Natural

The mechanism by which life began on Earth is unknown, although many hypotheses have been formulated. Since emerging, life has evolved into a variety of forms, which have been classified into a hierarchy of taxa. Life can survive and thrive in a wide range of conditions. ... Nonetheless, more than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to be extinct. Estimates on the number of Earth's current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. — en.wikipedia.org