Whenever we talk about our ecological footprint, it's usually a bad news story about some terrible thing humans have done to the environment. Well, not this time. For at least six thousand years until only a couple of hundred years ago, early inhabitants of the Pacific coast ate a lot of clams. And they'd leave the empty shells in big piles called middens. As it turns out, Dr. Andrew Trant from the University of Waterloo has discovered that these middens are leading to the trees growing in their midst to be fuller, taller, and healthier than their other forest neighbours.