Why Our Ancient Hunter-Gatherer Ancestors Had Stronger Bones Than We Do

In the past, our ancestors' bones were far stronger than ours are today. Now, scientists have taken a closer look at the evolution of human bones and have found exactly why our skeletal structure has become more delicate over time.

About 7,000 years ago, human hunter-gatherers had bones comparable in strength to modern orangutans. In fact, bone mass was around 20 percent higher in foragers, which is the equivalent to what an average person would lose after three months of weightlessness in space.

Surprisingly, farmers from the same area over 6,000 years later had significantly lighter and weaker bones that would have been more susceptible to breaking. After ruling out diet differences and changes in body size as possible causes, the scientists found that reductions in physical activity are probably the root cause of degradation in human bone strength across millennia.

The findings actually support the idea that exercise rather than diet is key to preventing heightened fracture risk and conditions, such as osteoporosis, in later life. Higher exercise in early life results in a higher peak of bone strength around the age of 30, meaning that bone weakening with age is less detrimental.

"Contemporary humans live in a cultural and technological milieu incompatible with our evolutionary adaptations," said Colin Shaw, one of the researchers, in a news release. "There's seven million years of hominid evolution geared toward action and physical activity for survival, but it's only in the last say 50 to 100 years that we've been so sedentary-dangerously so. Sitting in a care or in front of a desk is not what we have evolved to do."

That said, there's no reason why a person born today couldn't attain the same bone strength of an early human forager. However, even the most active people today are unlikely to be loading bones with enough frequent and intense stress to allow for the increased bone strength seen in traditional hunter-gatherers.

The findings are published in the journal Proceedings of the National Academy of Sciences.

Want to learn more? Check out the video below, courtesy of YouTube.

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