When fourteen Canadian wolves were released into Yellowstone in 1995, they were credited with bringing back trees, beavers and even changing the course of rivers, but a 20-year experiment suggests the most famous conservation story on the internet may be far more complicated

It presented the trophic cascade — the ecological term for a top-down effect from a predator through multiple lower trophic levels — as a demonstrated fact. What the science actually showsThe primary scientific case for the Yellowstone trophic cascade came from a research team led by William Ripple and Robert Beschta at Oregon State University. A 2025 paper by Painter and others reaffirmed the case for a real, if weaker, trophic cascade effect, and criticised the Hobbs/Cooper analysis on methodological grounds. Why the disconnect mattersThe Yellowstone wolves story is a specific case study in how popular science can outrun the evidence base it is drawn from. By 2014, when the video was released, the trophic cascade thesis had already been peer-reviewed and challenged.