How Humans Evolved to Throw a Fastball

By Becky Lang | June 26, 2013 12:02 pm
pitcher throw

Binghamton Mets’ pitcher Zack Wheeler throws a pitch. Credit: Richard Paul Kane / Shutterstock

Pitcher Aroldis Chapman of the Cincinnati Reds routinely throws screaming 100 mile-an-hour pitches—for which he owes credit to a shift in anatomy that occurred about 2 million years ago.

In a study published today researchers have determined how humans are able to throw so fast and so accurately. By using motion capture to study the movements of baseball players’ arms, the team pinpointed the anatomical changes that created modern humans’ strong throw, and they traced the origin of these changes back to Homo erectus.

Mechanics of the fastball

Neil Roach of George Washington University and colleagues recruited 20 players from the Harvard baseball team to construct 3D imaging of the legs, hips, torso, elbow and shoulder from the beginning to the end of a throw.

Roach knew from previous work that the human throw was something distinctive. He had earlier studied throwing mechanics in a group of retired Hollywood chimpanzees and found that, while they can throw with accuracy and are able to toss balls overhand and underhand, their top speed is just 20 miles per hour. Chimps’ shoulders are shortened, rising up toward the head, while human shoulders are more relaxed.

The researchers used the motion capture data to construct a computer model of the physics at work. They found that the key was elastic energy. This energy is stored in stretched ligaments and tendons when the arm is cocked. When the arm is released, the upper arm rockets around and the force causes the elbow to straighten and deliver the ball at high speed.

And they determined that this shoulder rotation is actually the fastest motion of the human body. Professional pitchers can reach a rotation of 9,000 degrees per second. At that speed, if the arm could rotate a full 360 degrees it would complete 25 rotations in one second.

Video courtesy of Nature Video

How throwing evolved

While these body mechanics thrill baseball fans today, they also were crucial to intensifying the hunting ability of ancestral humans.

To replicate our ancestors’ throwing abilities, the researchers outfitted the baseball players with modified braces that restricted their torso and shoulder rotations. As predicted, limiting elastic energy resulted in slower angular acceleration of the arm and a slower throw.

The three anatomical shifts in the upper body that are responsible for modern humans’ fastball, then, were located in the fossil record and found to have evolved in concert around 2 million years ago. The authors suggest that better throwing skills were an advantage in hunting. In turn, better hunting skills meant diets and lifestyles shifted dramatically and may have contributed to the rapid expansion of bodies and brains between 2 million and 200,000 years ago.

“We really don’t have any other evidence as to how that hunting was accomplished. We do know that hunting was intensive and a huge part of our biology,” Roach says. He says the next step is to examine the effectiveness of early projectiles, such as pointed wooden spears as well as rocks. The research is published today in the journal Nature.

 

CATEGORIZED UNDER: Health & Medicine, top posts
MORE ABOUT: anatomy, baseball
  • Jeff Baker

    The shift also could have been related to defense. Being able to throw rocks, nuts, etc. at would be predators with more force would be an effective deterrent. I’ve seen monkeys in the wild (new world monkeys) throw things at people intruding on their territory. They seem to rely more on quantity than quality for chasing possible predators away. But, if you increase the speed of the projectile, it would be a very good deterrent.

    Hominids who could throw with greater force and accuracy would probably be preyed upon less frequently, and produce more offspring.

  • http://sonic.net/~ckelly/Seekay/mtbwelcome.htm RepackRider

    A ballistic calculation is very complicated, but we do it instinctively. Not only is the pitcher’s arm rotation super fast, the release window is measured in thousandths of a second, yet he times it perfectly.

    Professor William Calvin has a theory that the feedback loop of throwing is what caused our brains to expand rapidly. He also has found that the ubiquitous ‘hand axe’ used for millions of years, was a precisely designed throwing weapon.

  • cgosling

    As an ex zoo keeper in the Great Ape House, I can attest to the throwing ability of chimps and gorillas. Their throws are under and side arm. They can throw about fifty feet depending upon what they are throwing, but have poor aim. At close range of about twenty feet they can hit a target more than half the time. Heavier and larger objects such as branches and logs can be propelled fairly accurately at close range.

    Human overhand trowing can be very accurate. As any javelin thrower can attest. We had great sport in college aiming our javelins at plastic bags blowing across a ball field. It our targets were as large as elephants we probably would hit them about 75% of the time at 100 feet. I’ll bet Greek javelin throwers and Masai lion hunters were no slouches.

  • http://blogs.discovermagazine.com Peter Jensen

    Interesting but there is strong evidence that modern ie paleo humans took throwing a significant step further than our nearest relatives neanderthals. Nitrogen isotope bone studies at the Max Planc institute indicate that paleo humans ate significant amounts of fish where neanaderthals ate none. Also the earliest finds of fishing activity in Australia 30,000 years ago indicate consumption of pelagic not just local fish species meaning early man was most likely throwing harpoons at pelagic fish from seagoing crafts. It is generally felt that neanderthals killed mainly by hiding then thrusting spears into prey rather than throwing and that their shoulders were less adapted to throwing than paleo humans. Furthermore paleo humans were using atlatls to enhance throwing even more. There is no evidence neanderthals ever used them.

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