Extinction of megafauna is almost a global phenomenon. Most of the world's continents and islands have lost the larger members of their fauna at some time over the last 50,000 years. Africa is the only continent which has not suffered significant extinctions.
In answering the question 'Why is this so?', I propose that people caused the extinction of megafauna' in a blitzkrieg-like fashion. This theory is based on the world-wide pattern of extinctions for the following reasons:
Firstly, the most important points about the extinction of megafauna are associated with timing. Megafauna became extinct up to 50,000 years ago in Australia and New Guinea, around 10,900 years ago in North (and presumably South) America, about 1500 years ago in Madagascar, and between 900 and 600 years ago in New Zealand. This pattern closely follows the current chronology of human expansion around the world.
Secondly, megafauna are the biggest and slowest animals in the environment. These kinds of animals are very vulnerable to hunting, but not to climate change. As people did not arrive in Africa, but evolved there, the evolution of our human ancestors from scavengers into skilled hunters happened slowly, allowing the ecosystem and its abundant megafauna time to adjust. However, that did not happen elsewhere. The extinction of megafauna was most extreme in places where humans arrived as already skilled hunters.
Other evidence to support a human-caused extinction includes the relatively recent extinction of megafauna, such as those in South Africa after 1820, when rifles were introduced. With this kind of weaponry, humans can clearly exterminate large mammals and other defenceless species.
Australasia's megafauna were once very diverse. Some species lived in the eternally wet rainforests of Papua New Guinea, while others lived in the driest deserts. The other theory of megafauna extinction that is based on climate change must argue that extinction could have happened at almost any time in the last 50,000 years, whether the climate has been warm and wet or cold and dry, or any combination in between. Under this scenario, it is my opinion that the influence of climate on megafauna extinction was so weak that it must have been negligible.
Tim Flannery
Mammals
Australian Museum
Copyright © Australian Museum, 2003
This page: http://www.amonline.net.au/factsheets/megafauna_extinction.htm
