Riding the Kelp Highway -- The Channel Islands Link to the First Americans?

We all know the story of how people first came to the Americas, right?  Well, maybe not. Research published in the last 10-15 years has suggested that our old view of human colonization from Asia is wrong - and studies of human prehistory on the Channel Islands could help us understand how this colonization progressed.

From SFU Museum of Archaeology and Ethnology

The traditional view of how humans came to the Western Hemisphere - the one I learned in school - is that humans migrated from present-day Russia by crossing a land bridge formed in the Bering Sea during the ice ages. They spread southward throughout the continent, traveling along an ice-free corridor between two ice sheets. They are called the Clovis after the New Mexico site where their stone tools were first found. The oldest Clovis stone points are dated to about 13,000 years before present*. Archaeologists hypothesize that the Clovis spread from North America to South America over a relatively long period of time, with older remains in the north and more recent remains in the south.

Studies of other archaeological sites call this hypothesis into question.  Archaeological sites along the coasts of Chile were dated to about 14,000 years before present -- too old to be explained by a Clovis-first colonization of the Americas. There are additional sites across the Americas that are as old or older than Clovis sites and that lack Clovis-style artifacts.

It seems likely then that the Clovis arrived in the Western Hemisphere after it was already populated by humans making the trek from the East. The Clovis, or at least their spear points, then spread very quickly across the continent.

Based on archaeological evidence from coastal areas, some archaeologists have proposed a competing hypothesis for the initial peopling of our continent: that colonists traveled by boat along the coast from present-day Russia to coastal sites along North America. This hypothesis does not require that a terrestrial connection existed between the two continents. Archaeological sites on the relatively undisturbed Channel Islands are particularly useful in testing this hypothesis.

Archaeology on the Islands

Six of the islands have supported permanent human settlements: San Miguel, Santa Rosa, and Santa Cruz Islands in the north; Catalina, San Nicolas, and San Clemente in the south. Anacapa and Santa Barbara Islands lack permanent sources of water and are too small for humans to live there year-round; they were visited by these early sea-faring people, but only for hunting and gathering food or as waypoints between the larger islands.

Most archaeological research has focused on the northern islands.  While none of the Channel Islands are highly developed, the northern Channel Islands probably receive more archaeological attention because they are managed by the National Park Service, rather than private owners (like Catalina) or the US military (like San Clemente and San Nicolas).

Channel Islanders didn't live on four islands 13,000 years ago -- they lived on one.  When sea levels were low during the Ice Ages the Northern Channel Islands formed on "super" island, Santarosae. As the ice sheets melted, sea level rose and the single island was divided into the four modern-day islands. Archaeological sites on different modern-day islands are separated by water, but when they were inhabited, all sites were part of one single land mass.

Archaeologist always have to rely on glimpses into the past, using trash heaps (euphemistically called "middens"), lost villages, cemeteries, and bodily remains to piece together our unwritten human history. Coastal archaeologists have it even harder -- sea level rise since the end of the last glaciation has destroyed the majority of coastal archaeological sites.  Even though most island archaeological sites have been lost to the ocean over the past 10,000 years, we have as much or more evidence for human occupation of the Islands than for anywhere else in North America.  

Why do some archaeologists think that the Channel Islands were colonized by the first Americans?

The oldest evidence of humans on the islands, from a site called Arlington Springs, date from about 13,000 years ago. That is at least as old as the earliest dates for Clovis culture elsewhere in the Americas. The oldest remnants of human settlements are found today on Santa Rosa and San Miguel Islands. Arlington Springs is on Santa Rosa Island. Other sites like those at Daisy Cave and Cardwell Bluffs on San Miguel Island have also provided great insight into prehistoric island life.

Early islanders were clearly people of the sea. They traveled on the water and they lived off the ocean. They ate seafood -- mussels, abalone, black turban snails, giant chitons, crabs, and occasionally marine mammals and seabirds. The oldest fish hooks and fish gorges in North America (along with thousands of fish bones) have been found in Daisy Cave. They probably traded stone tools with mainland populations, which were always separated by the Santa Barbara Channel.

Given the maritime lifestyle of the societies who lived on the islands and the age of the human remains and tools found there, perhaps it is true that the first Channel Islanders were the first North Americans.

Stone tools found on Santa Rosa Island
reported in Erlandson et al. 2011

*Dating of archaeological materials from this time period is done with radiocarbon dating.  The long and the short of this is that researchers obtain an age for the object (a bone, for example) in "carbon years before present", which is not exactly equal to calendar years.  To convert a carbon year estimate to a calendar year estimate, they use any of a number of calibration techniques.  Not all calibration techniques are equal and not all carbon dates are converted to calendar years...  so you can't always just look at a date and know how it compares to other dates. I tried to be consistent in this post, but please be aware that the dates I report might not line up perfectly with other dates you see.

Sources and Further Reading

Simon Fraser University Museum of Archaeology and Ethnology in British Columbia has a great webpage about the peopling of the Americas, including information about Clovis culture, land vs. sea migration, Channel Island sites, and a discussion of radiocarbon vs. calendar dates.

Braje, TJ et al. 2010. Channel Islands National Park Archaeological Overview and Assessment. Department of the Interior, National Park Service. Available for download here.

Curry, A. 3 May 2012. Coming to America. Nature 485: 30-32.

Erlandson, J. M. et al. 2011. Paleoindian seafaring, maritime technologies, and coastal foraging on California's Channel Islands. Science 331: 1181-1185. See the commentary by Balter on p. 1122.

Waters, M. R. and T. W. Stafford, Jr. 2007. Redefining the age of Clovis: Implications for the peopling of the Americas. Science 315:1122-1126. There is a commentary by Charles C. Mann on p. 1067 of the same issue. A later comment by Haynes, et al. Science 317: 320b brings into question some of the interpretations and assumptions made by Waters and Stafford.  It's fun to watch scientists disagree -- that's the scientific process at work!

For some insight into the debate about how humans got to the Western Hemisphere, see this editorial from Nature. The debate is an example of the self-correcting nature of science - and shows that scientists are people too.

A 2006 BBC story outlines the then-current view on coastal migration by Jon Erlandson, a Channel Islands archaeologist. A 2011 story by The Oregonian summarizes some later work.