MVP pitcher Justin Verlander is known for consistently throwing heat for the Detroit Tigers. In a study published this week, scientists learn how professional pitchers can throw with such high velocity and what this skill meant in our evolution. Photo by Don Emmert/AFP/Getty Images
When it comes to the ability to pitch a 90 mph fastball, humans are unmatched. Sure, chimpanzees can throw, but only at about 20 mph, a speed that wouldn't land them a spot on a Little League team, said Neil Roach, a postdoctoral researcher in George Washington University's Center for the Advanced Study of Hominid Paleobiology.
"If you look at any Little League baseball game in any town in America, you can find a 12- or 13-year-old kid that can throw 60 or 70 miles per hour on the mound at that game," he said in a video produced by George Washington University. "And that to me is really remarkable performance. It's what we all are capable of doing as opposed to the best athletes among us."
Roach and Dan Lieberman, professor of biological sciences at Harvard University, believe that early humans evolved this skill for hunting -- specifically for hurling spears or rocks at small animals to kill and capture food. Their research is published in this week's edition of the journal Nature.
To study the mechanics of throwing, they placed sensors on the arms and torsos of a group of college baseball players and then recorded their movements in three dimensions. You can see an explanation of the experiment below.
Neil Roach and Dan Lieberman explain how humans developed our powerful throw. Video produced by Harvard University
Our arms act like small catapults, Lieberman said in a video from Harvard University. When the pitch starts, the player twists his torso to the side, causing his arm to draw as far back as he can. That motion creates and stores the elastic energy needed to launch the ball, Lieberman said.
"We're the only creature in the world that can throw really hard and really fast at the same time," Lieberman said -- and we do it pretty accurately. "When you throw, you cock your arm back, and when you do that you're stretching, basically loading your upper arm like a catapult or a sling. And what we discovered is about half the energy you impart to a ball or a spear when you throw it comes from that elastic energy storage."
Throwing is the fastest motion the human body is capable of producing, Roach said, thanks to that elastic energy.
But in order to wind up for that powerful pitch, three major changes in our anatomy had to occur, the authors determined. First, we had to develop a longer torso, a product of walking upright seen in our australopithecine relatives 4 million years ago. And that torso had to be able to pivot independently of our lower body.
Second, we needed broad, flat shoulders so our arms could create a right angle, allowing our shoulders to more effectively store and release elastic energy. Try scrunching your shoulders toward your chin and throwing overhand; you'll see why our australopithecine ancestors had a hard time. Finally, the humerus, the long bone in the upper arm, rotates where it meets the shoulder socket, something called humeral torsion. That "twist" translates to how far you can cock your arm back, Lieberman said in the video, which meant you could store more energy to impart to the ball.
And while some of these characteristics appear in early Australopithecus, all three elements appear together in Homo erectus, an ancestor that appeared about 2 million years ago, Roach said. Roach and Lieberman believe that by developing our throwing power, we were able to take down larger animals with rocks and spears -- a real game-changer.
Neil Roach is looking for how humans' throwing power explains early hunting. Photo by William Atkins/GW University Photographer
"Hunting matters because more calories in your diet means you can build bigger bodies and bigger brains and have more babies, all of the things that matter for evolution," Roach said.
Rick Potts, director of the Smithsonian's Human Origins Program, doesn't entirely agree with Roach and Lieberman's theory. The first evidence of spears, our most powerful primitive weapons, appeared 400,000 years ago in Europe, 1.5 million years after the emergence of Homo erectus, Potts said. Homo erectus could have thrown rocks to drive away predators, he said, but the tools and skills for hunting large game didn't appear until later.
"Once you get to large animals, if you don't hit it right where you want to every time, you just enrage the creature," Potts said, adding that even professional pitchers miss the catcher's glove half the time. "We don't see points that could penetrate hide until much later in archeological records."
Also unclear is when exactly our shoulders settled into the right position to throw a weapon, said Owen Lovejoy, professor of anthropology at Kent State University, so it may not have been a primary driver in the selection process for Homo erectus. And a lot more goes into hunting than just physiology, he added.
"I wouldn't rule out the role of the brain in a human's ability to throw," he said.
Roach says the team is continuing their research, searching for evidence of early projectiles to explain pre-spear hunting, and to determine how or if early humans could have taken down prey by throwing rocks or sharpened sticks.
And while modern throwing skills are largely recreational now, Roach said, understanding better how the shoulder moves and stores energy during a throw will help prevent injury for modern athletes, who sling high-speed pitches dozens of times every game.
"What happens is that people actually injure their shoulders and they injure their elbows," Roach said. "So at the end of the day, the ability that we have to store elastic energy in our shoulder makes us great throwers, but it's also injuring us."
Watch VideoVideo by George Washington University.