Aroldis Chapman stared over his glove at home plate. The Cincinatti Reds were playing the San Diego Padres. Chapman was pitching. After a moment, he gave the catcher a small, almost imperceptible nod then turned, swinging his body into a pitching stance. He regarded the hitter one last time, then tensed, folded, and, in one fluid motion, exploded outwards, throwing the ball faster than could be seen.
There are a lot of strong animals. A draft horse can easily pull four thousand pounds of weight and a fully-grown male chimpanzee can rip your arm out of your socket. But no other animal can throw like a human being. That same chimpanzee can throw a baseball at a measly 20 miles per hour. Chapman’s record-setting pitch was over five times as fast. Nothing in the world even comes close.
A recent study by Neil Roach of George Washington University investigated just how a human evolved to throw that fast. Dr. Roach used motion capture cameras to record and analyze college pitchers as they practiced throwing fastballs. A video of their work in motion can be found here.
They found that the human shoulder evolved to work like a giant slingshot. As a person cocks their arm back the tendons and ligaments in their arms stretch and lock, storing a massive amount of potential elastic energy. When that energy is released it rockets the arm forward in the fastest motion the human body can produce.
This special power likely began to evolve millions of years ago as our primitive ancestors transitioned from a herbivorous to omnivorous diet. “We think that throwing was probably most important early on in terms of hunting behavior, enabling our ancestors to effectively and safely kill big game,” Dr. Roach said. “Eating more calorie-rich meat and fat would have allowed our ancestors to grow larger brains and bodies and expand into new regions of the world—all of which helped make us who we are today.”