This is where the whole ape-descended thing reveals its worth, I thought madly. Sucks to be you, quadruped. Opposable thumbs – don’t leave home without them.

Love is a bird’s nest of emotion that I used as a basket to store picnic items like apples, cheese, wine, and finger foods like thumbs and pinkies.

Would it save you a lot of time if I just gave up and went mad now?

Put your middle finger and your thumb together. And make it snappy.

I call my thumb Napoleon, because I rarely ever lose a thumb war. Also because my thumb’s so small, and I wear a tiny funny hat and cape on it.

My rule of thumb for hitchhiking is: stick it up straight and proud and make if visible to all drivers.

I put up my thumb and it blotted out the planet Earth.

I had learned that a dexterous, opposable thumb stood among the hallmarks of human success. We had maintained, even exaggerated, this important flexibility of our primate forebears, while most mammals had sacrificed it in specializing...