If you’ve driven on a highway in a wooded area in the fall, chances are, you’ve seen the results of our almost-complete removal of apex predators from American ecosystems. By removing wolves and bears and cougars, we’ve basically insured that highways through all of Pennsylvania and Ohio are carpeted in deer roadkill. It’s gross.

We’ve long known that removing apex predators has disastrous consequences on the ecosystem, but in this video by Sustainable Man, narrated by environmental activist George Monbiot, we finally see how huge of an effect reintroducing wolves to an ecosystem (like Yellowstone National Park in Wyoming) can have: wolves can change the very course of the rivers.

Rivers aside, I’m all for reintroducing wolves to Ohio and the East Coast, if for nothing else, to get the damn deer carcasses out of the left-hand lane. Feature photo: Steve Jurvetson