Our planet's untouched natural environments are shrinking, due to pressure from human populations. As these areas decline, the creatures adapted to live in them face a decline in numbers, and sometimes even extinction altogether. Many biologists believe that if we don't act quickly, half the world's species will be gone in 100 years. A report called the Living Planet Index reveals that from 1970 to 2000, populations of terrestrial and marine species dropped by 30 percent, while freshwater populations went down by a massive fifty percent. |