Bone Density Drop in Modern Humans Linked to Less Physical Activity

Dec 25, 2014

Image courtesy of © AMNH/J. Steffey and Brian Richmond

By Charles Q. Choi

The relatively lightly built skeletons of modern humans developed late in evolutionary history, and may have been the result of a shift away from a nomadic lifestyle to a more settled one, according to a new study.

These findings may shed light on modern bone conditions such as osteoporosis, the scientists said.

Bone is one of the strongest materials found in nature. Ounce for ounce, bone is stronger than steel, since a bar of steel of comparable size would weigh four or five times as much. In another comparison, a cubic inch of bone can in principle bear a load of 19,000 lbs. (8,620 kilograms) or more — roughly the weight of five standard pickup trucks — making it about four times as strong as concrete.

Still, modern humans have a relatively lightly built skeleton compared with those of chimpanzees — the closest living relatives of humans — as well with those of extinct human lineages.

“Throughout our skeleton, our joints are about three-quarters to one-half as dense as those of our early human ancestors and those of other modern primate species,” study co-author Brian Richmond, curator of human origins at the American Museum of Natural History in New York City, told Live Science. “That raises the question of when this happened in humans.”


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5 comments on “Bone Density Drop in Modern Humans Linked to Less Physical Activity

  • What about the numerous studies that show skeletal gracilisation in mammals is an indirect consequence of the selection for docile behaviour? Couldn’t this also apply to selection for docile behaviour in humans clustering together in ever more densely packed societies?

    As an aside, I doubt that any human could ever approach the strength of a male oran-utan. It’s about the quality of the muscles tissue, leverage and design of the skeleton.

    see : ‘Intertwined evolution of human brain and brawn’ http://www.sciencedaily.com/releases/2014/05/140527185347.htm



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  • This reminds me of a discussion, recorded on YouTube somewhere, by Tim Noakes from South Africa. About the extraordinary international athletics successes of people from a West African ethnic origin. Possibly owing to South Africa having recently emerged from ‘real’ racism it may be possible for South African researchers to undertake studies that might otherwise be declined of undiscussable for fear of political incorrectness in nations which merely play at being racist.

    Outcome of their research is that many of the African long distance runners, although typically much lighter, leaner, and smaller, have much stronger muscles and so can produce more energy over a longer period without incurring damage that unconsciously affect fatigue emotions which govern and constrain performance.

    Theory being that this is an adaptation associated with persistence hunting over a very wide foraging range in relatively hot environmental conditions. Body mass, power, and endurance being optimised which avoids dragging around excess body mass when scavenging and hunting. Also leaness which optimises thermal regulation.

    There’s some discussion about osteoporosis on YouTube presentations at various Ancestral Health Society symposiums. Implications for people at risk of osteoporosis is to eliminate dietary starch and sugars. And also counter-intuitively to avoid calcium supplements, which apparently aggravates loss of calcium from bone. The issue being that osteoporosis is rarely a consequence of impaired calcium uptake or the lack of available calcium from food sources. If most osteoporosis is a consequence of grain starches and insufficient exertion then then the easy fix is less starch more dietary fat and more exercise.

    Osteoporosis may be yet another aspect of the same root cause of the NCD epidemic that’s emerged only recently over the last 30 years, possibly for similar reasons as to how most people were urged to take up smoking in the early to mid 20th century.



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  • Pete H Dec 27, 2014 at 6:08 pm

    Outcome of their research is that many of the African long distance runners, although typically much lighter, leaner, and smaller, have much stronger muscles and so can produce more energy over a longer period without incurring damage that unconsciously affect fatigue emotions which govern and constrain performance.

    Interestingly, European fell-racers have a similar build, with stronger but smaller muscles, with a well tuned circulatory system in support.



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  • Stafford Gordon Dec 31, 2014 at 1:04 pm

    Bone density is proportionate to physical activity; well well, who would have thought that.

    . . . . . and gravitational loading – as space travellers find out on their return!



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