Scientists admit they really have no idea what 75% of human genetic code is actually used for
A new study has found that three-fourths of the human genome is non-functional or “junk DNA,” which might mean it doesn’t do anything … or it could just mean that scientists have no idea what it is used for yet. They do know, however, what it doesn’t do: These garbled sequences of nucleotides do not encode the proteins responsible for our bodies’ chemical reactions.
In the 1950s, it was widely assumed that most DNA coded for proteins, but over the years it has become clear that only a portion of a genome is responsible for encoding functional proteins. The term “junk DNA” was first used in 1972 to refer to DNA that has no known function.
University of Houston researchers, led by Dan Graur, used mathematical calculations to determine that only somewhere between 10 and 25 percent of our DNA is functional. They made their calculations using the deleterious mutation rate, which is the rate of harmful mutations, along with the replacement fertility rate. The study was published in Genome Biology and Evolution.
This is in contrast to the ENCODE study of 2012, which claimed that as much as 80 percent of our DNA was functional. That study garnered some criticism for its broad definition of the term “functional.” For Graur’s purposes, DNA that is functional is the part that has evolved to have important evolutionary effects and has a function that is maintained through natural selection.
Graur does not believe the claims of the ENCODE study and dismissed it by saying, “They had spent $400 million, they wanted something big to say.”
Graur believes that a setup with a lower percentage of functional DNA is actually better for humankind’s evolutionary prospects because it exposes less DNA to the risk of mutation, which boosts one’s chances of early death. The non-functional DNA cannot be affected by mutations because it can neither be improved nor damaged.