Life is good at dying, and there have been multiple periods in the timeline of Earth’s history where life was nearly obliterated for good. Extinction is a natural phenomenon in which all members of a species completely die off, and mass extinction events are some of the most dramatic happenings on Earth. Abrupt shifts in the environment can turn entire ecosystems on their heads, and whole families of animals can disappear in a geologic milli-second (which is why people should kind of, sort of care about critically endangered species).
Some threats came from outer space, like the violent meteor extinction of dinosaurs. Others, like the Holocene extinction, are caused by forces a little closer to home. Volcanoes, meteors, invasive species, climate change, and a host of other things can all trigger an extinction event, and there’s nothing to stop another one from happening. If we want to avoid a repeat of any of these calamitous events in our lifetimes, it may be wise to look at the history of mass extinctions and the devastation they bring with them.