Anthropologist Prof Dean Snow from Pennsylvania State University analyzing ochre-stenciled handprints in Paleolithic caves in France and Spain has determined that about 75 percent of the handprints were left by women.

The assumption has been that handprints, whether stencils – paint blown around the hand – or actual paint-dipped prints, were produced by men because other images on cave walls were often hunting scenes. The smaller handprints were assumed to be adolescent boys.

Prof Snow came across the work of Liverpool University scientist Dr John Manning, who about 10 years ago tried to use the relationships of various hand measurements to determine not only sex, but such things as sexual preference or susceptibility to heart disease. Prof Snow wondered if he could apply this method to the handprints left in cave sites in Europe.

“Manning probably went way beyond what the data could infer, but the basic observation that men and women have differing finger ratios was interesting. I thought here was a neat little one off science problem that can be solved by applications of archaeological science,” Prof Snow explained.

Prof Snow visited a number of European caves, including the famous El Castillo cave in Spain, and collected existing cave art images with size indications. He also collected hand images from people with European and Mediterranean ancestry.

The scientist found he needed a two-step process for the modern hands to successfully differentiate men from women. He first measured the overall size of the hand using five different measurements. This separated the adult male hands from the rest. He found that step one was 79 percent successful in determining sex, but adolescent males were classified as female.

Step two compares the ratios of the index finger to the ring finger and the index finger to the pinky to distinguish between adolescent males and females. For the known hands, the success rate, though statistically significant, was only 60 percent. There is too much overlap between males and females in modern populations.

“I thought the fact that we had so much overlap in the modern world would make it impossible to determine the sex of the ancient handprints. But, old hands all fall at or beyond the extremes of the modern populations. Sexual dimorphism was greater then than it is now,” Prof Snow said.

Sexual dimorphism implies that males and females differ. Not only were male hands larger, the scientist found that development of the fingers, how long they are relative each other, also differs significantly.

The first step in the process showed that only 10 percent of the handprints on cave walls in Spain and France were left by adult males.

The second step indicates that 15 percent were placed by adolescent males, leaving 75 percent of the handprints female. The findings appear in a paper published in the journal American Antiquity.

“By just eyeballing, I’m more accurate with the modern hands than the formulas I developed. There are some variables there that I’m not aware of yet. The algorithms are pretty good, but they could be better,” Prof Snow said.

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Bibliographic information: Dean R. Snow. 2013. Sexual Dimorphism in European Upper Paleolithic Cave Art. American Antiquity, vol. 78, no. 4; doi: 10.7183/0002-7316.78.4.746