You Learn Something New Every Day

This is not something I'd thought about before, but if given a choice by my kidnappers over which finger they would cut off and send to the cops to prove they have me and to hasten the ransom, I would have said the pinky on my left (non-dominant) hand.

Turns out that's the wrong choice.

...you want to give up the first finger on the hand you don't use for writing.

A lot of people think the first, pointing finger is the most important one they have. Wrong! Once it's gone, the other three compensate for it quite well. The second finger, for instance, is already pretty similar to the first finger.

The pinky is actually incredibly important, and it's a keeper. Basically, the reason humans have "opposable" thumbs — the springboard of our evolution from being just another ape —  is that the thing doing the most opposing is the little finger.

According to the assistant chief of hand surgery at the NYU Hospital for Joint Diseases, the little finger does a disproportionate amount of gripping, while all the other guys are its helpers:

The other three digits—the index, the thumb and the middle finger—they fine tune where the tool goes. So if you have your little finger amputated, you're going to lose a significant amount of grip strength when holding everyday small objects. When you talk about utensils—like knives and forks—most of that stuff is fine manipulation rather than strength, so you're typically using the other three digits. You use the thumb, the index and the middle fingers in order to hold a spoon, or to hold a fork, or even to hold a pen and write things.

Take this test: Try doing pull-ups without using your little fingers, and then do the same without your first fingers, and you'll get an idea of how disabling it is to lose the pinky. A New York Times writer described the experience in 2008. It's not fun.

The article also goes on to answer the question "What if the kidnappers offer you the choice of losing a toe?"

The answer isn't as clear-cut as which finger, but I'll let you learn that for yourself.