More than 90 per cent of human DNA is doing nothing very useful, and large stretches may be no more than biological baggage that has built up over years of evolution, Oxford researchers claim.
The scientists arrived at the figure after comparing the human genome with the genetic makeup of other mammals, from dogs and mice to rhinos and horses.
The researchers looked for sections of DNA that humans shared with the other animals, which split from our lineage at different points in history. When DNA is shared and conserved across species, it suggests that it does something valuable.
Gerton Lunter, a senior scientist on the team, said that, based on the comparisons, 8.2 per cent of human DNA was “functional,” meaning that it played an important enough role to be conserved by evolution.
“Scientifically speaking, we have no evidence that 92 per cent of our genome is contributing to our biology at all,” Lunter said.
Researchers have known for some time that only 1 per cent of human DNA is held in genes that are used to make crucial proteins to keep cells — and bodies — alive and healthy. The latest study, reported in the journal Plos Genetics, suggests that a further 7 per cent of human DNA is equally vital, regulating where, when, and how genes are expressed.
But if much of our DNA is so worthless, why do we still carry it around? “It’s not true that nature is parsimonious in terms of needing a small genome. Wheat has a much larger genome than we do,” Lunter said. “We haven’t been designed. We’ve evolved, and that’s a messy process. This other DNA really is just filler. It’s not garbage. It might come in useful one day. But it’s not a burden.
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