For all the frightening strength primates are capable of, many are downright terrible when it comes to throwing things with force. Such is not the case for the relatively weak and hairless Homo sapien, which is capable of hurling anything from snowballs to hunting spears with ferocious velocity.
Take Aroldis Chapman, a gifted pitcher for the Cincinnati Reds. He once threw a heater clocking in at a staggering 105 mph — the fastest baseball pitch on record:
So why are humans elite when it comes to making objects zip through the air, and apes are not? Humankind's physiological advantage is the subject of a new study by Neil Roach of George Washington University. He used motion sensors to analyze the throwing motions of humans, as well as the awkward overhead flings of the much stronger chimpanzee.
He discovered that the dirty secret to our throwing prowess isn't strength; rather, it lies the human body's unique ability to cock a baseball or football back before releasing it at its most optimal point. "You're storing energy in your shoulder," Dr. Roach tells The New York Times. "It works just like a slingshot would. You're actually stretching the ligaments."
As the Times points out, "several developments in anatomy allowed humans to throw this way," including "a waist that allows twisting and a relatively open shoulder, compared with those of other primates like chimpanzees." Our wind-up transforms our otherwise unimpressive bodies into devastating catapults.
Roach thinks that these anatomical features began evolving 1.8 million years ago, and allowed our physically meek ancestors to chase much larger — and therefore more dangerous — animals for food. "Throwing projectiles probably enabled our ancestors to effectively and safely kill big game," Roach tells Nature. Consuming calorie-rich protein in turn may have helped the bodies and brains of early hominins like Homo erectus to evolve.
If true, it would certainly help explain why a 12-year-old little leaguer is capable of launching a baseball three times harder than even the strongest chimp — although the throw itself may not be an innate human action. "It's like walking," says David Carrier, a biomechanics researcher at the University of Utah who was not involved with the study. "You have to practice."