GW Research Spring 2014 Edition

Unwinding the Origins of Throwing

Unwinding the Origins of Throwing
(Original Art: Nature/Laszlo Meszoly; Illustration: Jesse Winston, John McGlasson.)

Key anatomical changes first appeared together 2 million years ago

May 01, 2014
Modern man may have perfected the fastball, but it was our ancestors nearly 2 million years ago who likely were the first to throw it, according to a recent study.

The ability to throw objects with speed and accuracy requires a constellation of anatomical features that evolved over time and first came together around 2 million years ago in the early human species Homo erectus, researchers reported in June in the journal Nature.

The timing, they write, coincides with archaeological evidence of early hunting activity. The study is the first to trace the origins of powerful throwing and to propose a link to the dawn of hunting, a development that sparked a seismic shift in human history, says lead researcher Neil Roach, a postdoctoral scientist at GW’s Center for the Advanced Study of Hominid Paleobiology.

“Humans are amazingly good throwers,” Dr. Roach says. By comparison, the strong and athletic chimpanzee—man’s closest living relative—throws at a speed about one-third that of a 12-year-old boy, he says. The difference, the researchers write, is in evolutionary changes to the shoulder, arm, and torso that enable human shoulders to gather and release energy like a slingshot.

To identify the mechanics involved, the research team— which included scientists from Harvard University, where Dr. Roach conducted the research as a doctoral student, and the National Centre for Biological Sciences, in India—analyzed the throwing motions of 20 males, most of whom were college baseball players.

Using a 3-D motion capture system, like those used to make video games and animated movies, the researchers recorded movements as participants threw baseballs at a target, then again while wearing a brace designed to limit their motion to mimic that of human ancestors.

“What we discovered was that during the throwing phase, in which the arm is pulled backwards, humans are storing elastic energy by stretching the ligaments, tendons, and muscles that are crossing the shoulder,” Dr. Roach says. Releasing that energy whips the arm forward, generating a high-velocity throw.

That ability would have been vital to hunting, an important development that was beginning to intensify around the same time the anatomy for powerful throwing came together in Homo erectus, Dr. Roach says.

“Hunting really changed who we are and the way that we, as organisms, interact with the world,” he says. “The additional calories that meat and fat provided would have also allowed Homo erectus to grow larger bodies, bigger brains, and to have more babies—all of which helped make us who we are today.”

But exactly what these ancestors were throwing 2 million years ago remains a question, and an area where the team is turning their attention.

Pointed stone projectiles date to only around half a million years ago, Dr. Roach says, and before then the only weapons available would have been rocks and sharpened wooden spears. The team now plans to study how effective these early projectiles would have been for hunting. —Danny Freedman


Watch Dr. Roach explain the findings at go.gwu.edu/throwing