Ancient Humans Were Mostly Right-Handed, Too   Live Science - April 30, 2011
Humanity's right-hand dominance might be more than 500,000 years old, new research indicates. The trait of right-handedness is commonly believed to be a sign of the development of another uniquely human trait -- language.

Left-handedness common in Ice Age   BBC - February 13, 2004

The fraction of left-handed people today is about the same as it was during the Ice Age, according to data from prehistoric handprints. They were found in caves painted during the Upper Palaeolithic period, between 30,000 and 10,000 years ago. Left-handedness may have conferred prehistoric man advantages, such as in combat, say the researchers.