You are probably all aware of the mongoose problem in Hawaii. If not, quite a few years ago a planter there had the idea that if they imported some mongeese they would eat the rats that were a problem. As it turns out this was not a very good idea. The mongeese were diurnal whereas the rats were nocturnal. So nothing happened to the rats while the mongeese turned their attention to birds eggs and such and became and remain a serious problem.
In Australia a man who had emigrated from England was a bit of a sportsman. He enjoyed hunting rabbits. There were no rabbits in Australia so he had a friend send him twenty or so, so he could hunt them there. Another disaster. The rabbits had no enemies in Australia and in that warm climate could breed all year round. So the rabbit population soared until there were millions of them and they devastated much of the environment. Hunting them didn't even make a dent in the growing population and to this day they still poison them and build huge fences to try to control them.
Another Australian had the great idea to import toads. There were no toads in Australia, just some frogs. The toads were meant to eat the cane beetles that infested the cane fields. Turned out the toads couldn't jump high enough to reach the beetles so...another disaster. Toads now overrun Australia. There are millions upon millions. They have helped destroy the ecosystem and created still another disaster.
Perhaps you haven't heard of the great beaver problem in Argentina. It seems some people there thought importing beavers was a good idea as they could sell the pelts and make money. So some 50 beavers were imported and set to work. As there were no natural enemies of the beavers, and as the country was ideal beaver country with lots of the right kinds of trees and many streams and rivers, the beavers thrived and now constitute a terrible problem.
There are many other such cases I am sure. It is often the case that even good intentions go astray. For example, many thought that eliminating Sadam Husein was a good idea. Perhaps it was, but the Iraqis now wish he was back as their conditions now are worse than they were to begin with. And you can see what trying to introduce democracy at the point of a gun does to a country.
Why is it that human beings insist on meddling everywhere. We seem to be not content with anything anywhere. We dam the rivers and destroy the salmon runs. We overfish the oceans so that many species of fish are virtually extinct. We overlogged the forests and damaged rivers and streams. We have radically changed the environment so that many species no longer exist. We shot all the Passenger Pigeons and tried as hard as we could to shoot all the buffalo. We killed whales like there was no tomorrow. And on and on and on. We seem to be inveterate meddlers and we meddle in things we more often than not when we do not understand the consequences, look at the pharmaceutical industry, for example, or genetically engineered food, or the implications of nuclear power, strip mining, etc., etc. Shoot first and ask questions later seems to be our motto when it comes to most everything. You might think that if something is suspected of being potentially harmful we would refrain from using it, but we don't. Our plan is to use it first and see if it has harmful consequences later. Good planning, huh?
People were not always so:
"We were contented to let things remain as the Great Spirit Chief made them. They were not; and would change the mountains and the rivers if they did not suit them."
It appears that many of the changes we have wrought do not suit us and in some cases it is too late even to do anything about it. Our existing capitalistic system is not very conducive to doing the right thing. Can we do better from now on. We had better hope so.