A lot of people ask, 'Do you think humans are parasites?' It's an interesting idea and one worth thinking about. People casually refer to humanity as a virus spreading across the earth. In fact, we do look like some strange kind of bio-film spreading across the landscape. A good metaphor? If the biosphere is our host, we do use it up for our own benefit. We do manipulate it. We alter the flows and fluxes of elements like carbon and nitrogen to benefit ourselves—often at the expense of the biosphere as a whole. If you look at how coral reefs or tropical forests are faring these days, you'll notice that our host is not doing that well right now. Parasites are very sophisticated; parasites are highly evolved; parasites are very successful, as reflected in their diversity. Humans are not very good parasites. Successful parasites do a very good job of balancing—using up their hosts and keeping them alive. It's all a question of tuning the adaptation to your particular host. In our case, we have only one host, so we have to be particularly careful.

After having produced aquatic animals of all ranks and having caused extensive variations in them by the different environments provided by the waters, nature led them little by little to the habit of living in the air, first by the water's edge and afterwards on all the dry parts of the globe. These animals have in course of time been profoundly altered by such novel conditions; which so greatly influenced their habits and organs that the regular gradation which they should have exhibited in complexity of organisation is often scarcely recognisable.

As crude a weapon as a cave man's club, the chemical barrage has been hurled against the fabric of life.

Civilization is in no immediate danger of running out of energy or even just out of oil. But we are running out of environment—that is, out of the capacity of the environment to absorb energy's impacts without risk of intolerable disruption—and our heavy dependence on oil in particular entails not only environmental but also economic and political liabilities.

Even in the vast and mysterious reaches of the sea we are brought back to the fundamental truth that nothing lives to itself.

Faced with the widespread destruction of the environment, people everywhere are coming to understand that we cannot continue to use the goods of the earth as we have in the past … [A] new ecological awareness is beginning to emerge which rather than being downplayed, ought to be encouraged to develop into concrete programs and initiatives. (8 Dec 1989)

For the source of any characteristic so widespread and uniform as this adaptation to environment we must go back to the very beginning of the human race.

From first to last the civilization of America has been bound up with its physical environment.

History in its broadest aspect is a record of man's migrations from one environment to another.

I shall collect plants and fossils, and with the best of instruments make astronomic observations. Yet this is not the main purpose of my journey. I shall endeavor to find out how nature's forces act upon one another, and in what manner the geographic environment exerts its influence on animals and plants. In short, I must find out about the harmony in nature.

If all mankind were to disappear, the world would regenerate back to the rich state of equilibrium that existed ten thousand years ago. If insect were to vanish, the environment would collapse into chaos.

In fact, the history of North America has been perhaps more profoundly influenced by man's inheritance from his past homes than by the physical features of his present home.

It hurts the spirit, somehow, to read the word environments, when the plural means that there are so many alternatives there to be sorted through, as in a market, and voted on.

It is not the organs—that is, the character and form of the animal's bodily parts—that have given rise to its habits and particular structures. It is the habits and manner of life and the conditions in which its ancestors lived that have in the course of time fashioned its bodily form, its organs and qualities.

It's a numbers game—in a dense urban area there are so many of us that even unintentional pollution would cause all the crap we see in the water.

Later scientific theories are better than earlier ones for solving puzzles in the often quite different environments to which they are applied. That is not a relativist's position, and it displays the sense in which I am a convinced believer in scientific progress.

Man cannot have an effect on nature, cannot adopt any of her forces, if he does not know the natural laws in terms of measurement and numerical relations. Here also lies the strength of the national intelligence, which increases and decreases according to such knowledge. Knowledge and comprehension are the joy and justification of humanity; they are parts of the national wealth, often a replacement for the materials that nature has too sparcely dispensed. Those very people who are behind us in general industrial activity, in application and technical chemistry, in careful selection and processing of natural materials, such that regard for such enterprise does not permeate all classes, will inevitably decline in prosperity; all the more so were neighbouring states, in which science and the industrial arts have an active interrelationship, progress with youthful vigour.

No part of the world can be truly understood without a knowledge of its garment of vegetation, for this determines not only the nature of the animal inhabitants but also the occupations of the majority of human beings.

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 tragic example of the loss of forests and then water is found in Ethiopia. The amount of its forested land has decreased from 40 to 1 percent in the last four decades. Concurrently, the amount of rainfall has declined to the point where the country is rapidly becoming a wasteland.

