My latest Mind and Matter column in the Wall Street Journal is about parabolas, the evolution of throwing and angry birds:
The spectacular trajectory of the Angry Birds computer game, from obscure Finnish iPhone app to global ubiquity-there are board games, maybe even movies in the works-is probably inexplicable. Of course it's cheap and charming, but such catapulting success must owe a lot to serendipitous, word-of-mouth luck. Yet, prompted by my friend Trey Ratcliff, who created the gaming-camera app 100 Cameras in 1, I've been musing on whether there's an evolutionary aspect to its allure.
To play Angry Birds, you must use a catapult to lob little birds at structures in the hope of knocking them down on pigs. It's the verb "lob" that intrigues me. There is something much more satisfactory about an object tracing a parabolic ballistic trajectory through space towards its target than either following a straight line or propelling itself.
Predicting parabolas is something humans just seem to find intriguing. How else do you explain golf? Or the awe in which we hold good quarterbacks in football and good spin bowlers in cricket? Our bodies are uniquely good at throwing things at targets. The trajectory must be prefigured in the brain before the projectile leaves the fingers. Our shoulders rotate, our scapulas slide, our pelvises pivot, our arms flex and our fingers extend.
With the exception of the archer fish, which knocks insects off leaves with well-aimed jets of water, no other animal uses parabolic trajectories. A chameleon darts out its tongue in a straight line. A dog likes catching a ball but could not begin to throw it. No animal has a throwing limb like us. A chimpanzee chucks rocks and branches when angry but usually underarm and with the random aim of a human toddler. The closest any bird-angry or not-comes to throwing is the Egyptian vulture trying to break ostrich eggs by strewing rocks in their general direction. The parabolic ballista is ours alone.
Until 10,000 years ago, most or even all human beings relied on this talent for gathering at least some of their food-by killing it at a distance. With the arrow, the spear thrower, the blowpipe, the boomerang, the sling, the harpoon and the thrown rock, we were killing prey from fish to birds to mammoths. Not to mention each other.
The biologists Paul Bingham and Joanne Souza have argued that the ability to deal death at a distance was crucial to the development of society, because with a well-aimed throw it was now easy for even weak individuals to punish those who abused their position. Not for nothing did Damon Runyon call guns "equalizers.'"
Yet throwing projectiles may be a feature of comparatively recent human evolution. For our own race of Homo sapiens, throwing rocks dates back only 80,000 years or so in Africa. By contrast, the skeletons of Neanderthals-our doomed cousins who lived in Europe till 30,000 years ago-show a high frequency of fractures that roughly mirror the kinds of breaks rodeo riders sustain. This suggests that they were getting close to their big-game prey, stabbing horses, reindeer, bears and rhinos with spears, rather than throwing javelins at them.
Moreover, modern baseball pitchers show a characteristic backward displacement of the shoulder joint-usually only on one side. So do the skeletons of early modern European hunter-gatherers, according to Jill Rhodes and Steven Churchill of Duke University, but not Neanderthals. They apparently had no "throwing arm."
Imagine how much keener the joy of the throw if the prize was food after a day of hunger. No wonder we still love to experience the thrill of a well-launched parabolic projectile-even a cartoon of an angry bird.