Slashdot Mirror
Scientists Say the Future Looks Bleak For Our Bones
HughPickens.com writes Nicholas St. Fluer reports at The Atlantic that according to researchers, our convenient, sedentary way of life is making our bones weak foretelling a future with increasing fractures, breaks, and osteoporosis. For thousands of years, hunter-gatherers trekked on strenuous ventures for food with dense skeletons supporting their movements and a new study pinpoints the origin of weaker bones at the beginning of the Holocene epoch roughly 12,000 years ago, when humans began adopting agriculture. "Modern human skeletons have shifted quite recently towards lighter—more fragile, if you like—bodies. It started when we adopted agriculture. Our diets changed. Our levels of activity changed," says Habiba Chirchir. A second study attributes joint bone weakness to different levels of physical activity in ancient human societies, also related to hunting versus farming.
The team scanned circular cross-sections of seven bones in the upper and lower limb joints in chimpanzees, Bornean orangutans and baboons. They also scanned the same bones in modern and early modern humans as well as Neanderthals, Paranthropus robustus, Australopithecus africanus and other Australopithecines. They then measured the amount of white bone in the scans against the total area to find the trabecular bone density. Crunching the numbers confirmed their visual suspicions. Modern humans had 50 to 75 percent less dense trabecular bone than chimpanzees, and some hominins had bones that were twice as dense compared to those in modern humans. Both studies have implications for modern human health and the importance of physical activity to bone strength. "The lightly-built skeleton of modern humans has a direct and important impact on bone strength and stiffness," says Tim Ryan. That's because lightness can translate to weakness—more broken bones and a higher incidence of osteoporosis and age-related bone loss. The researchers warn that with the deskbound lives that many people lead today, our bones may have become even more brittle than ever before. "We are not challenging our bones with enough loading," says Colin Shaw, "predisposing us to have weaker bones so that, as we age, situations arise where bones are breaking when, previously, they would not have."
The team scanned circular cross-sections of seven bones in the upper and lower limb joints in chimpanzees, Bornean orangutans and baboons. They also scanned the same bones in modern and early modern humans as well as Neanderthals, Paranthropus robustus, Australopithecus africanus and other Australopithecines. They then measured the amount of white bone in the scans against the total area to find the trabecular bone density. Crunching the numbers confirmed their visual suspicions. Modern humans had 50 to 75 percent less dense trabecular bone than chimpanzees, and some hominins had bones that were twice as dense compared to those in modern humans. Both studies have implications for modern human health and the importance of physical activity to bone strength. "The lightly-built skeleton of modern humans has a direct and important impact on bone strength and stiffness," says Tim Ryan. That's because lightness can translate to weakness—more broken bones and a higher incidence of osteoporosis and age-related bone loss. The researchers warn that with the deskbound lives that many people lead today, our bones may have become even more brittle than ever before. "We are not challenging our bones with enough loading," says Colin Shaw, "predisposing us to have weaker bones so that, as we age, situations arise where bones are breaking when, previously, they would not have."
Humans regularly lived to their 50s and 60s as far back as the paleolithic. Average life expectancy numbers are misleading because the high rate of infant mortality and death during childhood. A hunter-gatherer who can survive long enough to be a teenager is quite likely to live to old age, but it's getting that far that's the tricky part.
That is not how averages work. Yes, the average age was 20-30 years but that includes lots of children, newborns, and possibly war deaths (depending on which statistics you are looking at). Generally speaking if you lived to puberty then you had a reasonable chance to hit 60+ just like modern humans.
Also consider the introduction and increasing consumption of alcohol. It has significant calcium reducing properties.
Modern human skeletons have shifted quite recently towards lighter—more fragile, if you like—bodies.
Sweet! Maybe we will also start evolving wings and finally be able to fly without manufactured air foils! I for one intend to sit on the couch more and make this happen faster!
If humans could fly, we'd consider it exercise and never do it.
-- origin unknown
If it weren't for deadlines, nothing would be late.
Yeah, because being a farmer is such a cushy gig.
Modern farm tractors are equipped with air-conditioned cabs and stereo systems -- Farming (in the first world) is a lot cushier than it used to be!
Bull. The Bible itself tells us the full span of a man's years is "threescore and ten". That's from the Book of Psalms, and was probably written around 700 BC.
Not that I agree with the GP's 20-30 numbers, but I think he refers to humans who lived tens of thousands of years ago, not in relatively recent biblical times. You deleted his point that humans who lived more recently (which I parse to mean starting around biblical times) lived up to 70-100 years. I think those larger numbers are likely true of earlier humans too, but the premature mortality of those times cuts the average down.
If it weren't for deadlines, nothing would be late.