A two-and-a-half-year-old is pretty experienced at making a mess, anyway.

People that don't want to get down to the business at hand. Instead of just doing less, we have to find ways of doing more with less. That's the key to the future.

We should educate more women and girls. Because that is the surest route to controllably, manageably reducing the human population. Educated women have fewer kids. And the kids they do have are better cared for and are more successful. As I like to say, it's not one thing that we need to focus on. It's everything all at once.

I tell personal stories associated with aspects of the theory, and I hope they are interesting and compelling. I don't feel you're going to change a grownup's mind in one reading. People have to be exposed to scientific ideas over and over again for years. It's also not a textbook.

Evolution is the fundamental idea in all of life science, in all of biology. The key to our being here now is time, 4.54 billion (Earth) years of time. Nuclear fission wasn't discovered until long after Charles Darwin and Alfred Russell Wallace published their original books and papers, for example. Our ability to measure atomic masses wasn't developed until long after their deaths. These features of nature enabled us to reckon the age of the Earth and compare it with speciation rates here.

The most serious problem facing humankind is climate change.

To leave the world better than you found it, sometimes you have to pick up other people's trash.