If enough species are extinguished, will the ecosystems collapse, and will the extinction of most other species follow soon afterward? The only answer anyone can give is: possibly. By the time we find out, however, it might be too late. One planet, one experiment.

Most people believe they know how they themselves think, how others think too, and even how institutions evolve. But they are wrong. Their understanding is based on folk psychology, the grasp of human nature by common sense ¾ defined (by Einstein) as everything learned to the age of 18 ¾ shot through with misconceptions, and only slightly advanced over ideas employed by the Greek philosophers

The human juggernaut is permanently eroding Earth's ancient biosphere.

We don't even know what species are out there, for the most part, particularly when you get down to the microbes and very small invertebrates. They make up the mass of the organisms around us, including the soil we depend on, the soil of cornfields as well as hardwood forests. We haven't taken ecology to the point where we can even make a crude prediction of what's going to happen when we've reduced the living world down to a certain level.

Nature holds the key to our aesthetic, intellectual, cognitive and even spiritual satisfaction.

And pigs may fly. And we may be able to terraform and send surface populations to Mars. And Jesus may come next week anyway, so it doesn't matter one way or the other. All these crazy things run through people's minds.

Most people are surprised when they hear my somber figures: we know of 2 million species of plants, animals and microorganisms, and we can give them each a scientific name and a diagnostic description. We know, perhaps generously, more than just a little bit of the anatomy in no more than 10 percent. We have done thorough studies in fewer than one-tenth of 1 percent. And the total number of species on Earth is unknown to the nearest order of magnitude.