In the known history of the world, there were five events known as the "Five Great Extinctions". These events were (as the name obviously implies) massive extinctions on a global scale, the worst of these actually killing 90% of the species existing at the time.
One that is actually well known is the one that caused the extinction of the dinosaurs, which was actually the "best", killing a smaller number of species when compared to any other. It's been hard to determine the causes, but they're generally attributed to climate changes.
Currently, however, we are facing a mass extinction that may surpass the worst the world has seen so far, and like many other things, it's because of us.
And it's not recent either, as some people like to actually divide this "Sixth Extinction" into two parts: the first part being between our appearance and the the creation of agriculture and the second part between that and now.
Our influence was actually felt whenever we reached new land, any land that wasn't used to us. As we hunted there for food, which were normally medium or large sized animals, certain species either became rarer or disappeared entirely, normally the largest being the first to go due to both having to compete with us and being hunted themselves.
This is easy to see when you consider that at this time, the only place we existed in where this did not happened was in Africa, in other words, the place where Homo Sapiens first appeared before spreading and what we could call our original ecosystem, one that was used to us at the time, unlike the rest of the world.
We were even partially responsible for the extinction of our cousins, the Neanderthal, in the region now know as Europe (however, their biggest problem was the change in climate)
When agriculture was invented it only gave us more reasons to mess with the various ecosystems, since we needed the land for the crops, and we haven't taken a look back since, rising the number of problems caused in an extraordinary way, now being the cause for global warming itself.
Simply put, we need to act soon before nothing at all can be done, as current numbers are alarming, with an estimation of 3 species going extinct each hour. And it won't be easy.
Information from:
http://en.wikipedia.org/wiki/Mass_extinction
http://www.actionbioscience.org/newfrontiers/eldredge2.html
Images taken from:
http://en.wikipedia.org/wiki/File:Tyrannosaurus_BW.jpg
http://en.wikipedia.org/wiki/File:Neanderthaler_Fund.png
I never seen that point of view before and you have done a great post but i must disagree with we be the destroyers that is not completly true, that was our way to survive and it still is. yes is true that we kill animals and destroy natural habitats but the nature created us like this, we need to eat, we need to drink, we need space, the only bad thing is that before we only hunted and produced what we needed now we do that to the extreme.
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