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Another reason why a society may fail to anticipate a problem is that they may have prior experience – but it has been forgotten. A society with little writing or records isn't going to preserve oral memories of something that happened long ago.

The Classic Lowland Maya eventually succumbed to a drought about in around the year 800. There had been previous droughts in the Maya realm, but they could not draw on that prior experience because, although the Maya had some writing, their records merely preserved the history of royal conquests, not droughts.

Mayan droughts recur at intervals of 208 years, so the Maya in 800 – when the big drought struck again – did not, and could not, remember the drought of 592.

In modern literate societies, even though we have writing, that does not mean we can draw on prior experience. We too tend to forget things. People of the developed world today – and particularly Americans – behave as if they've forgotten about the 1973 oil crisis.

For a year or two after the crisis, Americans avoided gas-guzzling vehicles; but then quickly forgot that knowledge – despite having a mass of newspaper articles, books, historical records, and lengthy television footage of the impact of the oil crisis.

In the 1960s the city of Tucson in Arizona went through a severe drought, and the citizens swore that they would manage their water better; but within a decade or two, Tucson had fallen off the rails and reverted to its water-guzzling ways, even building golf courses.

Then there's 'reasoning by false analogy', another cause for why a society may fail to anticipate a problem before it develops. When humans are in an unfamiliar situation, we fall back on reasoning based on old, familiar situations. That's a good way to proceed if the old and new situations are truly analogous; but can be dangerous if the situations are only superficially similar.

Take Norwegian Vikings who migrated to Iceland from 871 AD. Their familiar homeland of Norway has heavy clay soils ground up by glaciers: those soils are so heavy that, if the vegetation covering them is cut down, they are not blown away.

Unfortunately for the Viking colonists of Iceland, the local soils are as light as talcum powder: Icelandic soil was not a product of glacial grinding, but of the wind dispersal of light volcanic ash from volcanic eruptions. So when the Vikings cleared Icelandic forests to create pasture, the ashen soils blew away. Within a few generations, half of Iceland's topsoil had eroded into the ocean. Other examples of reasoning by false analogy abound.

Societies can also fail to perceive a problem that has actually arrived. The history of collapsed civilisations reveals failures of recognition have at least three distinct causes, all of them relatively common in the world today.

First, a problem may not be noticed because its origins are literally imperceptible. For example, the nutrients responsible for soil fertility are invisible to the naked eye, and have only recently become measurable via chemical analysis.

In Australia, parts of the U.S. south-west, the island of Mangareva in French Polynesia, and many other locations, most of the nutrients had already been leached out of the soil by rainfall before people arrived. When human settlers began growing crops, the remaining nutrients were quickly exhausted and agriculture rapidly failed.

Such nutrient-poor soils often bear deceptively lush-appearing vegetation: it's just that most of the nutrients in the ecosystem are held by the plants rather than the soil, so the nutrients vanish when the vegetation is cut down. There was no way that the first colonists of Australia or Mangareva could have known about soil-nutrient exhaustion before they started clearing vegetation.

A more common reason for failing to perceive a problem is that it may be a slow trend that is hidden by wide fluctuations. The best example is global warming: we now realise that temperatures around the world have been slowly rising for decades, due in large part to changes in the atmosphere caused by humans.

However, it is not the case that the climate each year is 0.17°C warmer than the previous year. Temperature fluctuates widely from year to year: three degrees warmer one summer, then two degrees warmer the next summer, down four degrees the following summer, down another degree the next summer, then up five degrees, and so on. With such fluctuations, it takes a long time to recognise the upward trend.

That's why it was only a few years ago that the last professional climatologist, previously sceptical of global warming, became convinced. Many political leaders still say we need more research. Medieval Greenlanders had similar difficulties recognising their climate was slowly becoming colder, and the Maya of the Yucatan had trouble discerning that their climate was gradually becoming drier.

The term 'creeping normalcy' (or normality) is often used to describe such slow trends buried within noisy fluctuations. If a situation is getting worse only slowly, it is difficult to recognise that this year is worse than last year, and each successive year is only slightly worse than the year before; what you consider 'normal' shifts only gradually and almost imperceptibly. It may take a few decades or a long sequence of such slight year-to-year changes before someone suddenly realises that conditions were much better several decades ago.

The final frequent reason for failure to perceive a problem is 'distant managers', which can often happen in a large society. Administrators can be so far removed – geographically and otherwise – from local conditions that they do not notice changes that might be apparent to someone on the ground.

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