According to a group of scientists who offer new evidence that the classic overhand throw used by baseball players at all positions, and by snowball, rock and tomato hurlers of all ages, is an evolutionary adaptation dependent on several changes in anatomy. They first appeared, the researchers say, around 1.8 million years ago, when humans were most likely beginning to hunt big game and needed to throw sharp objects hard and fast.

No other primate throws with anything comparable to human force. Chimpanzees, who are much, much stronger, pound for pound, than human beings, can throw, as any zoo visitor knows. But the best an adult male can do is about 20 miles per hour. A 12-year-old human pitcher can easily throw three times that fast.

Clearly, the reason is not muscle strength, according to Neil Roach of George Washington University, first author of a report in the journal Nature released on Wednesday. Using motion-capture video, Dr. Roach and his colleagues analyzed the throwing motion of 20 college athletes, who hurled baseballs at a target about 100 feet away, with and without a brace that restricted shoulder motion.

“You’re storing energy in your shoulder,” Dr. Roach said, speaking from Africa, where he was heading to Lake Turkana to look at fossil footprints of human ancestors about a million and a half years old. The storage occurs in the cocking motion, when a thrower brings hand and ball back, preparing to throw. “It works just like a slingshot would. You’re actually stretching the ligaments.

 

Read the complete article at Why Apes Can’t Pitch – Solving a Riddle of Evolution – NYTimes.com