Naked Archaeology

I recently came across an old episode of Naked Archaeology--actually, I think it's the very first podcast--which happens to discuss Peru's historical ecology. I'm having trouble embedding it, so follow this link and scroll down to the bottom of the page if you want to listen.

The first segment features David Beresford-Jones, an archaeobotanist who studies the collapse of Nazca civilization. The prevailing explanation for the Nazca's demise is El Nino flooding. However, Beresford-Jones feels that it is wrong to ascribe cultural change to climatic events entirely. In an article in Nature, he notes that "...this [explanation] is not satisfying based on what we know about human culture. It paints a picture of culture sitting there, not changing, hit by events over which they have no control. But Native Americans did not always live in harmony with their environment."

Beresford-Jones and his colleague Alex Chepstow-Lusty have analyzed the pollen left by the Nazca's landscape at different time periods. They found that early in Nazca history, most pollen was left by riparian trees, like huarango, indicating that their land was heavily wooded. Over time, though, pollen sources were mostly agricultural (maize and cotton), indicating that the Nazca cut down their woodlands to make way for farmland. Unfortunately, these trees had a major impact on the local biodynamics: the huarango trees lowered floodwater velocity, allowing it to soak into the ground and replenish the water table. Deforesting the landscape allowed for El Nino to hit the floodplain directly and erode the farmland, rather than recharge groundwater that was essential to future crop viability.