How are these homologous structures evidence of an evolutionary relationship?

When Swedish botanist Carolus Linnaeus was formulating his system of taxonomy to name and categorize organisms in the 1700s, how the species looked was the determining factor of the group in which the species was placed. As time passed and technology advanced, homologous structures became more important in deciding the final placement on the phylogenetic tree of life.

Linnaeus's taxonomy system places species into broad categories. The major categories from general to specific are kingdom, phylum, class, order, family, genus, and species. As technology evolved, allowing scientists to study life at the genetic level, these categories have been updated to include domain, the broadest category in the taxonomic hierarchy. Organisms are grouped primarily according to differences in ribosomal RNA structure.

Explanation:

Si.

layer 3 is younger than layer 6.