Technology could be making us slower and weaker, according to new research.
researchers say that after looking at leg bones of humans dating back to the beginning of agriculture in Central Europe, our bones show a decline in “mobility and loading,” especially among males.
“These developments are likely to have brought about changes in divisions of labor by sex and socioeconomic organization as men and women began to specialize in certain tasks and activities – such as metal working, pottery, crop production, tending and rearing livestock,” said Alison Macintosh, of Cambridge University’s Department of Archaeology and Anthropology, who led the study.
Macintosh concluded that the mobility of early farmers--7,300 years ago--was about at the level of today’s student cross-country runners.
In just over 3,000 years mobility was reduced to the “level of those students rated as sedentary.”
Over time, our leg bones changed due to less intense activity.
“Both sexes exhibited a decline in anteroposterior, or front-to-back, strengthening of the femur and tibia through time, while the ability of male tibiae to resist bending, twisting, and compression declined as well,” said Macintosh.
She added that as humans transitioned to agriculture in Central Europe, the need to for long distance travel and heavy physical work diminished.
“As people began to specialize in tasks other than just farming and food production, such as metalworking, fewer people were regularly doing tasks that were very strenuous on their legs," she said.
Women’s leg bones did show some evidence of declining mobility, Macintosh said, but the “trends were inconsistent.”
She thinks the variation may be due to women having been more multitaskers. She said there was evidence in two of the oldest female skeletons of them having used their teeth to carry out tasks, which meant they may have not done jobs requiring stronger leg bones.
“This variability in the sexual division of labor in living agro-pastoralist groups shows the importance of context, ecology, and various cultural factors on sex differences in physical activity. So it is important when studying long-term trends in behavioral change between the sexes that the geographic region is kept small, to help control for some of this variability,” said Macintosh.
According to Macintosh, bones are “remarkably plastic and respond surprisingly quickly to change.”
When they are under stress such as long walks or runs, bones become stronger “as the fibers are added or redistributed according to where strains are highest.” This has been shown through the study of the skeletons of modern athletes, according to the study.
“Long-term biomechanical analyses of bones following the transition to farming in Central Europe hadn’t been carried out,” Macintosh said in a statement. “But elsewhere in the world they show regional variability in trends. Sometimes mobility increases, sometimes it declines, depending on culture and environmental context.”
“After the transition to farming, cultural change was prolonged and its pace was rapid, she added. “My research in Central Europe explores whether – and how – this long term pressure continued to drive adaptation in bones.”
Macintosh tracked the changes in bone structure over time by laser scanning skeletons found in cemeteries in Central Europe. The oldest dated from 5,300 BC and the most recent from 850 AD.
“I’m interested in how the skeleton adapted to people's specific behaviors during life, and how this adaptation can be used to reconstruct long-term changes in behavior and mobility patterns with cultural diversification, technological innovation, and increasingly more complex and stratified societies since the advent of farming,” she said.
In Central Europe, the technology and increased specialization had a major impact on our leg strength.
“As more and more people began doing a wider variety of crafts and behaviors, fewer people needed to be highly mobile, and with technological innovation, physically strenuous tasks were likely made easier,” said Macintosh. “The overall result is a reduction in mobility of the population as a whole, accompanied by a reduction in the strength of the lower limb bones."
Her findings were presented earlier this month at the Annual Meeting of the American Association of Physical Anthropologists in Calgary, Canada.