The Opposable Thumb - Evolution's Gift to Humankind Man's Power Digit Points to Primitive and Positive Rules of Thumb "In the absence of any other proof, the thumb alone would convince me of God's existence." Sir Isaac Newton What's in a thumb? At first glance, maybe not much. No muscles, only two phalanges, a short physique, a distance-challenged banishment to the space bar...the thumb can be seemingly insignificant, especially when compared to its longer, more graceful neighbors. Oh, but how wrong first impressions can (sometimes) be. This digital underdog is arguably the most influential component in the advancement of mankind. I even feel comfortable enough with the physical, symbolic, and communicatory power of the thumb to say that it's the single most influential component in humans' surpassing of apes on the societal scale. Not convinced? Try immobilizing your thumbs for twenty minutes (just twenty minutes, mind you - not for the three million years that the thumb has had to make its mark). Go about your normal business (writing, preparing food, caring for children, bathing, driving, etc.), thumb-less, for those twenty, long, excruciating minutes, and then ask yourself, "Where would humankind be today without fully mobile thumbs?" And against the advice of most good communications experts, I would answer your question with a question of my own: "Would humankind even exist?" Thumbs Down for Monkeying Around Not all thumbs are created equally; that is, not all are fully opposable. In order to grasp this concept, it's best to first define the term "opposable." Loosely defined, "opposable" refers to an object's ability to place itself opposite of another object. In reference to the human thumb, it refers to the digit's ability to lie across the palm, perpendicular to the four fingers. Humans are the only animals on earth with fully opposable thumbs. Primates have good power grips (grasping tree limbs for swinging and rocks for throwing), but lack the level of opposition that would give them a good pincher grip, or fine motor skills. Most primates' thumbs will only oppose to their index fingers, making a two-digit pincher grasp their best hope for peeling that banana. Our thumbs, however, are finely tuned machines. They're longer, more maneuverable, and better controlled than our primate friends' thumbs. Though there are no muscles in the human thumb, it is controlled by five hand muscles and three major nerves. Twenty five percent of the brain's motor power is devoted to the hand, while a generous four percent of the brain's power is devoted to thumb control (so now we know that hitchhikers and film critics really do think before they act). Human thumbs are capable of moving in six different directions, rocketing that shrimpy digit beyond even the best ape thumb. To explain this zoological difference from an evolutionary point of view, consider a study conducted by scientists at the U.S. Department of Energy's Lawrence Berkeley National Laboratory. It, at least partially, debunks the stigma surrounding "junk DNA," and pinpoints a factor that accounts for human's superiority over other primates. These scientists isolated a human gene enhancer (a switch that hangs out near the genes and influences them), named HACNS1, and determined that despite former ideals that named it "junk," it played an important role in the development of the human thumb. To prove this, the researchers gathered the named gene enhancer from a human, a chimpanzee, and a macaque (named in descending order of thumb opposability), coupled the enhancer with a blue dye gene, and injected each into different female laboratory mice. In the mice's fetuses, and surprising result was discovered. The fetuses who inherited the human gene enhancer showed the strongest active blue dye areas - in the hands (front feet), feet (back feet), and throats. The mouse fetuses that inherited the chimp and macaque enhancers showed blue in the same areas, but without the potency of the fetus subjected to the human enhancer. This means that what was once considered "junk DNA" has now been proven to separate us from other primates, in the areas of speech, fully opposable thumbs, and bipedal travel. Just goes to show - one scientific community's junk is another civilization's reason for advancement. Thumbing a Ride on the Evolutionary Express Early man developed opposable thumbs around the same time that he got off of his hands and began to walk upright. And in direct correlation, big toes evolved to support his upright stance and walk (we're still waiting for pelvises to catch up). Not all early human-like primates were our ancestors. Some were more like distant thirty-second cousins, twice removed. But of the ones who were our genetic forerunners, thumbs are believed to have first become opposable digits as part of either the Homa habilis or the Homo erectus group members. Homa habilis, or "Handy Man" lived two million years ago and was one of the first pre-human earth inhabitants to develop a semi-opposable thumb (all the better to create and use tools with). Homo erectus was the legendary first biped. He lived two to three million years ago, and also boasted a set of semi-opposable thumbs (all the better to build fires with). More recently, Neanderthal man sported an opposable thumb with a longer distal phalanx (top thumb bone) than ours. There was also healthy compensation for the opponeus pollicis muscle (muscle controlling the thumb), making it probable that this barbaric predecessor of Homo sapiens (us) had one heck of a power grip (better for tackling and killing wild game and dragging their girlfriends into man-caves). Our thumbs are adaptations. As the human genome was being fashioned over millions of years, humans with genetic mutations that gave them more opposable thumbs than their peers had higher survival rates, and subsequently got more action in the reproduction department. This means that the "good thumb" genes were passed on, creating more and more humans with good thumbs - hence the evolution of the opposable thumb (and a revolution in the direction of thumbs that were suddenly very sexy). One, Two, Three, Four, I Declare a Thumb War After the human thumb evolved to the digit that it is today, its value was calculated as priceless. It not only held mythical powers, but was used to communicate sentiments and as collateral against bad behavior. Julius Caesar made a name for himself by collected a few thumbs for himself. Prisoners' thumbs were amputated so they could no longer bear arms after their releases. This tradition was carried on in other wars and was also utilized to punish escapee slaves in the West. Caesar saw the value of the thumb. He could have chosen to pluck out eyes or cut off