>> But if you had metal bones they wouldn't ever need repairing: titanium alloy for example has a fatigue strength of about 500MPa which is more than five times greater than the stresses that it would experience in its life as a bone.
It's worth remembering that Calcium (the substance bones are made of) is, in fact, a metal [1]. And our bodies have no problem growing and repairing our bones. Why wouldn't that happen with steel?
Also- the bit about the stresses that a titanium alloy bone would experience in its lifetime- yeah, that, probably. We probably have bones as tough as they need to be, or _needed_ to be in the last million or so years.
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[1] A factoid that my 16 year-old self, obsessed with Metal (the music) found deeply satisfying. "Dude, my bones are made of METAL".
It's worth remembering that Calcium (the substance bones are made of) is, in fact, a metal [1]. And our bodies have no problem growing and repairing our bones. Why wouldn't that happen with steel?
Also- the bit about the stresses that a titanium alloy bone would experience in its lifetime- yeah, that, probably. We probably have bones as tough as they need to be, or _needed_ to be in the last million or so years.
________________
[1] A factoid that my 16 year-old self, obsessed with Metal (the music) found deeply satisfying. "Dude, my bones are made of METAL".