On: "Amazonian dark earth" was the work of ancient hum...

[hinkley]

I still have an imaginary bet running with myself that we will eventually discover that Terra preta was the result of some form of pit roasting technique. Dig a hole in a different spot for each celebration.

[SantalBlush → hinkley]

The simplest explanation is that they were just as intelligent and capable as other people of their time, and figured out a way to improve their soil.