The arm bones of women who lived 7,000 years ago show an incredible level of strength - even higher than today's elite athletes. That's according to a first-ever study comparing prehistoric bones to those of living people.
The finding suggests a revision of history - the everyday lives of prehistoric women were filled with hard manual labour, rather than just sitting at home doing lighter domestic tasks while the men slogged.
Prior to the advent of writing, there are no clear records describing how our ancient ancestors lived. We have some artefacts, and rock art, and bones - and, as it turns out, those bones can tell us a lot.
"It can be easy to forget that bone is a living tissue, one that responds to the rigours we put our bodies through," said lead author Alison Macintosh of the University of Cambridge's Department of Archaeology and Anthropology.
"Physical impact and muscle activity both put strain on bone, called loading. The bone reacts by changing in shape, curvature, thickness and density over time to accommodate repeated strain."
Previous studies only compared female bones to contemporary male bones, the researchers said - and that's a problem, because the response of male bones to stress and change is much more visibly dramatic than that of women.
For instance, as humans moved from a hunter-gatherer lifestyle constantly on the move to a more settled agrarian one, changes can be observed in the structure of the shinbone (or tibia) - and these changes were much more pronounced in men.
However, a comparison of the bones of prehistoric women to the bones of living female athletes can help us work out a more accurate picture of what those prehistoric women were doing.
"By analysing the bone characteristics of living people whose regular physical exertion is known, and comparing them to the characteristics of ancient bones, we can start to interpret the kinds of labour our ancestors were performing in prehistory," Macintosh said.
Macintosh's team recruited Cambridge athletes such as rowers and runners, as well as more sedentary volunteers, and used a small CT scanner to analyse their arm and leg bones.
They also used 3D laser imaging and silicone moulding to create models of 89 tibiae and 78 humeri of women from the Neolithic, the Bronze Age, the Iron Age and the Medieval.
What they found was that women's leg strength hasn't changed a great deal over the millennia - but powerful arms used to be the norm. Neolithic women, the researchers found, had arm strength 11-16 percent stronger than those of modern rowers, and 30 percent stronger than those of non-athletes.
Bronze Age women's arms were 9-13 percent stronger than those of rowers.
It's difficult to say what activities would have contributed to this increased strength, but we can make some educated hypotheses - such as grinding grain into flour by hand using stones, an activity that could have taken up to five hours a day.
"The repetitive arm action of grinding these stones together for hours may have loaded women's arm bones in a similar way to the laborious back-and-forth motion of rowing," Macintosh said.
And there were other tasks women would have been performing, too.
"Prior to the invention of the plough, subsistence farming involved manually planting, tilling and harvesting all crops. Women were also likely to have been fetching food and water for domestic livestock, processing milk and meat, and converting hides and wool into textiles."
So next time you see some sexist twerp wonking on about how prehistoric men did the work while women sat on their hands, feel free to scoff long and loud.
The research has been published in the journal Science Advances.