Before European conquerers arrived, large areas of the Amazon River basin had been cleared away to make room for a network of towns and villages.
The findings raise big questions, says Susanna Hecht of the University of California in Los Angeles.
For starters, it forces a rethink of the long-held assumption that these parts of the Amazon were virtually empty before colonisation. What's more, it shows that the large populations that did inhabit the region transformed the landscape.
"What we find is that what we think of as the primitive Amazon forest is not so primitive after all," Heckenberger told New Scientist. "European colonialism wasted huge numbers of native peoples and cleared them off the land, so that the forest returned."
I'm gonna plug 1491 again...the story above isn't news to anyone who's read this book, which argues that there was plenty going on in the New World before Columbus, et. al. arrived.
At PopTech a few weeks ago, Lester Brown, who has been a leading advocate of environmentally sustainable development for almost 30 years, spoke about the impact of the increasing production of ethanol. As more corn gets used for making automotive fuel, that reduces the amount of grain available for food production. As demand rises, so will the price...no matter what people are using the corn for, be it fuel or food. The countries that will really suffer in this scenario are those that import lots of grain for food.
When Brown said this, I immediately thought of Mexico. When you consider the food culture of Mexico, one of the first things to mind is corn. Corn (maize) was likely first domesticated in Mexico and remains the cornerstone of Mexican cuisine; in short, corn is far more Mexican than apple pie is American. In 1491, his excellent book on the pre-Columbian Americas, Charles Mann tells us that despite corn's high status, Mexico is increasingly importing corn from the United States because it's cheaper than local corn:
Modern hybrids are so productive that despite the distances involved US corporations can sell maize for less in Oaxaca than can [local farmer] Diaz Castellano. Landrace maize, he said, tastes better, but it is hard to find a way to make the quality pay off.
Those great tortillas you had at some local place while on vacation in Mexico? There's an increasing chance they're made from US corn. Mmm, globalizious! Of course, Mexican farmers are getting out of the farming business because they can't compete with the heavily subsidized US corn and Mexico is losing control over one of their strongest cultural customs. Now that ethanol is changing the rules, there's a bidding war brewing between Americans who want to fill their gas tanks and Mexicans who want to feed their children. Odds are the tanks stay fuller than the stomachs.
For reference, here's what increasing ethanol production has done to the price of corn over the past three months:

And that's despite a fantastic US corn harvest. The graph is from this article in the WSJ, which contains a quick overview of the effects that the growing ethanol industry might have.
Short positive review of 1491: New Revelations of the Americas Before Columbus (@ Amazon). Thumbed through it at the bookstore yesterday and it did look good...but I've got too many books in my queue already.