Back in the 1800's (yes, another history lesson... suck it up Marine!) the prevailing philosophy amongst early conservationists was that predators were harmful to nature. It seemed to make sense, predators killed and ate game species, they killed livestock, and they just plain looked scary. It's as if they thought that nature couldn't handle herself she needed us humans to paternalistically step in and keep the big bad wolves from wiping out the poor little game species.
So, if predators are harmful to nature, then it only makes sense that if we want to preserve nature we should eradicate as many predators as possible. Right? Sure! What could go wrong? For decades it was the official policy of the US government to exterminate as many predators as possible. Bounties were placed on wolves and other predator species and they were culled en masse. By the 1930's wolves were essentially extinct in the lower 48. Other apex predators like mountain lions and brown bears fared only marginally better. Then, like in so many other environmental issues, one particular case became the canary in the coal mine and clued conservationists into the fact that there was something fundamentally wrong with their model of how nature works. For the issue of predator culling that proverbial canary was the Kaibab Plateau.
In 1906 Teddy Roosevelt set up the Grand Canyon National Game Preserve on the plateau with the intention of bolstering the native deer population. In keeping with the conservation philosophy of the time, all of the natural predators living on the plateau were exterminated and hunting on the plateau was banned under the same reasoning. The ecologists of the time predicted that this would lead to an unprecedented, thriving deer population. For the first few years, the results appeared to confirm their predictions... until reality set in.
As the Deer population density soared, diseases were more easily passed between individuals and were soon running rampant. However, the more drastic problem happened when the deer population began to bump up against that proverbial glass ceiling imposed by the ecosystem's carrying capacity. The overinflated deer population soon decimated almost all the vegetation on the plateau. Without the plants' roots to hold the soil in place, erosion quickly swept away all of the fertile soil. By the 1920's thousands of deer were starving to death and what remained of the population was addled with disease. To make matters worse, the erosion had left the plateau barren, curtailing its productivity for decades to come.
The prevailing philosophy of the time was that the very presence of predators was harmful to the ecosystem in general and game species in particular. The Federal Government carried this philosophy to its logical end and implemented it as fully as is possible on the Kaibab Plateau. To call the results of that effort a total and unmitigated failure would be a forgiving description.
You'd think that such a philosophy would be entirely abandoned nearly a century after having been so thoroughly disproven.