Rise and fall of farmers

23:17, Nov 19 2012

The first farmers who swept into Europe 6000 to 7000 years ago may have grown too big for their britches - or animal skins - too fast.

A new study of archaeological sites across Western Europe highlights a strikingly consistent pattern in Neolithic farmers' communities: Their populations grew too big, too quickly, and crashed right after they peaked.

"We can see a dramatic history of booms and busts," archaeologist Stephen Shennan of University College London (UCL) reported in a talk at the 111th meeting of the American Anthropological Association in California.

Researchers have long assumed that as the first farmers settled down in Europe, life was more stable for them than for the nomadic foragers and fishers they had displaced.

Cultivated plants and animals were a secure source of food, the reasoning went, allowing the farmers to bear more babies and put down deep roots.

An overall picture emerged in which farming populations grew gradually until modern times.


"It has been generally assumed that population slowly increased, in line with long-term continental and global trends," Shennan said.

No studies, however, had looked closely at what happened to population growth locally in different regions of Europe after the first farmers arrived.

Working with evolutionary geneticist Mark Thomas at UCL, Shennan developed a statistical method to trace the rise and fall of population numbers by using calibrated radiocarbon dates at archaeological sites in Europe.

They reasoned that the more dates for Neolithic settlements in a region, the higher the population (after correcting for different numbers of dates from different archaeological sites).

Once they used clusters of dates to track patterns of population growth and decline at archaeological sites in Europe, they calibrated their method by studying patterns in the types and dates of pollen found at the sites, which reflect when farmers cleared land of trees to grow crops.

The two records of population growth matched, Shennan said.