Why does organisms disappear overtime?

Extinction is a natural process that may be caused by natural selection, shortage of food or natural calamities. Hunting, deforestation, pollution, the conversion of uncultivated areas into pastures, the illicit trade of wild animals as well as climatic changes have made life more difficult for many animals.

The disappearance of species. An animal species is seriously threatened with extinction when its population is broken up. Extinction is a natural process that may be caused by natural selection, shortage of food or natural calamities.