If it's true that our species is alone in the universe, then I'd have to say the universe aimed rather low and settled for very little.
George Carlin

If venereal delight and the power of propagating the species were permitted only to the virtuous, it would make the world very good.
James Boswell

If we continue to address the issue of the environment where we live as though we're the only species that lives here, we'll create a disaster for ourselves.
Gaylord Nelson

If you want to save a species, simply decide to eat it. Then it will be managed - like chickens, like turkeys, like deer, like Canadian geese.
Ted Nugent

In a state therefore of great equality and virtue, where pure and simple manners prevailed, the increase of the human species would evidently be much greater than any increase that has been hitherto known.
Thomas Malthus

In June as many as a dozen species may burst their buds on a single day. No man can heed all of these anniversaries; no man can ignore all of them.
Aldo Leopold

In the world of commercial speech, tobacco advertising bears the earmarks of an endangered species.
Jef I. Richards

Indeed, I was unable to find any evidence whatsoever of the occurrence of a drastic evolutionary acceleration and genetic reconstruction in widespread, populous species.
Ernst Mayr

Indeed, the whole human species is endangered, by nuclear weapons or by other means of wholesale destruction which further advances in science are likely to produce.
Joseph Rotblat

Is it not a species of blasphemy to call the New Testament revealed religion, when we see in it such contradictions and absurdities.
Thomas Paine

It had an enormous impact to the point of the United Nations passing a resolution against the killing and hunting of these whales as they are an endangered species. This was a documentary on the plight of the whales.
Wavy Gravy

It has adopted the geometry most advantageous to the species or, in other words, the most convenient.
Henri Poincare

It has long been a fact familiar to geologists, that, both on the east and west coasts of the central part of Scotland, there are lines of raised beaches, containing marine shells of the same species as those now inhabiting the neighbouring sea.
Charles Lyell

It is a drastic mistake to eliminate the provisions that have to do with the protection of habitat for endangered species. It is my opinion that the Endangered Species Act is 99 percent about protecting critical habitat.
Jim Saxton

It is a pleasant thing to reflect upon, and furnishes a complete answer to those who contend for the gradual degeneration of the human species, that every baby born into the world is a finer one than the last.
Charles Dickens

It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is the most adaptable to change.
Charles Darwin

It is thus necessary to examine all things according to their essence, to infer from every species such true and well established propositions as may assist us in the solution of metaphysical problems.
Maimonides

It would seem to me that by the time a race has achieved deep space capability it would have matured to a point where it would have no thought of dominating another intelligent species.
Clifford D. Simak

It's a moral question about whether we have the right to exterminate species.
David Attenborough

Just as we know rationally that the time will come when each of us as individuals will perish, so we know that our country, our culture and our species cannot exist for ever. Sometime there must be an end.
Harrison Brown