Over increasingly large areas of the United States, spring now comes unheralded by the return of the birds, and the early mornings are strangely silent where once they were filled with the beauty of bird song.

Second Law
All the acquisitions or losses wrought by nature on individuals, through the influence of the environment in which their race has long been placed, and hence through the influence of the predominant use or permanent disuse of any organ; all these are preserved by reproduction to the new individuals which arise, provided that the acquired modifications are common to both sexes, or at least to the individuals which produce the young.

The 'control of nature' is a phrase conceived in arrogance, born of the Neanderthal age of biology and the convenience of man.

The choice to 'do nothing' in response to the mounting evidence is actually a choice to continue and even accelerate the reckless environmental destruction that is creating the catastrophe at hand.

The interactions of man with his environment are so complex that only an ecological approach to nutrition permits an understanding of the whole spectrum of factors determining the nutritional problems that exist in human societies.

The nation behaves well if it treats the natural resources as assets which it must turn over to the next generation increased, and not impaired in value.
This sentence is one of many quotations inscribed on Cox Corridor II, first floor House corridor, U.S. Capitol. It is also inscribed inside the Roosevelt Memorial rotunda at the American Museum of Natural History.

The secrets of evolution are death and time—the deaths of enormous numbers of lifeforms that were imperfectly adapted to the environment; and time for a long succession of small mutations.

Today when the public thinks of the products of science it is likely to think about environmental problems, an unproductive armament industry, careless or dishonest 'scientific' reports, Livermore cheers for 'nukes forever' and a huge amount of self-serving noise on every subject from global warming to 'the face of God'.

Twenty centuries of 'progress' have brought the average citizen a vote, a national anthem, a Ford, a bank account, and a high opinion of himself, but not the capacity to live in high density without befouling and denuding his environment, nor a conviction that such capacity, rather than such density, is the true test of whether he is civilized.

Very old and wide-spread is the opinion that forests have an important impact on rainfall. ... If forests enhance the amount and frequency of precipitation simply by being there, deforestation as part of agricultural expansion everywhere, must necessarily result in less rainfall and more frequent droughts. This view is most poignantly expressed by the saying: Man walks the earth and desert follows his steps! ... It is not surprising that under such circumstances the issue of a link between forests and climate has ... been addressed by governments. Lately, the Italian government has been paying special attention to reforestation in Italy and its expected improvement of the climate. ... It must be prevented that periods of heavy rainfall alternate with droughts. ...In the Unites States deforestation plays an important role as well and is seen as the cause for a reduction in rainfall. ... committee chairman of the American Association for Advancement of Science demands decisive steps to extend woodland in order to counteract the increasing drought. ... some serious concerns. In 1873, in Vienna, the congress for agriculture and forestry discussed the problem in detail; and when the Prussian house of representatives ordered a special commission to examine a proposed law pertaining to the preservation and implementation of forests for safeguarding, it pointed out that the steady decrease in the water levels of Prussian rivers was one of the most serious consequences of deforestation only to be rectified by reforestation programs. It is worth mentioning that ... the same concerns were raised in Russia as well and governmental circles reconsidered the issue of deforestation.

We find that one of the most rewarding features of being scientists these days ... is the common bond which the search for truth provides to scholars of many tongues and many heritages. In the long run, that spirit will inevitably have a constructive effect on the benefits which man can derive from knowledge of himself and his environment.

We must be part not only of the human community, but of the whole community; we must acknowledge some sort of oneness not only with our neighbors, our countrymen and our civilization but also some respect for the natural as well as for the man-made community. Ours is not only 'one world' in the sense usually implied by that term. It is also 'one earth'. Without some acknowledgement of that fact, men can no more live successfully than they can if they refuse to admit the political and economic interdependency of the various sections of the civilized world. It is not a sentimental but a grimly literal fact that unless we share this terrestrial globe with creatures other than ourselves, we shall not be able to live on it for long.

What nature does in the course of long periods we do every day when we suddenly change the environment in which some species of living plant is situated.

When there are too many deer in the forest or too many cats in the barn, nature restores the balance by the introduction of a communicable disease or virus.

While the law [of competition] may be sometimes hard for the individual, it is best for the race, because it insures the survival of the fittest in every department. We accept and welcome, therefore, as conditions to which we must accommodate ourselves, great inequality of environment, the concentration of business, industrial and commercial, in the hands of a few, and the law of competition between these, as being not only beneficial, but essential for the future progress of the race.