Does Your Handprint Give Away Your Sex?

Cave paintings usually depict bison and other hunting equipment — so naturally, scientists once assumed that any handprints discovered near those paintings belonged to men, not women.

That assumption was challenged last October, when archaeologist Dean Snow of Pennsylvania State University analyzed 12,000- to 40,000-year-old hand stencils found in eight French and Spanish cave dwellings. By measuring the ratios of various finger spans in 111 people of European descent living near Penn State, Snow devised an algorithm that could predict the sex of a handprint, and he used that algorithm on 32 of the ancient hand stencils. The numbers held together about 60 percent of the time in modern hands (the other 40 percent possibly owing to the substantial overlap between modern male and female hands), but the results of the ancient handprint analysis were even more definitive: the data suggested that a majority of these primeval artists were female.

The shape and size of a handprint might give clues about the person's sex — but variations across time and space are uncertain.

Now, though, the research is proving more complicated than once thought. Here’s Virginia Hughes, writing for Only Human:

The new study, published Monday in the Journal of Archaeological Science, challenges Snow’s reference sample. A team led by Patrik Galeta of the University of West Bohemia in Sedláčkova, Czech Republic, collected handprints from 100 contemporary people in southern France and then ran those measurements through Snow’s algorithm.

Galeta found that Snow’s algorithm predicted female hands fairly well, but was useless for males, making it overall a bad predictor of sex. The study showed, in other words, that sex differences in hands seem to exist among modern people living in Pennsylvania, but not among modern people living in France. And if two modern populations don’t match, then how can we possibly say anything about handprints tens of thousands of years old?

That question is nothing short of unsettling for archaeologists, who rely on contemporary populations for comparison across thousands of years of data. But when even present-day data is inconsistent, how do they even begin to understand the discrepancies buried in years of evolutionary change?

The answer to that is itself unclear. Still, Snow defends his algorithm; he claims that it might be a question of computation — that the Czech researchers didn’t use employ his algorithm correctly, or that they measured hand length differently.

Regardless, Hughes writes that this debate speaks to the nature of uncertainty in archaeology. Any study of the past has built-in biases based on what we know of the present — and scientists must be careful about how they “work backwards” on modern-day premises.