I regret not working harder to create true friendships with other couples, not seeking out people with whom to go do things and go places - people with whom to have a few crazy, memorable bonding adventures.

When a trait is universal, evolutionary biologists look for a genetic explanation and wonder how that gene or genes might enhance survival or reproductive success.

For humans and animals alike, truly vigorous, wholehearted, spontaneous play is something of a biological frill.

Scientists who study play, in animals and humans alike, are developing a consensus view that play is something more than a way for restless kids to work off steam; more than a way for chubby kids to burn off calories; more than a frivolous luxury.

The discovery of HIV in 1983 and the proof that it was the cause of AIDS in 1984 were the first major scientific breakthroughs that provided a specific target for blood-screening tests and opened the doorway to the development of antiretroviral medications.

Our society has lost confidence in the power of reason, except perhaps scientific reason.

I started out wanting to be a naturalist. My obsession in my youth was with bird-watching. I collected things, I spent a lot of time outdoors. I only vaguely realized that science was a little more than natural history, but by then I was hooked.

Yes, from the time I was in junior high school I decided I wanted to be a chemist. I didn't quite know what a chemist was, but I kept it up and got my Ph.D. in physical chemistry.