In an article in the journal Nature, researchers from Harvard University and the National Science Foundation's Biological Anthropology Program have presented the first study to link throwing ability and the evolution or our ancestors.
Humans are able to throw projectiles at incredible speeds by storing and releasing energy in the tendons and ligaments crossing the shoulder, the researchers discovered, energy that can catapult the arm forward, creating the fastest motion the human body can produce and resulting in very rapid throws.
"Our research demonstrates that the ability to store energy in the shoulder is made possible by three critical changes in our upper bodies that occurred during human evolution," paleobiologist Neil Roach from George Washington University said.
"The expansion of the waist, a lower positioning of the shoulders on the torso, and the twisting of the humerus [the bone in the upper arm] are the key morphological changes that first appeared together nearly 2 million years ago in the species Homo erectus."
The archaeological record suggests that was the time our hominin ancestors began to hunt more intensely, the researchers said.
"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," 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."