8.2 percent of our DNA is functional

Only 8.2% of human DNA is likely to be doing something important – is 'functional' – say Oxford University researchers.

This figure is very different from one given in 2012, when some scientists involved in the ENCODE (Encyclopedia of DNA Elements) project stated that 80% of our genome has some biochemical function.

That claim has been controversial, with many in the field arguing that the biochemical definition of 'function' was too broad – that just because an activity on DNA occurs, it does not necessarily have a consequence; for functionality you need to demonstrate that an activity matters.

To reach their figure, the Oxford University group took advantage of the ability of evolution to discern which activities matter and which do not. They identified how much of our genome has avoided accumulating changes over 100 million years of mammalian evolution – a clear indication that this DNA matters, it has some important function that needs to be retained.

'This is in large part a matter of different definitions of what is "functional" DNA,' says joint senior author Professor Chris Pointing of the MRC Functional Genomics Unit at Oxford University. 'We don't think our figure is actually too different from what you would get looking at ENCODE's bank of data using the same definition for functional DNA.