In the past, species would go extinct in the natural world at a rate of around one every 190 years, but today, with the growth in the human population and the overexploitation of plant and animal resources, a living species disappears from the face of the earth every 20 minutes.
由於人口擴張，與對自然環境缺乏適度的開發，過去自然界約每一百九十年才會有一種生物絕跡，如今每二十分鐘，就有一種生物從地球上消失。