A phylogenetic tree is a hypothetical reconstruction of lines of descent. Both creation and evolutionary biologists use phylogenetic trees, because both acknowledge at least some degree of change over time. However, while evolutionists believe that all life stems from a single common ancestor, creationists believe that life stems from a number of independent ancestors, involving separate phylogenetic trees -- a model known as baraminology.
It is difficult to reconstruct phylogenetic trees. Different approaches include:
- Morphology: Scientists often conclude species are related simply because they share physical characteristics. Thus, because they conclude that chimps are physically the most similar to humans, they conclude that the two species are most closely related. This is a logical fallacy, however. Morphological similarity is neither a necessary condition nor a sufficient condition of common descent;
- Analysis of genetic similarity: Organisms with similar DNA sequences are assumed to be closely related. However, studies have shown that convergent evolution can result in completely incorrect conclusions.
- Bull, J.J., Badgett, M.R., Wichman, H.A., Huelsenbeck, J.P., Hillis, D.M., Gulati, A., Ho, C., and Molineux, I.J. (1997) "Exceptional convergent evolution in a virus". Genetics 147: 1497-507.