Extinction
...e forests that existed in 1950." (Raven 38) Human beings, one of the ten million species on earth, have done all of this. We are losing plant and animal species at one thousand to ten thousand times the natural rate. Judging from the fossil record, we are only supposed to lose four species per year, but the most recent estimated total is around fifty thousand. This number will probably increase as we move forward to the new millennium. If we keep losing species at this rate, we will lose two-thirds of our entire species on Earth which is equivalent to what happened at the end of the Cretaceous Period. It took the Earth five million years to rebound from that disaster. These five million years are time humanity does not have. The reason we are now kept alive is because of biodiversity. Biodiversity is the reason that we have cures for many diseases, regulated climates, and atmospheric quality. Biodiversity absorbs pollution and generates and maintains soil. With the way that we are going now, biodiversity will not be saved. We will keep on using and using as our population and consumption needs arise. The only was to stop this decline in our environment is to cap or control the human population. We can do this by putting limits on how many children a woman can have, or we can address many bigger social problems such as poverty and injustice done by people throughout the world. We need to somehow control our over consumption of natural resources in our already industrialized nations and stop poverty and disease in our world's developing countries. These problems have to be addressed before any possible solutions for extinction can be put into action. One of these possible solutions would be the setting up of a worldwide system of protected areas. There would have to be protection outside of these areas. Plants would be one likely target for this help. Seed banks could be created and botanical gardens set up all around the world. We are now living in what it must have been like at the end of the Cretaceous Period. "We have the opportunity to sample a full range of biodiversity with which we co-exist, opportunities that may never occur again."(Raven 38) The principle reason why things become extinct is because their habitat is destroyed.(Case 84) The reason for extinction thought by some scientists is the introduction of foreign organisms, whether it may be tiny bacteria or humans. The work of Ted Case at the University of California may prove this theory wrong. His works are based on the release of birds on seventy isolated islands one of which was Australia. The number of successfully introduced birds, 473, was similar to the number of birds that became extinct, 367. Now it might seem as if the species that became extinct did so because of direct competition with the newly introduced birds. It turned out that the birds who were successful had completely different habitats than the species who became extinct. The successful birds could survive in man made areas like grasslands and parks while the extinct birds lived in natural habitats like swamps and forests. These swamps and forests were pumped dry and cut down to meet human consumption needs. This study gives proof to Case's Theory. "The loss of natural habitat equals the amount of unnatural habitat created." (Case 84) Scientists now think that mass extinctions are about to happen because continents are now being formed into habitatal islands. Some think that we may even be headed to a catastrophic crash like the one at the end of the Cretaceous when seventy-five percent of all species vanished. This disappearing act is called biodiversity crisis, but no one really knows if it is happening right now. There is no way to know how many species there are on Earth, so consequently there is no way to tell how many are becoming extinct. We could be gaining tens of thousands of species a year for all we know. "Scientists each year come out with numbers on how many species we have lost, but without facts to back it up it is just handwaving." (Schmidt 26-28) "Data from the World Conservation Union estimates that in ten years thirty-four percent of the fish, twenty-five percent of the amphibians and mammals, twenty percent of reptiles, and eleven percent of birds will be threatened with extinction." (Schmidt 26-28) These rates seem high but they do not prove mass extinction. If these species do not become extinct for another thousand years then the rate will be normal. Scientists cannot prove that species become extinct either because they cannot cover every part of the globe. Because of the work of David Tillman at the University of Minnesota, scientists only now have found out that a world without many species is a bad thing. In 1982 Tillman decided to study 207 plots of land in the Minnesota prairie. These plots contained one to twenty-six different species of grass and broad leaf plants. In 1987 to 1988 Minnesota had a drought. During this drought Tillman and his colleagues discovered that the more complex societies of plants were more able to obtain nitrogen from the soil during that time. "Tillman's Theory is that the complex societies do not allow diseases and weeds to zero in on their favorite targets." (Schmidt 26-28) One hundred years ago passenger pigeons covered North America. There flocks were ...