You see the impact of humans on Earth's environment every day. We are trashing the place: There is plastic along our highways, the smell of a landfill, the carbonic acid (formed when carbon dioxide is dissolved in water) bleaching of coral reefs, the desertification of enormous areas of China and Africa (readily seen in satellite images), and a huge patch of plastic garbage in the Pacific Ocean. All of these are direct evidence of our effect on our world. We are killing off species at the rate of about one per day. It is estimated that humans are driving species to extinction at least a thousand times faster than the otherwise natural rate. Many people naively (and some, perhaps, deceptively) argue that loss of species is not that important. After all, we can see in the fossil record that about 99 percent of all the different kinds of living things that have ever lived here are gone forever, and we're doing just fine today. What's the big deal if we, as part of the ecosystem, kill off a great many more species of living things? We'll just kill what we don't need or notice. The problem with that idea is that although we can, in a sense, know what will become or what became of an individual species, we cannot be sure of what will happen to that species' native ecosystem. We cannot predict the behavior of the whole, complex, connected system. We cannot know what will go wrong or right. However, we can be absolutely certain that by reducing or destroying biodiversity, our world will be less able to adapt. Our farms will be less productive, our water less clean, and our landscape more barren. We will have fewer genetic resources to draw on for medicines, for industrial processes, for future crops. Biodiversity is a result of the process of evolution, and it is also a safety net that helps keep that process going. In order to pass our own genes into the future and enable our offspring to live long and prosper, we must reverse the current trend and preserve as much biodiversity as possible. If we don't, we will sooner or later join the fossil record of extinction.