A billion could live off the earth; 6 billion living as we do is far too many, and you run out of planet in no time.

No one who has experienced the intense involvement of computer modeling would deny that the temptation exists to use any data input that will enable one to continue playing what is perhaps the ultimate game of solitaire.

Imagine a survivor of a failed civilization with only a tattered book on aromatherapy for guidance in arresting a cholera epidemic. Yet, such a book would more likely be found amid the debris than a comprehensible medical text.

An inefficient virus kills its host. A clever virus stays with it.

What we have lived through, the 20th century, has been like a great party. Adults now have had the best time humanity has ever had. Now the party is over and the Earth is reckoning up.

There is little evidence that our individual intelligence has improved through recorded history.

The world has not warmed up very much since the millennium.