You report that prehistoric hand stencils on cave walls with various digits missing could represent a sign language. I am a computer scientist, not a linguist, so I have a different take on the matter ...

The artists who spattered paint around their hands placed on cave walls 40,000 years ago can now be identified as either male or female. A new method borrows techniques from forensic science to find ...

No right hands are shown in the illustrations or photos in your story, leading me to believe all the cave stencils are of left hands. As a left-handed person, I wonder if any of the stencil-makers ...