Not surprising, but structurally interesting
Berkeley Lab materials scientists used x-rays to exam bones from 34 to 99-year old people, in order to see how aging affects bone structure and its ability to resist fracture:
“We found that biological aging increases non-enzymatic cross-linking between the collagen molecules, which suppresses plasticity at nanoscale dimensions, meaning that collagen fibrils can no longer slide with respect to one another as a way to absorb energy from an impact,” [Robert O.] Ritchie says.
“We also found that biological aging increases osteonal density, which limits the potency of crack-bridging mechanisms at micrometer scales.”
© 2011 Lynn Yaris, The Brittleness of Aging Bones – More than a Loss of Bone Mass: Berkeley Lab Researchers Show How Loss of Bone Quality Also a Major Factor, U.S. Department of Energy — Lawrence Berkeley National Laboratory [Berkeley Lab] (29 August 2011)
Elizabeth A. Zimmermann, Eric Schaible, Hrishikesh Bale, Holly D. Bartha, Simon Y. Tang, Peter Reichert, Bjoern Busse, Tamara Alliston, Joel W. Ager III, and Robert O. Ritchie, Age-related changes in the plasticity and toughness of human cortical bone at multiple length scales, Proceedings of the National Academy of Sciences [PNAS], doi: 10.1073/pnas.1107966108 (early online publication, 22 August 2011)
Overly optimistic “we can be young forever” advocates need to come to grips with biological complexity
Everything degrades, eventually.