Processed pseudogenes: the 'fossilized footprints' of past gene expression

Though modern technology has allowed the access and sequencing of ancient DNA, evolutionary geneticists would like to access ancient ancestral organisms' transcriptomes in order to investigate more into the evolution of gene expression. Because of the fragility of mRNA and therefore near impossibility of ancient extraction, researchers want to use pseudogenes, which are non-functioning relatives of existing genes that no longer code for proteins. Each expressed gene purportedly has a certain number of "pseudogene offspring", and so researchers believe that these genes can be used as "fossilized footprints" of former gene expression. This process is not wholly accurate, and researchers stress the usefulness of extracting ancient transcriptome information for future studies of evolution.