Since I last wrote on this subject, I have had the time to reflect on the aspect of evolution, bone structure and why or why not animals could exhibit a metallic skeleton in a different time and space. So, here are my thoughts.
First off, there is a need to establish the differences that our bone structure has in comparison to an equivalent metallic structure, but purely in terms of strength of materials. The bones in our body have a 2% strain to failure, with a tensile strength of 150MPa. And the expert on this site says that its not that great for a structural material so I’ll take his word for it.
However, unlike metals, our bones aren’t exactly all solid but hollow to a certain point, and that’s really what lends them the lightness for being moved around. Imagine if they were as dense as some of those titanium implants.
Sure, they are said to be lighter than what was available earlier, but imagine if that was what your body’s skeletal system was made of, and then think of how mammoth an effort it would be just to carry yourself around.
But, the thing that I am more interested about is how a metallic skeleton would perform all of the other functions. For instance, where would the ability of growth arise from, not to forget the ability to heal in case of injuries (or dents if you had metal bones) to the bone.
While its true that our body can work with metals, the only one that’s of any significant value in terms of quantity is iron, given that it forms an integral part of the blood’s haemoglobin.
So, while there can be an argument made for the presence of metallic bones in animals, the course of evolution and therefore definition of entire biochemical processes shall have to be redefined for the concept to even make sense on an imaginative level.