人類の進歩を”海”から見よう

BBCからのニュースですが、人類の進化の歴史、特に新大陸の発見に関してはほとんど陸からの視点でのみ論理化され、今まで海からの視点で語られることが少なかったそうです。しかし、近年になり、その考えが変わりつつあります。

アフリカから進出した人類はインド洋づたいに50,000年前には船や筏を使いオーストラリアに到達していました。また、アメリカへの道ですが、海岸の豊富な資源、オットセイ、様々な魚、そして昆布などを捕獲しながら活動範囲を広げていったと考えることが可能です。北の海の海岸に住む哺乳類などは捕獲が比較的簡単で、また栄養(脂)が豊富です。ケルプ(海草)もまた内陸の資源に比べ豊富です。

海岸の遺跡から釣り針や縄などが最近になり出土していますが、丘の考古学資料に比べ数が少ないのは事実です。しかし、海進の結果遺跡が破壊されたことや、残っていても注意をして探さないと見つけにくいことがあります。また、海岸の開発で壊されてしまうこともあるでしょう。

人々に関心がないとこれらの貴重な遺跡は簡単に破壊されてしまいます。現実にいくつの遺跡が開発により破壊されているのか定かではありません。ちょっとした関心があり、開発の際に注意をしていれば発見は可能です。このようにして発見された遺跡には陸上とは全く違った価値と可能性が秘められています。

Early humans followed the coast
By Paul Rincon
Science reporter, BBC News

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.

Anthropologists have long regarded the exploitation of marine resources as a recent development in human history, and as peripheral to the development of civilisation.

This view has been reinforced by a relative lack of evidence of ancient occupation in coastal areas.

But that view is gradually changing; genetic studies, for example, 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.

“The story of human evolution and human migrations has been dominated by terrestrial perspectives,” the University of Oregon researcher told BBC News.

“I grew up on the coast and I always thought this didn’t make much sense. Coastlines are exceptionally rich in resources.”

Ancient artefacts

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.

The big elephant seals weigh over 300lbs,” he explained. “It has always seemed to me that these were a resource that early humans would not want to miss.”

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.

“The preservation is superb, so we interpreted the cordage as ‘cut-offs’ from the manufacture and maintenance of nets, fishing lines, and other maritime-related woven technologies,” Professor Erlandson said.

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.

‘Kelp highway’

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.

At the height of the last Ice Age, a land mass called Beringia would have connected North-East Asia to North America.

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”.

He added: “I think the peopling of the New World was much more complex than has traditionally been viewed. I think it probably involved maritime and terrestrial migrations.”

Jon Erlandson was speaking at the Calpe Conference 2006 in Gibraltar.

引用元:http://news.bbc.co.uk/2/hi/science/nature/5398850.stm

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