 Over time, it is also common for duplicated copies of genes to accumulate mutations and become inactive pseudogenes.In many cases, these events can be inferred only through comparing sequenced genomes.Examples of unexpected but recently confirmed ancient genome duplications include baker's yeast ("Saccharomyces cerevisiae"), mustard weed/thale cress ("Arabidopsis thaliana"), rice ("Oryza sativa"), and an early evolutionary ancestor of the vertebrates (which includes the human lineage) and another near the origin of the teleost fishes.