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Wednesday, November 29, 2017

Where All the Women Are Strong: Bone Strength Comparison

     A new study comparing the bones of central European women who lived during the first 6,000 years of farming with those of modern athletes has shown that the average prehistoric agricultural woman had stronger upper arms than living female rowing champions.




     Researchers from the University of Cambridge's Department of Archeology say this physical prowess was likely obtained through tilling soil and harvesting crops by hand, as well as the grinding of grain for as much as five hours a day to make flour.





      Until now, archeological investigations of past behavior have interpreted women's bones solely through direct comparison to those of men. However, male bones respond to strain in a more visibly dramatic way than female bones.



     The Cambridge scientists say this has resulted in the systematic underestimation of the nature and scale of the physical demands borne by women in prehistory.




     "This is the first study to actually compare prehistoric female bones to those of living women," said Dr. Alison Macintosh, lead author of the study published this month in the journal Science Advances.




     "By interpreting women's bones in a female-specific context we can start to see how intensive, variable and laborious their behaviors were, hinting at a hidden history of women's work over thousands of years."



     The study used a small CT scanner in Cambridge's laboratory to analyze the arm (humerus) and leg (tibia) bones of living women who engage in a range of physical activity: from runners, rowers and footballers to those with more sedentary lifestyles.




     The bone strengths of modern women were compared to those of women from early Neolithic agricultural eras through to farming communities of the Middle Ages.

     "We can forget that bone is a living tissue, one that responds to the rigours we put our bodies through. 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," said Dr. Macintosh.




      "By analyzing 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 labor our ancestors were performing in prehistory."

      Over three weeks during trial season, Macintosh scanned the limb bones of the Open- and Lightweight squads of the Cambridge University Women's Boat Club, who ended up winning this year's Boat Race and breaking the course record. These women, most in their early twenties, were training twice a day and rowing an average of 120 kilometers a week at the time.




      The Neolithic women analyzed in the study (from 7400-7000 years ago) had similar leg bone strength to modern rowers, but their arm bones were 11-16% stronger for their size than the rowers, and almost 30% stronger than typical Cambridge students. {Bone scan is at left, above, vs. x-ray to the left}.




     The loading of the upper limbs was even more dominant in the study's Bronze Age women (from 4300-3500 years ago), who had 9-13% stronger arm bones than the rowers but 12% weaker leg bones.

     A possible explanation for this fierce arm strength is the grinding of grain. "We can't say specifically what behaviors were causing the bone loading we found. However, a major activity in early agriculture was converting grain into flour, and this was likely performed by women," said Dr. Macintosh.




      "For millennia, grain would have been ground by hand between two large stones called a saddle quern. In the few remaining societies that still use saddle querns, women grind grain for up to five hours a day." {The mano and metate is a variety of saddle quern used for nixtamalization or grinding.}

     "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."




     However, Macintosh suspects that women's labor was hardly likely to have been limited to this one behavior.

     "Prior to the invention of the plough, subsistence farming involved manually planting, tilling and harvesting all crops," said Dr. Macintosh. "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.

     "The variation in bone loading found in prehistoric women suggests that a wide range of behaviours were occurring during early agriculture. In fact, we believe it may be the wide variety of women's work that in part makes it so difficult to identify signatures of any one specific behavior from their bones."




     Dr. Jay Stock, senior study author added: "Our findings suggest that for thousands of years, the rigorous manual labor of women was a crucial driver of early farming economies. The research demonstrates what we can learn about the human past through better understanding of human variation today."

Where all the women are strong,
Steph (former member of Smith College Crew)

32 comments:

  1. Timely title, Steph! Given the current aesthetic appeal of a pair of large-caliber "guns", should we expect Soul Mills to be replacing Soul Cycles? Will "pumping cereal" replace "pumping iron"?

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  2. At the risk of going out on a limb, I wonder if there is a genetic component to this also?

    In the more recent past - certainly 500 years, perhaps longer - women's roles have changed, particularly in more industrial societies. Physical labor has become less necessary for survival, and the perception of "ideal" has changed towards a smaller frame - even the Rubenesque women were heavy, but not muscular.

    In earlier times big-boned women would have been seen as more attractive, and thus more likely to mate, leading to a genetic pool of larger bones. And the mating pool can change very quickly, as evidenced by the mustached women of Baleni-Sirbi.

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  3. I was surprised that Bronze Age women had 12% weaker leg bones than rowers. I know that rowers use their legs and cross-train, too, but everywhere Bronze Age women went, they got there by walking. Or was labor so specialized that millers just sat there all day and milled, while water fetchers fetched water, baby schleppers schlepped babies, etc? Doesn't seem intuitive. (Of course, these are just third-place Bronze Age people we're talking about. Probably Silver and Gold Age women had stronger leg bones...)

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    1. jan, that surprised me, too.

      "Silver and Gold Age" ;-)

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    2. Having avoided biology classes since 8th grade, I'd venture normal walking doesn't put that much strain on the leg bones, even when carrying wood/ water/ babies.

      But rowing seems like a lot of strain, much like doing leg presses, much more than body weight. I'll defer to Jan on the musculo-skeletal implications and Steph on the reality of getting into rows on a regular basis.

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    3. The fall I rowed was the most exhausting, beautiful, early morning experience on the Connecticut River. It takes much more leg strength than swimming or walking. But, if you are walking all the time. . .

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    4. Of course they wouldn't be walking all the time, I recall reading that neolithic people averaged about 10 miles per day - not sure where I read that.

      I would contend that walking puts very limited strain on the leg muscles and bones; rowing is like doing squats with weights. I suspect 30 minutes of rowing would leave my muscles more sore than a 10+ mile hike - though I've only done the latter recently.

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    5. Yet, walking (awl the time ;-)) is more weight bearing than rowing. Walking puts more downward force on your leg bones.

      Found this rowing study with quite interesting embedded video clips

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    6. I'm way out of my league even thinking about this, but I note that long distance runners (and Olympic speed walkers, which is a silly sport) are generally lean, and I assume this applies to their bone structures too.

      Some have noted that while men can readily out-sprint women, the two genders aren't so different in long distance running, a definite evolutionary advantage for early people following their dinners. Sweating is a big help too.

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  4. If you've rowed as part of an eight, you'll get this seat profiling . And you can always guess where I sat ;-). Hint, I was not cox or stroke.

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  5. Replies
    1. Thank g*d Fred and Barney didn't have them in an omelet!

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    2. What a find! Hundreds of eggs! Thanks for sharing the article, jan.

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  6. You know how, when you're skimming news stories while you're half asleep, you sometimes misread headlines in a way that makes them more interesting? So, instead of "Woman With Transplanted Uterus Gives Birth", I read "Woman With Transparent Uterus Gives Birth", and in the instant before I re-parsed it correctly, I thought, "Hey, I had that kit when I was a kid!"

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    1. And not "Me two", unless you're saying you were the cheerleader, rowing behind the bowwoman. (See above.) (Careful about revelatory cross-posting here!)

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  7. Explosive news from a galaxy far, far, away. Personally I think the rebels destroyed the Death Star.

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    1. That toddlering town. . .Quite cool stuff, eco.

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  8. Replies
    1. Wow, that's significant.

      Hafnium surprised me.

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    2. To me, the surprising thing about hafnium is that it's named for Copenhagen.

      I've found the dwindling supply of helium disturbing for a long time.

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  9. New post on "Something to Crow About: Happy Hooking, a Relatively New Tool Skill" is now up.

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