DNA is similar in species that share a common ancestor according to which field?

• A. Comparative Biochemistry
• B. Comparative Anatomy
• C. Molecular Genetics
• D. Paleontology

Answer: (A)

DNA similarity among species that share a common ancestor is studied by comparing the chemical makeup of organisms. Comparative biochemistry focuses on comparing molecules such as DNA, proteins, and enzymes across different species to infer evolutionary relationships. When two species have very similar DNA sequences, it indicates they inherited those sequences from a shared ancestor, and there hasn’t been enough time for them to diverge completely. This approach uses the chemical evidence of life to reconstruct how species are related. Other fields look at different kinds of evidence—comparative anatomy examines physical structures, paleontology uses fossils, and molecular genetics digs into gene function and inheritance on a more detailed level—but for evaluating DNA similarities as a signal of common descent, comparative biochemistry is the best fit.