toes, but instead, he stripped one of man's most powerful assets. He was wise enough to see that the thumb is the Achilles' heel of the hand - invaluable in the having, utterly destructive in its absence. Much of the thumb's more recent lore comes from England and Scotland. From 1350 to 1800, a thumb folded inside a closed fist acted as a deterrent to evil, sorcery, witches, and general evil. The thumb was thought to take on strange sensations in the presence of danger. An example of this thinking can be found in William Shakespeare's Macbeth: "By the pricking of my thumbes, Something wicked this way comes." This superstition is similar to finger-crossing for luck today. In the middle 17th century, gladiators' fates were determined by the thumb positions of the audience. Thumbs hidden inside palms indicated dissatisfaction with the gladiator's performance, and thoughts that he should be put to death. Outstretched thumbs showed wishes to spare the life of the gladiator. During that same period, two thumbs-up were adopted to show praise. Beginning in 1208, and lasting through the late 1800s, deal-makers wetted their thumbs with saliva and pressed their thumbs together to "seal the deal." Common verbiage to accompany this action was, "Here's my thumb on it." Soon after, drivers used the thumbs-up symbol to greet other drivers and pedestrians, while trolling bachelors could identify a widow by a ring worn on her thumb. In the mid 1900s, the thumb in the air was embraced as the hitchhiking symbol. And since the English settled the new world, many of these thumb signals survive today. But be warned, in countries other than England and The United States, I wouldn't recommend using the thumbs-up gesture. It's considered obscene in many other places; equivalent to flipping the Minnesota bird. Thumbelinas of the Digital Revolution Just when we might have thought the thumb has evolved and stalled, the "digital" age comes up with Generation Thumb. Generation Thumb, defined as including those born after 1985, is displaying thumbs of uber-capable proportions. Edward Tenner, a science historian at the Smithsonian Institution, points to the incredibly agile, larger, and more muscular thumbs of this generation. Japan's adolescents and teens led the revolution by being dubbed the nation with the most advanced thumbs in the world, thanks to their elevated use of texting devices. Japanese youth have even taken to using their thumbs for tasks previously appointed to the index finger, like ringing doorbells and pointing to items of interest. Tenner cites societal changes in the revolution of the thumb. He notes that the thumb experienced a dawn when the musical keyboard was invented, but then fell out of fame...until it was rediscovered as a method for "digital" communication. The benefit of this evolution is, of course, arguable among different groups, including those who maintain that being "all thumbs" isn't all bad. Putting Body Language under your Thumb We're all familiar with thumbs as voluntary communication devices. If you want to indicate that someone's "outta here," you'll throw a thumb over your shoulder. If you want to tell your daughter, from the bleachers, that she nailed the double back flip, you might extend a "thumbs up." Or otherwise, use the "thumbs down" or "sideways (iffy) thumb" to indicate disapproval or uncertainty. But did you know that thumbs are also great involuntary indicators of power and intention? Consider these thumb signals when interacting: ? Hands in pockets, with thumbs pointing toward reproductive organs (or thumbs in belt loops or the waistband) tell us that the person (usually male) feels confident in his virility, and has a desire to attract attention to his sexual parts. ? One thumb in a pants pocket, with the rest of the fingers exposed, tells us that a person (usually female) wants to draw attention to her sexual availability. ? Using a thumb for tasks normally assigned to the index finger (like pushing an elevator button) denotes a feeling of superiority. ? A thumb tucked inside a palm means a temporary loss of confidence, having no intention of acting right now, or that the person is holding something back. ? A hand or index finger pointed at someone else, with the thumb in the air, indicates that the speaker feels superior to the receiver. ? A hand or index finger pointed, with the thumb to the side, means that the speaker feels that he or she is of equal standing with the receiver. ? A handshake in which both persons' thumbs are pointed upward means good rapport and equal standing. ? When a speaker's thumb is pointed toward himself, be warned that the agenda is all about him; he feels power and entitlement. ? A thumb held tightly against the hand tells us that the person doesn't feel like taking any action right now. ? A thumb held at a short distance from the hand denotes caution and insecurity. ? A thumb held at a medium distance from the hand tells of stability and reasonable confidence. ? A thumb held at a large distance from the hand usually indicates aggression, extreme confidence, or readiness for action. In general, watch the angle of the thumb and the direction in which it's pointing. If it's pointing upward, its owner is likely feeling superior. Also, the thumb will naturally point toward the part that its owner feels is most valuable at that moment. The more exposed and vulnerable the thumb appears, the less vulnerable the user of that thumb is feeling. It's a paradox, but so is the thumb - the smallest, but most powerful, digit. Opposable Thumbs Met with no Opposition The thumb is our most powerful digit - it's definitely "thumbody special." Not only has it impacted our lives, arguably more than any other evolutionary element, but it is the most powerful communicator of all of our digits. Without the thumb, there may be no written communication, no paintings, no sculpture, no music, no electronics...no industry. Perhaps, deep within us, we know how precious the thumb is to our long-time survival, and how long mankind suffered before it was gifted with this indispensable digit. Maybe we innately know how our thumbs have historically been threatened, and value them by hiding them when we, ourselves, feel threatened. Maybe, also, that's why we display them brazenly when we are confident - because we know that what we are saying is truth, and have no fear. I hope that you have adopted a newfound appreciation for the little digit with big influence. Its function makes you uniquely human - and now that you know how it speaks to others, you are uniquely equipped to speak and read the language of the thumb. By the way, if you're still holding your thumbs for that experiment in the beginning of the article, you may have them back.
