Explanation:
Why are homologous structures of the bones evidence of evolutionary relationships?
Ans.
Because they are predicted by the theory of evolution and the theroy of universal common ancestry.
Evidence is contextual, it requires some theory/hypothesis that predicts the existence of some specific fact in order for those facts to be evidence for that theory/hypothesis.
Evidence is only evidence if it is capable of excluding alternative explanations in favour of some explanation.
Whenever we find a new fossil species that we have never found before, then in order for the theory of ouniversal common ancestry through evolution to be correct, the bones must fit in some specific place in the phylogeny of life (the “tree of life”). If it does, then it is evidence for the theory, since the theory predicted it.
If we would find a fossil species that could only be explained as a mix between a bird and a mammal, or a dolphin and a squid, then this goes against the predictions of the science, as such a thing cannot have evolved according to our understanding of the tree of life.
Why you do have human bones? Because you inherited them from your parents, right? Because DNA copies itself.
So if two different species have the same bones, or the same DNA, it means they copied it from the same ancestor. The range of possibilities of how a DNA could be makes it effectively impossible that two sets of DNA could coincidentally have the same sequence. If two species have largely the same DNA, then ther emsut be an explanation for that. And you cannot completley separate bones from DNA, since the bones are an expression of the DNA.
