Indonesia's Gua Ham cave, part of a Borneo mountainside complex, contains these and other hand stencils dating back some 10,000 years.
Red pigment was blown over hands to make the stencils. Left-hand stencils are more common than right-hand ones.
"Experiments have shown that right-handed people tend to make stencils of their left hands, because they use their right hands to hold the pigment tube or to help purse their lips to spray on the pigment," archaeologist Dean Snow explained.
Photograph by Carsten Peter, NGS Image Collection