The ability to throw objects at very high speeds is a unique human trait. While our closest living relative, the chimpanzee, can throw only at about the speed of 32 km per hour, professional athletes—for instance fast bowlers in cricket—are known to regularly breach the 145 km per hour mark.
According to a new study, humans have a lot to thank for this ability. When the now extinct Homo erectus species started undergoing anatomy changes, it led to the development of this ability. Researchers claim that this ability had an important role to play in the evolution of humans.
The ability to throw at such fast speed enabled them to hunt. Hunting dramatically improved the diet of early humans, allowing calorie-rich meat. This change in diet allowed early humans to evolve larger bodies and brains, have more children, and travel widely. The researchers add that the development of this ability could have also had a sociological impact, leading to division of labour: while some hunted, others gathered food.
The study, which was published in Nature, was conducted by a group of researchers from the US. To find out how humans developed this ability, they analysed the throwing motions of 20 baseball pitchers at US colleges. They did so by using 3-D cameras and computer animation. They found that when the arm is cocked right before a throw, energy is stored by stretching tendons, ligaments and muscles crossing the shoulder almost like the mechanism of a slingshot. When the energy is released, the arm whips forward to make the throw. This was made possible by three anatomical changes in human evolution that affected the waist, shoulders and arms. All of these changes occurred during the time of Homo erectus.
The researchers write in the journal: ‘These features first appear together approximately 2million years ago in the species Homo erectus. Taking into consideration archaeological evidence suggesting that hunting activity intensified around this time, we conclude that selection for throwing as a means to hunt probably had an important role in the evolution of the genus Homo.’