Wednesday, September 29, 2004

Decrease in Solar Activity May Have Prompted Human Migration

"Bas van Geel, a biologist from the University of Amsterdam, believes that the Earth's climate took a dramatic turn about 2,800 years ago, due to a quiet period in the Sun's activity, making the tropics drier and the mid-latitudes colder and wetter. Previously damp areas, like parts of the Netherlands, became flooded and uninhabitable, while very dry, desert-like areas, such as southern Siberia, became viable places to live.

Teaming up with archaeologists has enabled van Geel to back up his theory by showing that many people were migrating at this time. Along with Dutch specialists, he has found that farming communities in west Friesland suffered increasing rainfall about 2,800 years ago. They resorted to building homes on artificial mounds, but eventually they were washed out of their farms and had to move to drier places. Meanwhile, work in Cameroon has shown that there was an arid crisis that started at about the same time. This dry patch caused some of the forest to die and savannahs to open up. These openings in the forest made it easier for people to move. Archaeological remains show that farming communities began to migrate inland.

Most recently he has worked with Russian archaeologists to show that, also about 2,800 years ago, the Scythian people took advantage of a wetter climate to explore east and west across the steppe landscapes that lie north of Mongolia. Prior to this, the land had been hostile semi-desert, but the extra moisture turned it into green, grassy steppes, enabling these nomadic tribes to travel towards both China and south-east Europe."