Q: ‘Is our DNA changing over time?’

I have been informed that towards the end of this year our DNA is changing. Is this scientifically possible?

Asked by Elaine Ford

The Long Awaited by KayVee.INC, on FlickrOur DNA is always changing – though usually only very slowly. If DNA didn’t change, then evolution wouldn’t be possible. David Attenborough wouldn’t be able to wow us with footage of a spectacular array of wildlife – and all humans would be identical.

DNA changes from generation to generation: when egg and sperm collide, DNA is mixed in new, previously-unseen combinations – and that’s why even brothers and sisters aren’t identical (unless you’re an identical twin, of course).

Change can be good – and bad

But sometimes DNA changes even within a single generation. One of the reasons we’re encouraged to wear sunscreen in intense summer sunlight is that the ultraviolet rays it contains can introduce errors into our DNA. Our DNA contains the instructions that make us, us. So if our DNA is damaged, things can go wrong: if the DNA in our skin cells is damaged by the UV rays in sunlight, we face an increased risk of developing a skin tumour.

Changes happen in other other ways, too. The human body is a mass of continually-dividing cells – and each time a cell divides it must copy its DNA. This copying process isn’t perfect: every time it happens, there’s a chance of an error creeping in. This is one of the reasons why the risk of disease – particularly diseases like cancer, which are typically caused by gene mutations – increases as we get older: there’s been more time for errors to creep in. There may only be one error here, and one error there – but they can gradually stack up…

Damage caused by things like UV rays in sunlight affect our DNA by changing the order of building blocks that it’s made from. The information ‘stored’ in our DNA can be influenced not only by the order of these building blocks, however, but also by chemical ‘tags’ that are attached to them. These ‘tags’ can determine whether the DNA can be ‘read’ or not. And the distribution of these tags can also change with time in response to our environment – our diet, for example.

So, it’s scientifically possible for DNA to change, for sure. (Though our bodies are actually designed to spot any changes made in error – the kinds of change that come about from UV ray damage, for example. (Our cells have cunning error-checking systems that constantly monitor our DNA for signs that things aren’t as they should be.))

But can our DNA suddenly change on a certain date – on the turning of a calendar from one month to the next? That kind of change certainly isn’t scientifically possible.

Answered by Jon Crowe (Molecular Guru)

Article by Jon Crowe

January 8, 2013

Jon Crowe is a science publisher (by day) and science writer (at various other times). A biochemistry graduate (University of Warwick, 1997), he was a runner-up in the 2001 Daily Telegraph/BASF Young Science Writer Competition (back when he was still classed as being young). Jon has co-authored two editions of Chemistry for the Biosciences, which first published in 2006, and is currently embroiled in writing the third. He lives with his fiancee, Katy, and their slightly rotund cat, Basil, in Eynsham, Oxfordshire (the location of one of the two toll bridges across the River Thames). They mostly enjoy drinking tea and eating cake. You can follow him on Twitter @crowe_jon

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