From spears to baseball: the evolution of throwing

A US-led study has compared modern baseball players with archaeological records to conclude it’s highly likely that humans evolved physical characteristics needed to throw a long distance.

The researchers believe the physical changes match the timing of humans being able to throw weapons such as spears. That proved a major change in human behavior as it allowed people to develop a meat diet (leading to further biological improvements) and allowing them to move to locations that didn’t necessarily have a lot of edible vegetation on hand.

The team, led by Neil Roach of George Washington University, explored the way humans generate energy for throwing, noting that leading human athletes can throw objects at more than four time the speed of a chimpanzee.

The researchers used motion capture camera to record college baseball players in action. They noted that around half the throwing power comes not from muscles, but from ligaments and tendons around the shoulder, which stretch, store and then quickly release elastic energy.

These characteristics seems to coincide with changes in hominins around two million years ago, the time at which it seems hunting with thrown weapons became more common.

However, it’s not necessarily a home run for the researchers. Jill Rhodes of Drew University noted to the BBC that fossils of homo erectus suggest they differed in two ways from today’s athletes: they had a different angle at the shoulder joint from today’s humans, and there’s no sign of homo erectus asymmetry in the angles on the right and left shoulder joint, as would be expected from a creature with a “natural” throwing arm.