It's sort of the butterfly effect, only tighter scale and and more explainable: introducing wolves to Yellowstone National Park caused changes in the rivers in the park. How? Watch and see.
Very cool.
Originally shared by +Yonatan Zunger:
And now I want to share with you one of the most interesting short videos I've seen in a while. It's about the idea of trophic cascades: how a small change to an ecosystem can lead to tremendous consequences. In this case, the change was the reintroduction of wolves to Yellowstone in the 1990's, after a 70-year absence.
The direct effects of the wolves were small: the wolves eat a few deer, but apart from that mostly keep to themselves. But the indirect effects were huge.
It started because the deer, who had been running roughshod over the entire park, quickly figured out that places like valleys were not good places to be a deer when there are wolves about. This led to trees being able to grow in those areas for the first time in decades.
The effects of that are complex and profound, and I encourage you to watch the video, because I can't possibly summarize it better than it does. Everything from the animals to the plants to the very physical geography of the rivers was changed.
The key lesson of this is that ecosystems are connected. You can't make a single change to one and expect it not to have consequences, including very far-reaching ones of a sort you couldn't ever have predicted. This is a general property of all large, strongly-interacting systems, including societies, and it's worth keeping in mind whenever things change.