Homo erectus evolved throwing skills two million years ago that help modern Major League baseball pitchers throw fastballs, according to new research published in the journal Nature.
Hunting became more common around 1.8 million years ago, a development which may have been brought about by an adaptation allowing these early hominids to throw objects, including spears, at high speeds.
Humans are the only animals who have the ability to throw at high velocities. While Major League baseball pitchers can top out at speeds around 100 MPH, chimpanzees, our closest competitor, can only reach velocities of around 20 MPH.
Researchers wanted to first understand how baseball pitchers achieve the speeds that they do during pitches, So, the scientists recorded college-level pitchers as they went through their motions.
What they realized was that the windup a pitcher makes preparing for a throw allows the arm to act like a slingshot. Elastic energy is stored in the ligaments and tendons of the shoulder. Halfway through the motion is when shoulder rotation is at its greatest, delivering that stored energy into the pitch - or spear. This stored energy in the shoulder can deliver up to half the energy in a throw, enabling the fastest motion a human body can produce.
The ability to store energy in the shoulder like this first evolved in hominins (human ancestors) two million years ago. Along with the open swing that our arms can produce, unique among primates, is our ability to twist our hips during a throw. That combination of abilities made hunting much easier.
"Success at hunting allowed our ancestors to become part-time carnivores, eating more calorie-rich meat and fat and dramatically improving the quality of their diet. This dietary change led to seismic shifts in our ancestors' biology, allowing them to grow larger bodies, larger brains, and to have more children... It probably also allowed us to move to new environments, such as areas that did not have vegetation to support us before we had the ability to hunt," Neil Roach, of George Washington University, said.
When comparing Homo erectus to modern Homo sapiens, Roach believes that the human ancestor could throw as well as we throw today.
Not everyone agrees with the results, including some scientists who believe that the study did not take enough features of the shoulder into account. Others question how much the adaptation would have assisted the ancient hominids.
"I don't believe that Homo erectus had the broad shoulders that would have given him the ability," Susan Larson, an anatomist at Stony Brook University School of Medicine, said.
