Extinction, called by E. O. Wilson the death of birth, is the permanent loss of a species from Earth because of loss of its mating capacity, climate adaptation and habitat, food supply, or other cause.
A species at risk of extinction is sometimes generically called an endangered species but this is a more technical term used by biologists. Saying "at risk" can imply for instance a more local danger that will extinct a species only in one place - whereas it might thrive elsewhere.
Today the overwhelming cause of extinctions is human beings and the changes made to the landscape for agriculture and forestry. While there are some oceanic extinctions due to fishery, most fresh water extinctions are due to erosion and dams.
Biologists call today the Sixth Great Dieoff as it is the sixth time in nkown geological history that a vast number of species died or are expected to. Climate change alone is expected to reduce Earth's biodiversity very drastically, as most of that diversity is in sensitive river and coast regions.
Ape extinction is a particular moral problem for humans because these are our own near relatives. If we let them die off we clearly lack empathy and even the ability to care for those more rather than less like us. Accordingly many people believe that an ape extinction signals a more general human dieoff, as people in general abandon the idea of humans ever becoming caring about other species, and an "every man for himself" attitude begins to develop.