The average food item on a U.S. grocery shelf has traveled farther than most families go on their annual vacations.

In exchange for his first taste of powdered milk, Pascal showed me a tree we could climb to find a bird's nest. After we handled and examined the pink-skinned baby birds, he popped one of them into his mouth like a jujube. It seemed to please him a lot. He offered a baby bird to me, pantomiming that I should eat it. I understood perfectly well what he meant, but I refused. He did not seem disappointed to have to eat the whole brood himself.

Hallie and I... were all there was. The image in the mirror that proves you are still here. We had exactly one sister apiece. We grew up knowing the simple arithmetic of scarcity: A sister is more precious than an eye.

There is a strange moment in time, after something horrible happens, when you know it's true, but you haven't told anyone yet.

But nothing on this earth is guaranteed, when you get right down to it, you know ? I've been thinking about that. About how your kids aren't really YOURS, they're just these people that you try to keep an eye on, and hope you'll all grow up someday to like each other and still be in one piece. What I mean is, everything you get is really just on loan. Does that make sense?" Sure,"I said. "Like library books. Sooner or later they've all got to go back into the nightdrop.

A first child is your own best foot forward, and how you do cheer those little feet as they strike out. You examine every turn of flesh for precocity, and crow it to the world. But the last one: the baby who trails her scent like a flag of surrender through your life when there will be no more coming after--oh, that' s love by a different name.

As a biologist, I can't think of myself as anything but an animal among animals and plant.