To characterize the contributions of individual amino acids to the structure ... necessary for this type of characterization, some researchers have adopted a 'directed evolution' approach that ...

That is, changes affect the "letters" (four different types ... structures that carry the genes). The changes and variations in genetic code that occur over time are referred to as "molecular ...

If evolution occurs through gradations, the critics say, how could it have created the separate parts of the eye -- the lens, the retina, the pupil, and so forth -- since none of these structures ...

Scientists found that evolution led bird and mammal brains to evolve separately, using different genetic instructions.