Home >> Science & Nature >> Animals & Science

Four Reasons That Animals Go Extinct

In the history of the Earth there have been 5 great extinction events. According to Ellen Thomas of Wesleyan University, a mass extinction is defined as a rapid event which causes a significant part of the Earth's life forms, of different phyla, in different habitats, spread across the world to become extinct. In the context of the Earth's history, a "rapid event" could happen over several hundred years. We now appear to be headed toward a sixth great extinction event, and while this one may be man-made, it has much in common with the others.

Climate Change
- Climate change appears to have been a factor in four of the five great extinction events. The fifth and most recent event occurred about 65 million years ago and is believed to have been caused by a giant meteorite, which caused a rapid change in ecosystems. This had essentially the same effect as climate change. The Earth is undergoing climate change again, and plants and animals that cannot adapt to sudden changes in their environment may become extinct.
Loss of Habitat
- The loss of habitat is a frequent cause of extinction. During a period of climate change there is widespread loss of habitat. As the climate warms or cools, temperature, moisture levels, plant life and other factors that animals have come to rely on change. Some animals cannot adapt to the change and die out. In the modern period, the loss of habitat is more extreme. Human encroachment on animals' natural habitats for farming, forestry, or development threatened many species even before the current warming period began.
Keystone Species
- The extinction of one species of plants or animals can lead to the extinction of others. If, for example, an animal that is the primary food source of another animal becomes extinct, the carnivore is at risk of extinction as well unless it can find an alternative food source. Some species are called keystone species. These species provide the base diet for multiple other animals or otherwise play an important role in the ecosystem. The loss of a keystone species, such as plankton in the aquatic food chain, or bees that pollinate plants, can lead to the extinction of many species.
Modern Problems
- While loss of habitat, the loss of keystone species and climate change have historically led to extinctions, human civilization has introduced new causes. Over-hunting brought the African elephant, rhinoceros and American buffalo, among others, to the brink of extinction before they were protected. The pollution of waterways has lead to the extinction of a number of amphibian species and put hundreds of others at risk. Environmental pollution has been controlled, to an extent, in developed nations, but in many poorer developing countries there are few pollution controls in place.

Animals & Science