Humans learned to throw 2m years ago

2013-06-26 21:51
A Pakistani Muslim demonstrator throws a tear gas shell back towards riot police during their attempt to reach the US embassy during a protest against an anti-Islam film in Islamabad. (Aamir Qureshi, AFP)

A Pakistani Muslim demonstrator throws a tear gas shell back towards riot police during their attempt to reach the US embassy during a protest against an anti-Islam film in Islamabad. (Aamir Qureshi, AFP)

Multimedia   ·   User Galleries   ·   News in Pictures Send us your pictures  ·  Send us your stories

New York - Scientists say they've figured out when our human ancestors first started throwing with accuracy and fire power, as only people can: Nearly 2 million years ago.

That's what researchers conclude in a study released on Wednesday by the journal Nature. There's plenty of scepticism about their conclusion. But the new paper contends that this throwing ability probably helped our ancient ancestor Homo erectus hunt, allowing him to toss weapons - probably rocks and sharpened wooden spears.

The human throwing ability is unique. Not even a chimp, our closest living relative and a creature noted for strength, can throw nearly as fast as a 12-year-old, says lead study author Neil Roach of George Washington University.

To find out how humans developed this ability, Roach and co-authors analysed the throwing motions of 20 collegiate baseball players. Sometimes the players wore braces to mimic the anatomy of human ancestors, to see how anatomical changes affected throwing ability.

The human secret to throwing, the researchers propose, is that when the arm is cocked, it stores energy by stretching tendons, ligaments and muscles crossing the shoulder. It's like pulling back on a slingshot. Releasing that "elastic energy" makes the arm whip forward to make the throw.

That trick, in turn, was made possible by three anatomical changes in human evolution that affected the waist, shoulders and arms, the researchers concluded. And Homo erectus, which appeared about 2 million years ago, is the first ancient relative to combine those three changes, they said.

But others think the throwing ability must have appeared sometime later in human evolution.

Susan Larson, an anatomist at Stony Brook University in New York who didn't participate in the study, said the paper is the first to claim that elastic energy storage occurs in arms, rather than just in legs. The bouncing gait of a kangaroo is due to that phenomenon, she said, and the human Achilles tendon stores energy to help people walk.

Thrusting

The new analysis offers good evidence that the shoulder is storing elastic energy, even though the shoulder doesn't have the long tendons that do that job in legs, she said. So maybe other tissues can do it too, she said.

But Larson, an expert on evolution of the human shoulder, said she does not think Homo erectus could throw like a modern human. She said she believes its shoulders were too narrow and that the orientation of the shoulder joint on the body would make overhand throwing "more or less impossible."

Rick Potts, director of the human origins programme at the Smithsonian Institution, said he is "not at all convinced" by the paper's argument about when and why throwing appeared.

The authors did not present any data to counter Larson's published work that indicates the erectus shoulder was ill-suited for throwing, he said.

And it is "a stretch" to say that throwing would give erectus an advantage in hunting, Potts said. Large animals have to be pierced in specific spots for a kill, which would seem to require more accuracy than one could expect erectus to achieve from a distance, he said.

Potts noted that the earliest known spears, which date from about 400 000 years ago, were used for thrusting rather than throwing.

Read more on:    nature  |  us  |  evolution

Join the conversation!

24.com encourages commentary submitted via MyNews24. Contributions of 200 words or more will be considered for publication.

We reserve editorial discretion to decide what will be published.
Read our comments policy for guidelines on contributions.
NEXT ON NEWS24X

24.com publishes all comments posted on articles provided that they adhere to our Comments Policy. Should you wish to report a comment for editorial review, please do so by clicking the 'Report Comment' button to the right of each comment.

Comment on this story
42 comments
Comments have been closed for this article.

Inside News24

 
/News

Book flights

Compare, Book, Fly

Traffic Alerts
There are new stories on the homepage. Click here to see them.
 
English
Afrikaans
isiZulu

Hello 

Create Profile

Creating your profile will enable you to submit photos and stories to get published on News24.


Please provide a username for your profile page:

This username must be unique, cannot be edited and will be used in the URL to your profile page across the entire 24.com network.

Settings

Location Settings

News24 allows you to edit the display of certain components based on a location. If you wish to personalise the page based on your preferences, please select a location for each component and click "Submit" in order for the changes to take affect.




Facebook Sign-In

Hi News addict,

Join the News24 Community to be involved in breaking the news.

Log in with Facebook to comment and personalise news, weather and listings.