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extinction — English
The complete disappearance of a species from the global ecosystem. For millions of years natural forces of environmental change had resulted in the extinction of innumerable species all over the Earth (on land as well as in the oceans), but it had also led to the origin of many new species as organisms adapted to their changed environment. Extinction happens when a species (either animal or plant) cannot evolve (or change) fast enough to adapt to a changing environment. This is what happened with the dinosaurs some 70 million years ago when the global climate changed and the animals and plant species of the time could not survive the drier, warmer conditions. Most of the fossil animals found in the caves of the Cradle of Humankind World Heritage sitehad been extinct for thousands or even millions of years. The global environment is always changing, and that will always lead to the natural extinction of certain animals and plants. Global natural environmental change usually happens slowly, and many species can change and adapt to a changed environment, provided the change takes place over thousands or millions of years. However, for the past few hundred years, human activities have been the greatest force for accelerated extinction. Some species have been hunted to extinction, the famous dado and the Cape quagga are examples of animals that went extinct over the last few hundred years. All species of rhinoceros in Africa and Asia seem doomed to extinction. The most active and dangerous human-induced (anthropogenic) cause of extinction is habitat loss, habitat degradation (see “environmental degradation”) and habitat fragmentation that humans bring about. Owing to habitat loss the blue swallow of Kaapsche Hoop in South Africa is very nearly extinct. With less than 30 breeding pairs the genetic pool is so small that it would probably not be able to escape extinction. Habitat loss is also responsible for the fact that two species of South Africa’s cranes are teetering on the brink of extinction. South Africa’s national bird, the blue crane, was very nearly extinct when a number of nongovernmental, environmental organisations stepped in with a successful protection and breeding project. The species is still threatened, but there is hope that it might still be rescued.
