Final answer:
The method used to estimate the ancestral history of protein or nucleic acid sequences is called cladistics, involving the creation of phylogenetic trees.
Step-by-step explanation:
The method you’re referring to for estimating the ancestral history of a set of protein or nucleic acid sequences is called cladistics. This approach involves the creation of phylogenetic trees or cladograms, which are branching diagrams that illustrate the evolutionary relationships between species. At each step in cladistics, the taxa that are separated by the smallest distance — indicative of the closest genetic relationship — are combined. The evolutionary history is inferred by analyzing the amino acid or nucleotide sequence homology and utilizing various calculations to determine the level of similarity, which in turn reflects the distance or time since they diverged from a common ancestor.
Advanced bioinformatics tools and databases such as GenBank support this process, providing data that scientists use to align and analyze sequences. By comparing the sequences of interest to a database, one can estimate evolutionary distances, which helps in constructing the phylogenetic trees. Such molecular analysis has significantly improved our understanding of evolutionary kinship and the lineage of different species, often confirming or refining the results obtained from traditional morphological studies.