[Bacteria are the] dark matter of the biological world [with 4 million mostly unknown species in a ton of soil].

Biological diversity is the key to the maintenance of the world as we know it. Life in a local site struck down by a passing storm springs back quickly: opportunistic species rush in to fill the spaces. They entrain the succession that circles back to something resembling the original state of the environment.

Biology is a science of three dimensions. The first is the study of each species across all levels of biological organization, molecule to cell to organism to population to ecosystem. The second dimension is the diversity of all species in the biosphere. The third dimension is the history of each species in turn, comprising both its genetic evolution and the environmental change that drove the evolution. Biology, by growing in all three dimensions, is progressing toward unification and will continue to do so.

I believe it’s worth emphasizing that a scientist and a graduate student in college, and a kid in grammar school all can start with understanding something new by exploring even the simplest and most common forms of life you find right in the heart of the city. Along a fringe of a street, along the edges and into a city park, is a multitude of species, of associations, of phenomena going on that scientists themselves have not fully come to understand.

I think it [my ideal birthday present] would be a commitment in the policy of the United States and internationally to go for the exploration and identification and protection of every species on Earth, with the same vigor that is building toward stabilizing earth’s climate, because the two are intimately linked.

In a purely technical sense, each species of higher organism—beetle, moss, and so forth, is richer in information than a Caravaggio painting, Mozart symphony, or any other great work of art. Consider the typical case of the house mouse, Mus musculus. Each of its cells contains four strings of DNA, each of which comprises about a billion nucleotide pairs organized into a hundred thousand structural nucleotide pairs, organized into a hundred thousand structural genes. … The full information therein, if translated into ordinary-sized printed letters, would just about fill all 15 editions of the Encyclopaedia Britannica published since 1768.

In the process of natural selection, then, any device that can insert a higher proportion of certain genes into subsequent generations will come to characterize the species.

It may be argued that to know one kind of beetle is to know them all. But a species is not like a molecule in a cloud of molecules—it is a unique population.

It may be argued that to know one kind of beetle is to know them all. But a species is not like a molecule in a cloud of molecules—it is a unique population.

More than 90 percent of the forests of western Ecuador have been destroyed during the past four decades.The loss is estimated to have extinguished or doomed over half of the species of the area’s plants and animals. Many other biologically diverse areas of the world are under similar assault.

No one knows the diversity in the world, not even to the nearest order of magnitude. … We don’t know for sure how many species there are, where they can be found or how fast they’re disappearing. It’s like having astronomy without knowing where the stars are.

No species … possesses a purpose beyond the imperatives created by genetic history … The human mind is a device for survival and reproduction, and reason is just one of its various techniques.

Now when you cut a forest, an ancient forest in particular, you are not just removing a lot of big trees and a few birds fluttering around in the canopy. You are drastically imperiling a vast array of species within a few square miles of you. The number of these species may go to tens of thousands. … Many of them are still unknown to science, and science has not yet discovered the key role undoubtedly played in the maintenance of that ecosystem, as in the case of fungi, microorganisms, and many of the insects.

One in ten plant species contains anticancer substances of variable potency, but relatively few have been bioassayed.

The elements of human nature are the learning rules, emotional reinforcers, and hormonal feedback loops that guide the development of social behaviour into certain channels as opposed to others. Human nature is not just the array of outcomes attained in existing societies. It is also the potential array that might be achieved through conscious design by future societies. By looking over the realized social systems of hundreds of animal species and deriving the principles by which these systems have evolved, we can be certain that all human choices represent only a tiny subset of those theoretically possible. Human nature is, moreover, a hodgepodge of special genetic adaptations to an environment largely vanished, the world of the Ice­Age hunter-gatherer.

The most wonderful mystery of life may well be the means by which it created so much diversity from so little physical matter. The biosphere, all organisms combined, makes up only about one part in ten billion of the earth’s mass. … Yet life has divided into millions of species, the fundamental units, each playing a unique role in relation to the whole.

The origin of species is therefore simply the evolution of some difference—any difference at all—that prevents the production of fertile hybrids between populations under natural conditions.

The totality of life, known as the biosphere to scientists and creation to theologians, is a membrane of organisms wrapped around Earth so thin it cannot be seen edgewise from a space shuttle, yet so internally complex that most species composing it remain undiscovered. The membrane is seamless. From Everest's peak to the floor of the Mariana Trench, creatures of one kind or another inhabit virtually every square inch of the planetary surface.

The worst thing that will probably happen—in fact is already well underway—is not energy depletion, economic collapse, conventional war, or the expansion of totalitarian governments. As terrible as these catastrophes would be for us, they can be repaired in a few generations. The one process now going on that will take millions of years to correct is loss of genetic and species diversity by the destruction of natural habitats. This is the folly our descendants are least likely to forgive us.

There are three levels of biodiversity that we’re trying to save: ecosystems, then the species in the ecosystems, and then the genes that prescribe traits of the species that make up the ecosystem. And we should decide upon areas to be saved not by the general appearance or what are the main ecosystems in them. We don’t know enough about ecosystems. We should be choosing them according to the number of species that are in each. And particularly the number of endangered species of some kind.

Thus, remarkably, we do not know the true number of species on earth even to the nearest order of magnitude. My own guess, based on the described fauna and flora and many discussions with entomologists and other specialists, is that the absolute number falls somewhere between five and thirty million.

True spite is a commonplace in human societies, undoubtedly because human beings are keenly aware of their own blood lines and have the intelligence to plot intrigue. Human beings are unique in the degree of their capacity to lie to other members of their own species.

When you leave intact as many species as possible, in a major habitat, whether it’s a pond or a bay or a forest somewhere, the better it functions. And the better it functions, the better it serves.