Extinction is the termination of an organims or of a group of organisms , normally a species . The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Causes : -As long as species have been evolving, species have been going extinct. It is estimated that over 99.9% o f all species that ever lived are extinct. The average lifespan of a species is 1–10 million years -S pecies that cannot survive and reproduce in its environment and cannot move to a new environment where it can do so, dies out and becomes extinct. - The question of whether more extinctions in the fossil record have been caused by evolution or by catastrophe is a subject of discussion Habitat degradation: is currently the main anthropogenic cause of species extinctions. The main cause of habitat degradation worldwide is agriculture, with