The persistence of pseudogenes [over 70-80 million years] is in itself evidence for their activity. This is a serious problem for evolution, as it is expected that natural selection would remove this type of DNA if it were useless, since DNA manufactured by the cell is energetically costly. Because of the lack of selective pressure on this neutral DNA, one would expect that old pseudogenes would be scrambled beyond recognition as a result of accumulated random mutations. Moreover, a removal mechanism for neutral DNA is now known.6
Given this, it is not known if all of what are currently thought of as pseudogenes have absolutely no function. In fact, some pseudogenes are believed to function as sources of information for producing genetic diversity. It is thought that partial pseudogenes are copied into functional genes during genetic recombination, producing variants of the functional gene. This phenomenon has been reported many times to include immunoglobulins of mice and birds, mouse histone genes, horse globin genes, and human beta globin genes. It is not known if this could be a possible role for the eta globin gene as well. However, the fact that the eta globin pseudogene is located between the fetal and adult genes suggests that it could play a role in gene switching
and there seems to be some preliminary evidence to this effect although the eta gene sequences part in this is still unknown.