I've worked very hard in this book to keep the lines of communication open. I don't want to turn someone away from this information for partisan political reasons.

History as well as life itself is complicated -- neither life nor history is an enterprise for those who seek simplicity and consistency.

Forced to choose between limiting population or trying to increase food production, we chose the latter and ended up with starvation, warfare, and tyranny.

The adoption of agriculture, supposedly our most decisive step toward a better life, was in many ways a catastrophe from which we have never recovered.

AIDS and malaria and TB are national security issues. A worldwide program to get a start on dealing with these issues would cost about $25 billion... It's, what, a few months in Iraq.

We're uncomfortable about considering history as a science. It's classified as a social science, which is considered not quite scientific.

Biology is the science. Evolution is the concept that makes biology unique.

Technology has to be invented or adopted.

Rhino-mounted Bantu shock troops could have overthrown the Roman Empire. It never happened.

Human societies vary in lots of independent factors affecting their openness to innovation.

Why did human development proceed at such different rates on different continents for the last 13,000 years?

What is the point of roaming the world when it's the same misery everywhere?

No! I need to go home, " I say, but then the realization comes: My mother was my home. My mother is dead.

Christianity in its ideas was never the art of the possible.

Not he who has much is rich, but he who gives much.

Through high school, college, graduate school and beyond, I had a number of relationships that were wonderful.

The other side is beyond knowing. You cannot know what you experience on the other side, here. Wisdom is beyond the grasp of the conscious mind.

Groucho: You know I think you're the most beautiful woman in the world? Woman: Really? Groucho: No, but I don't mind lying if it gets me somewhere.

We tend to make the thing in the way the way.

Students are often taught when to use a particular method and how to use it, but not how to effectively write up their research plan and then later their research results.

I'm happy with what I've achieved.