Scientists have discovered mystery snippets of mammal DNA that have survived eons of evolution and yet have no apparent purpose. The finding reveals just how much we don’t know about the secrets hidden in our genome and that of other animals.
Most genes change throughout evolution via mutations; useless ones eventually get weeded out of the population while the helpful modifications take hold. However, about 500 regions of our DNA — the body’s instruction code made up of base pairs of molecules — have apparently remained intact throughout the history of mammalian evolution, or the past 80 million to 100 million years, basically free of mutations.
“Mutations are introduced into these regions just as they are everywhere else, but they’re swept out of the genome much more quickly,” said researcher Gill Bejerano, professor of developmental biology and computer science at Stanford University. “These regions seem to be under intense purifying selection — almost no mutations take hold permanently.”