Nov. 2: British archaeologists have found an example of extreme climate change and a bloody resource war in the disappearance of an ancient South American civilisation.
The Nasca, who once flourished in the valleys of south coastal Peru and disappeared around 1,500 years ago, helped to cause their own demise by damaging the fragile ecosystem, according to a study led by the Cambridge University.
The Nasca civilisation, best known for the famous "Nazca Lines," or giant geoglyphs etched into the surface of the vast, empty desert plain that lies between the Peruvian towns of Nazca and Palpa, collapse around 500 AD.
Using plant remains, the team of researchers led by Cambridge University’s Dr David Beresford-Jones, found evidence that over the course of many generations, the Nasca cleared areas of forest to make way for their own agriculture. The huarango tree, which once covered what is now a desert area, was gradually replaced by crops like cotton and maize.
The huarango tree was a crucial part of the desert’s fragile ecosystem, which enhanced soil fertility and moisture and helped to hold the Nasca’s narrow, vulnerable irrigation channels in place. Eventually, so many trees were cut down that the arid ecosystem was irreversibly damaged.
The devastation was completed by a mega-El Niño, which caused floods to hit the region at around that time. After this, infant mortality rose and average adult life expectancy fell and the crops disappeared leading to a severe drought, leading to disappearance of the civilisation.
"These were very particular forests," Dr Beresford-Jones said. "The huarango is a remarkable nitrogen-fixing tree and it was an important source of food, forage, timber and fuel for the local people. Furthermore, it is the ecological ‘keystone’ species in this desert zone, enhancing soil fertility and moisture, ameliorating desert extremes in the microclimate beneath its canopy and underpinning the floodplain with one of the deepest root systems of any tree known. In time, gradual woodland clearance crossed an ecological threshold - sharply defined in such desert environments - exposing the landscape to the region’s extraordinary desert winds and the effects of El Niño floods."
