Farming is the reason our bones are much weaker than our hunter-gatherer ancestors’

The human skeleton has become lighter and more fragile since the invention of agriculture. In a recent study published in the Proceedings of the National Academy of Science (PNAS) researchers claim that the shift from foraging to farming and the consequent adoption of more sedentary lifestyles account for our bone structure being substantially weaker than that of our hunter-gatherer ancestors.

Comparison between hunter-gatherers’ and farmers’ bone mass (credit: Timothy Ryan)

Comparison between hunter-gatherers’ and farmers’ bone mass (credit: Timothy Ryan)

The study shows that, while human hunter-gatherers from around 7,000 years ago had bones comparable in strength to modern orangutans, farmers from the same area but over 6,000 years later had significantly lighter and weaker bones. Specifically, the bone mass difference was around 20% in favour of the foragers – which curiously enough is roughly what astronauts lose after three months of weightlessness in space. The team of researchers ruled out diet differences and changes in body size as possible causes and ascribed the degradation in human bone strength to the significant reduction, over the millennia, of physical activity.

These results are somewhat worrisome as our modern lifestyle is dangerously more sedentary than ever before. On the flip side of the coin however, the study suggests that more exercise could be the key to stronger and healthier bones and that an active lifestyle could significantly reduce the risk of fracture and the insurgence of osteoporosis, particularly in our later years. As a matter of fact, there is no anatomical reason why a person born today could not achieve the same body strength of an early human forager or even an orangutan – although even extremely active people are unlikely to experience intense and frequent enough bone stress to allow for the increased bone strength seen in the hunter-gatherers and non-human primate bones. “The fact is, we’re human, we can be as strong as an orangutan – we’re just not, because we are not challenging our bones with enough loading, predisposing us to have weaker bones so that, as we age, situations arise where bones are breaking when, previously, they would not have” – co-author Dr Colin Shaw from the University of Cambridge’s Phenotypic Adaptability said. Shaw also points out that while the 7,000-year-old foragers had vastly stronger bones than the 700-year-old farmers, neither competes with even earlier hominids from around 150,000 years ago: “Something is going on in the distant past to create bone strength that outguns anything in the last 10,000 years”.

Even if the study concerns humans dating back millennia there is certainly a valuable lesson that we can all benefit from. “You can absolutely morph even your bones so that they deal with stress and strain more effectively. Hip fractures, for example, don’t have to happen simply because you get older if you build your bone strength up earlier in life, so that as you age it never drops below that level where fractures can easily occur” – Shaw concludes.

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Carlo Bradac

Carlo Bradac

Dr Carlo Bradac is a Research Fellow at the University of Technology, Sydney (UTS). He studied physics and engineering at the Polytechnic of Milan (Italy) where he achieved his Bachelor of Science (2004) and Master of Science (2006) in Engineering for Physics and Mathematics. During his employment experience, he worked as Application Engineer and Process Automation & Control Engineer. In 2012 he completed his PhD in Physics at Macquarie University, Sydney (Australia). He worked as a Postdoctoral Research Fellow at Sydney University and Macquarie University, before moving to UTS upon receiving the Chancellor Postdoctoral Research and DECRA Fellowships.

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