Left-handed Stone Age men

I read something interesting the other day: there is evidence that lefthandedness was fairly common in the Stone Age. University researchers looked at 507 hand prints in 26 caves in France and Spain that were painted between 10,000 and 30,000 years ago.

They found that 23% were prints of right hands, indicating that they were made by left handers - as they would have painted the cave wall using their left hand and done the print with their non painting hand. Today, only about 12% of us are lefties.

But, then I've also read that tools found in Stone Age times were sharpened equally for left and right hand use, suggesting left handedness was far more prevalent than 23%. So who knows what to believe?