In many environments, take away the ants and there would be partial collapses in many of the land ecosystems.

Real biologists who actually do the research will tell you that they almost never find a phenomenon, no matter how odd or irrelevant it looks when they first see it, that doesn't prove to serve a function. The outcome itself may be due to small accidents of evolution.

Well, let me tell you, ants are the dominant insects. They make up as much as a quarter of the biomass of all insects in the world. They are the principal predators. They're the cemetery workers.

E. O. Wilson Quotes