By Chester Campbell
This all came to mind as a result of making the discovery a couple of mornings ago that I had somehow managed to inflict three little cuts on my right thumb, up near the nail. I first thought maybe they would act nice and just go away. Not so. I finally gave up and used a Band-Aid. I had to wrap it over the top of my thumb, sticking to the nail.
I quickly discovered why God made thumbs. It is practically impossible to push a button through a tight buttonhole without a thumb. Try picking up a glass. Or write with a pen or pencil. Okay, some people, including our sixth-grade grandson, use a wild gripping method that doesn't make good use of the thumb for writing. But you get the idea.
So I got on Google to check out this marvelous digit. We humans share opposable thumbs with most other primates, like apes and gibbons which have them on both hands and feet. Opposable means we can touch each of our fingers with our thumbs. It's what gives us the dexterity to manipulate tools or do our knitting. We don't need them on our feet since we walk standing up.
The thumb is what gives us the ability to grip objects. People who classify things (why they do this is another subject) use "power" and "precision" to separate the way we grip. Power is the way we grip a hammer, while precision is what we do when writing with a pencil or picking up a jar using fingertips alone.
We use the thumb metaphorically to express our opinions for goor or ill. We give thumbs up when we approve of something. A thumbs down means no go. Interestingly, the popular belief is that these hand signals derived from the days of Roman gladiators. When a gladiator was defeated, the crowds in the Coliseum gave a thumbs up to spare his life, or a thumbs down to have him run through by the sword of the victor.
A scholarly article on Wikipedia debunks this idea. After much research into writings from the era and various translations, he concludes that a thumbs up really meant kill the dude, while waving the hand with the thumb in a fist covered by the fingers signified a desire to spare his life.
A once popular use of the thumb was to signal drivers that you wanted a ride. This led to the term "hitchhiker's thumb," which is defined as a "distal hyperextensibility of the thumb" when it leans back nearly 90 degrees while doing the hitchhiker sign. According to a 1953 study, the incidence of the trait in the US was 24.7% in whites and 35.6% in blacks. This was probably one of those federal projects that some congressman "earmarked" to bring a bunch of bucks into his district. In the interest of full disclosure, I happen to be in that 24.7%.
A reference to a Human Accelerated Region "that may have contributed to the evolution of the uniquely opposable human thumb" led me to an article discussing the human genome, then to another on mitochondrial DNA. I soon found myself wandering far afield from my bandaged digit. Incidentally, the thumb is used in Medical gibberish with the adjective form "pollical."
And with that bit of esoteric trivia, I'll get my thumb off the space bar before somebody gives me the thumbs down for good. By the way, next time you're in Iran, Iraq or Sardinia, it would not be a good idea to use the hitchhiking gesture. Over there it means "up yours!"