So, to summarize, we don't have a steel skeleton because 1. We evilved from the sea, where Calcium is far more abundant than metals 2. Having a skeleton 100x h

So, to summarize, we don't have a steel skeleton because 1. We evilved from the sea, where Calcium is far more abundant than metals 2. Having a skeleton 100x harder than out current one, would require 100x stronger muscles and tendons, if you don't want them to snap 3. You couldn't swim with metal bones, which would again be a problem with 1., and make it hard to survive as a species if you drown very easily. Other arguments, which however, were debunked 1. It takes too much energy to create steel. It doesn't, maybe twice as much. 2. You also have other bone functions. However, you could also have those with a semi-steel, semi-organic bone structure. 3. Bones need to decompose, so that you don't steal too much resources from the environment. Possible argument?