Your thumbs won't be dumb if they learn a few new skills

By Chris Oliver
Advertiser Staff Writer

Fun thumb facts The humble thumb has nine individual muscles and is controlled by three main hand nerves. Rule of thumb is thought to be an old carpenter's measurement, one of many body-related ones such as the foot and the hand (still the unit of measurement for horses). The length from thumb joint to thumb tip is about one inch. A thumb index is a series of rounded notches cut into the fore edge of a book, head to tail, back to front, used for dictionaries and Bibles. "Under My Thumb": unforgettable, politically incorrect lyrics by the Rolling Stones. "Two Thumbs Up" was made famous by the late Gene Siskel and Roger Ebert, their way of advising that a movie was worth seeing. "Thumb Wars" is an animated spoof of "Star Wars," starring Loke Groundrunner and Princess Bunhead. Thumb Wrestling, an ancient game from China or perhaps Rome, is still played by kids on long automobile journeys.

"Snake," an anxiety-provoking game that plays out on my phone's tiny display, requires thumb dexterity, a new-millennium skill. Cell phones, text-messaging and, of course, computer games all rely heavily on thumb usage.

Personal digital assistants now have tiny keyboards designed just for thumbs. Techno-geeks can even buy "thumb stabilizers" to reduce stress on those poor old opposable digits.

The marketing possibilities are mind-thumbing.

That's right: After years of dull assignments — ringing doorbells, being hit by hammers, blocking holes in Dutch dikes — thumbs are back.

A recent study by Motorola and research by Sadie Plant of Warwick University in Britain showed that young people in Japan had developed "unusual thumbing powers," including typing with thumbs alone.

If behavior precedes anatomy, then, could future generations possibly grow bigger thumbs? Evolve a different bone structure? Could the thumb become a sex symbol, an anatomical appendage whose size does matter?

"Yes and no," said Caroline Blanchard of the University of Hawai'i's Pacific Biomedical Research Center. "Bones can be strengthened by use. Note that in right-handed baseball pitchers, the upper arm bones tend to be thicker than those of the left arm, (and) certainly muscles are strengthened by use. Thus, increased thumb use should have effects on relevant thumb muscles and might even affect thumb bones."

So, a behavior change could lead to a slightly different kind of thumb, but Blanchard points out that learned traits are not passed on.

In other words, the thumb won't evolve as a result of cell-phone use unless people with genes for dextrous thumbs pass on more genetic coding than folks with clumsy digits.

"There would have to be some sort of adaptive value such as more offspring ... for those using the thumb in a particular fashion," Blanchard said.

How old is the human hand as we know it? Blanchard points to evidence presented by Randy Susman, an anatomist with Stony Brook University in New York. "Susman's studies indicate that tool-making practices of early hominoids two million years ago required a more or less human-like hand, suggesting that the hand, as we know it, had developed by then."

Thumbs may be stubby, but they weren't always boring.

In ancient Rome, gladiators lived or died by the emperor's thumb.

In medieval Europe the thumbscrew, a torture device, crushed the thumbs of unlucky victims to extract confessions.

Tom Thumb and Thumbelina were just born before their time.

And babies have long known that a thumb is far more than just another moveable body part.

Of course, you need more than a nifty thumb to rock the house the way John Mayall did that night. But behind his raucous harmonica and awesome keyboard, underneath the fine riffs of Buddy Whittington's blues guitar, and above the heady drum solos, the bass notes kept a steady rhythm flowing — thanks, in part, to the digital dexterity of the thumb.