Why do species become endangered or extinct?
People who dont care what happens to plants and animals often like to point out that extinction is normal. While this is true, something else is also true that these people rarely mention: extinction is also infrequent unless some disaster causes a mass extinction event. In all the history of life on Earth, there have been only five such events, caused by major cataclysms such as worldwide volcanic activity and/or asteroids hitting the Earth. Unfortunately, a sixth mass extinction is now under way and this one is caused entirely by human beings. There is uncertainty over how fast the wipe-out is moving, but biologists agree that the current extinction rate is much higher than the normal background rate. That normal rate may be 1 species per year or 1 per century, depending on what expert you hear. The current rate is unknown, partly because we dont even know how many species there are. But estimates run as high as 50-150 species per day. In short, humans are killing anywhere from 100 t
