BioEd Online

Necessity is the mother of invention and this adage may be true for the birth of entire civilizations. Extreme changes in the Earth's climate that happened around 3,000 years ago, during which the Sahara Desert became completely arid and the El Nio cycle strengthened, could have kick-started civilizations in some places on Earth, says Nick Brooks of the University of East Anglia in Norwich, UK.

The idea that sudden changes in climate conditions might bring on hard times and spur people to work together, forcing them to build more complex structures for protection and systems for growing food, may sound obvious. But many have argued before that the opposite is true: that only in times of comfort will a group of people take the time to develop civilized cultures.

Brooks hit upon the idea while studying the Garamantian civilization, which grew up in Libya during a period of environmental turmoil. Archaeological remains show that as their verdant paradise became a desert some 3,000 years ago, people started to migrate, congregating around the few remaining lakes.

With everyone living on top of each other with a limited supply of food and water, civilization was born as a means of surviving in these new harder times, Brooks reports in the journal Quaternary International¹. The Garamantians developed new forms of organized agriculture with complex underground irrigation systems, built iconic structures and became more territorial.

Similar changes can be observed all over the world, Brooks told the British Association Festival of Science in Norwich today. The Egyptian empire also became unified at around this time, while large urban societies were also forming in South Asia and China.

The changes might not have been entirely positive, however, Brooks notes. "Life actually got worse for a lot of people," he says. "Inequality and hierarchy increased and most people had to do more hard labour." Hunter-gatherer communities, on the other hand, ran on a consensus basis with no set leaders much closer to today's notions of the democratic ideal.

Climate change has been linked to changes in civilization before: the strengthening El Nio in Peru at this time has previously been blamed for literally washing away a society.

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