Vestigial Organs | Homologies | Embryology | Tree of Life

Overwhelming evidence shows us that all species are related—that is, that they are all descended from a common ancestor. One hundred and fifty years ago, Darwin saw evidence of these relationships in striking anatomical similarities between diverse species, both living and extinct. Today, we realize that most such resemblances—in both physical structure and embryonic development-are expressions of shared DNA, the direct outcome of a common ancestry.