Examples of societies collapsing through force of habit

The Guardian (sentence in bold was omitted), 25 November 2015:

History provides us with several examples of societies collapsing through force of habit, including an addiction to meat (Tax on meat not too hard to swallow, study suggests, 24 November). When the Vikings colonised Greenland in the 10th century, they were determined to preserve their tribal customs, which included raising cattle. Because pasture was limited and the growing season only three months, virtually all of the land was used to grow silage to see the cattle through the winter. After nine months indoors, cattle were so weak they had to be carried out to pasture. The irony is that they were surrounded by a plentiful source of protein in the oceans, but another Viking custom in Greenland was a refusal to eat fish.  When the climate turned harsher this agricultural system became unsustainable and the Vikings of Greenland perished. I wonder whether the modern world will fare any better as we career towards climate catastrophe.

Dr Robin Russell-Jones
Stoke Poges, Buckinghamshire