Evolutionary biologists have always used a broad range of modern organisms to infer the characteristics that ancestral organisms may have possessed. Genomic sequences are now available for an increasing number of species, and scientists studying evolutionary processes can take advantage of this enormous amount of data to bring evolution into the arena of molecular studies. By aligning the sequences of homologous genes and looking for regions of similarity and where changes have occurred, it is possible to infer the sequence of the ancestral gene.

What term is used to describe the changes in gene sequence that have occurred?

How can we use what we know about this process to construct a timeline showing when various sequence changes occurred and when they lead to the modern sequences that we know today?