Why can comparisons of protein similarity between species can reveal the degree of genetic kinship?

The closer the protein structures are to those of another species, the more likely it is that there is a genetic relationship between them, if descent with modification is accurate and protein structures are passed down from one generation to the next.

While the protein structures of cytochrome c and other organisms show groups of related species all equally distant from each other, there was much excitement in the field when it came to examining the structures in order to determine evolutionary descent and relationships. ( Denton Evolution a theory is Crisis)

Another illustration is the protein structures of humans and pigs; pigs' heart values have been found to be the most similar to human protein structures. Thought to be the best sources of organ replacements for humans due to purported genetic kinships, apes and chimpanzees cause enormous rejections and are no longer used.

Comparisons of protein similarity between species can reveal the degree of genetic kinship because proteins are encoded by genes, and the sequences of these genes are inherited from common ancestors. As species evolve and diverge, changes occur in their DNA sequences, leading to differences in the amino acid sequences of their proteins. By comparing the similarity of protein sequences between different species, scientists can infer their genetic relatedness and evolutionary history.