Wherever people gather en masse, so does their trash. Even large-scale events with good environmental intentions can result in a heap of rubbish. To serve as a reminder to tread lightly, here are 10 of the world's dirtiest events.
Photo gallery: Until 1963, when Jane Goodall published her work on wild chimpanzees using tools, most scientists believed that tool use was a uniquely human trait. We're finally beginning to know better.