We study the injustices of history for the same reason that we study genocide, and for the same reason that psychologists study the minds of murderers and rapists... to understand how those evil things came about.

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

Besides justifying the transfer of wealth to kleptocrats, institutionalized religion brings two other important benefits to centralized societies. First, shared ideology or religion helps solve the problem of how unrelated individuals are to live together without killing each other—by providing them with a bond not based on kinship. Second, it gives people a motive, other than genetic self-interest, for sacrificing their lives on behalf of others.

The metaphor is so obvious. Easter Island isolated in the Pacific Ocean — once the island got into trouble, there was no way they could get free. There was no other people from whom they could get help. In the same way that we on Planet Earth, if we ruin our own [world], we won't be able to get help.

Some people have much more pull than other people. But when I say that the public has ultimate responsibility, I'm not saying it in a moral sense. I'm just saying it in the sense of what is it that's really going to bring change.

Our biggest threat is not an asteroid about to crash into us, something we can do nothing about. Instead, all the major threats facing us today are problems entirely of our own making. And since we made the problems, we can also solve the problems.

We scientists have fantasies of being uniquely qualified to make great discoveries. Alas, reality is cruel: most of us are replaceable. For the vast majority of scientific contributions, if scientist X hadn't achieved it that year, scientist Y would have achieved the same result or something very similar soon thereafter.