There are currently 1.4 million described species on earth, but estimates of as many as 5 to 50 million total species have been projected to exist (Becher, 1998, 60). Tropical entomologist Terry Erwin’s research supports that there may be as many as 30 million insect species alone in the tropical rainforests (Shiva et al, 1991, 14). One of the true challenges to biodiversity is that there are so many species that we may be obliterating that we are not even aware exist yet. We are destroying species faster than we can identify them.
Extinction and evolution are a normal part of the life cycle on Earth. Of all the species that ever have lived on the earth only between one and six percent exist today (Shiva et al, 1991, 15). Many mass extinctions have previously occurred killing of as much as 90% of life on earth in one fell swoop. In 1995 there were 26,106 species of mammals, birds, reptiles, amphibians, fishes invertebrates and plant that were considered endangered, vulnerable rare or indeterminate, (Watson, 1995, 26), that figure is certainly higher today. Conservation biologists warn that 25 percent of all species could become extinct during the next twenty to thirty years (Shiva et al, 1991, 15).
The difference between the previous extinctions and the ones currently taking place are the time line and the cause. Where as in the past as one species fell out of existence another had sufficient space on the geological timeline to replace and therefore replenish the biological diversity. Fossils show that the birth and death of a species occur on a million year timescale-called a background rate ( Pimm et al, 2005). Currently the extinction rate is 40,000 times higher than this “background” rate (Shiva et al, 1991,16). Though humans evolved along side the millions of others we are now the force that rules over the existence or demise of our fellow inhabitants. We are replacing the natural delicately balanced ecosystem with our own habitat....
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