Learning how to live off the sea may have played a key role in the expansion of early humans around the globe. After leaving Africa, human groups probably followed coastal routes to the Americas and South-East Asia. Professor Jon Erlandson says the maritime capabilities of ancient humans have been greatly underestimated. He has found evidence that early peoples in California pursued a sophisticated seafaring lifestyle 10,000 years ago.
     Genetic studies suggest a major early human expansion out of Africa occurred along the southern coastline of Asia, leading to the colonisation of Australia 50,000 years ago. Shifting sea levels since the last Ice Age, combined with coastal erosion, would have erased many traces of a maritime past, Professor Erlandson explained.
     Professor Erlandson has carried out extensive excavations on San Miguel Island, off the coast of California, which is known to have been inhabited at least 13,000 years ago. About 100,000 seals and sea lions of six different species live on the island. These slow-moving sea mammals would have been easy prey for the island's early human inhabitants. One of the digs, at Daisy Cave, on San Miguel Island, has yielded scores of bone "gorges", a form of fish hook. The gorges were covered with bait to be swallowed whole by fish, which were then reeled in. These are between 8,600 and 9,600 years old and are associated with more than 30,000 fish bones. They are the oldest examples of such artefacts in the New World. The researchers have also recovered fragments of knotted "cordage" - woven seagrass - that might have been used to make fishing nets. These delicate items were preserved by pickling under layers of ancient cormorant dung. At other sites, the researchers have found barbed points that were most likely used for hunting sea mammals - possibly sea otters. They also unearthed examples of 9,000-year-old basketry as well as 8,600-year-old shell bead jewellery.
     The findings from Daisy Cave could be consistent with the idea that some of America's first colonists followed a coastal migration route from Asia. Conquering the cold waters of the northern Pacific would have required advanced seafaring skills as well as an ability to successfully exploit marine resources. Traditionally, the first Americans were thought to be big game hunters, who marched from Siberia across the land bridge to Alaska. Then, they were thought to have travelled south through the Canadian Arctic via an 'ice-free corridor' that emerged in the central US. But the earliest signs of human occupation from the ice-free corridor date to 11,000 years ago, while California's Channel Islands are now known to have been inhabited at least 13,000 years ago. Professor Erlandson has come up with an alternative theory that maritime peoples from Asia followed forests of kelp to the New World.
     Kelp Forest would have hugged the coastline from Japan up through Siberia to Alaska and down along the Pacific coast of North America. This marine plant grows in rocky, nearshore habitats and cold water up to 20C. It creates rich ecosystems, providing habitats for seals, sea otters, hundreds of fish species and shellfish. These could have been important sources of food and other resources such as skins for early peoples. However, the professor of archaeology says "actually proving such a migration took place is a very difficult thing to do because of sea level changes and coastal erosion".

Source: BBC News (5 October 2006)