Barbara to south of Los Angeles. Pictured is Santa Cruz, one of the islands
Not all archaeologists agree that the Channel Islands provide definitive proof of a maritime migration.
While many researchers now accept that people were present in the Americas before the Clovis culture, experts continue to debate exactly when the first settlers arrived and whether they traveled by sea, by land, or through a combination of routes.
The eight California Channel Islands lie in the Pacific Ocean off Southern California, stretching from Point Conception near Santa Barbara to south of Los Angeles.
Author Frederic Caire Chiles, who has a PhD in history from the University of California at Santa Barbara, said in the film: ‘They are the trace of a vanished world.’
The four northern islands – San Miguel, Santa Rosa, Santa Cruz and Anacapa – were not always where they are today.
Geologists say they were once located much farther south, near present-day San Diego, before tectonic forces slowly carried them north and rotated them by around 110 degrees.
The islands have become a treasure trove for archaeologists because their ancient deposits have remained remarkably undisturbed, preserving evidence erased elsewhere by rising seas and thousands of years of human activity.
Among the most significant discoveries is Arlington Springs Man, human remains found on Santa Rosa Island and eventually dated to at least 13,000 years old.
Pictured is the site where the Arlington Springs Man was discovered
Bones of a man were uncovered 37 feet below waterlaid sand, mud and gravel sediments in 1959.
Dr Thomas Stafford, a geologist and radiocarbon dating expert, said that after testing the remains in 2001, the bones were the oldest dated human skeletal remains in North America.
The discovery was particularly important because the remains are roughly the same age as the Clovis culture, long considered the first people to inhabit the Americas.
But unlike the Clovis sites found inland, Arlington Springs Man was discovered on an offshore island, suggesting some of North America’s earliest inhabitants may already have been skilled seafarers.
The Clovis people, known for their distinctive fluted spear points, were once thought to have entered North America through an ice-free corridor in Canada.
The Channel Islands discovery raised the possibility that another group may have reached the continent by boat, following the Pacific coastline instead.
The islands have also yielded the bones of pygmy mammoths and remarkably preserved archaeological sites that offer an unprecedented glimpse into Ice Age life
Five of the islands have been established as a national park
But the Channel Islands presented a puzzle. People living on an offshore island 13,000 years ago would have needed boats to get there, suggesting seafaring technology existed much earlier than previously believed.
Some researchers have argued that the ice-free corridor may not have been fully open or ecologically viable when the first people reached the islands, raising the possibility that they arrived by sea instead.
Researchers call this the ‘kelp highway’ hypothesis. Dr John Johnson, curator of anthropology at the Santa Barbara Museum of Natural History, said: ‘All the way from Japan to Baja California, there are kelp forest ecosystems that have very similar suites of animals.
‘This connects with the whole idea of a coastal migration, an ancient coastal migration where people would have been using watercraft and going around glaciers when they encountered them and working their way down until they came to California.’
‘People showed up on this island 13,000 years ago or thereabouts and evolved through time into the group we know as the Chumash.’
The Chumash ancestral homeland spans California’s central and southern coast and includes the four northern Channel Islands.
During the Ice Age, mammoths roamed what was once a single larger island made up of today’s northern Channel Islands before evolving into dwarf versions known as pygmy mammoths.
Pictured is a view from across Santa Rosa Island
The species vanished around the same period humans appeared on the islands, fueling speculation that some of North America’s earliest inhabitants may have encountered, and perhaps hunted, the miniature elephants.
For thousands of years, the islands became the homeland of the ancestors of the Chumash people, who developed sophisticated maritime communities and traded shell bead money with mainland groups.
The islands were forever changed after Portuguese explorer Juan Rodríguez Cabrillo became the first European to reach California in 1542.
‘This was the furthest projection of Europe into a world that they knew nothing about,’ one historian explained.
Disease, colonization and social upheaval eventually devastated Indigenous communities and led to the abandonment of the islands.
One of the most remarkable stories to emerge from this period is that of the ‘Lone Woman of San Nicolas Island,’ later immortalized in the novel Island of the Blue Dolphins. She survived alone on the island for about 18 years before being rescued in 1853.
Today, scientists believe the islands still hold countless secrets beneath their rugged landscapes and surrounding waters.
During the Ice Age, sea levels were hundreds of feet lower, meaning areas that are now underwater were once dry land that may have been inhabited by some of America’s earliest people.
