"The purpose of DNA is to provide a template for RNA which in turn provides the template for proteins, which is called the 'central dogma of molecular biology'."

That's the purpose of 4% of DNA, not THE purpose of DNA. The arrogance of calling the rest of it "junk DNA" boils down to the arrogance of assuming that the little part that we understand about how it works is the whole picture. My instinct has always been that the "junk DNA" is analogous to computer Code, and the genes analogous to Data. That is, the genes describe the proteins to be manufactured, but the "junk DNA" contains the instructions for when, how much, and under what circumstances to manufacture them.

Erik, Philadelphia, USA

Wow - this one started a lively debate and thank you all for the comments. I used the term 'junk dna' in the same way that biologists do - i.e. to describe stretches of the genome that don't code for proteins. Of course, as several of you spotted, that doesn't automatically mean they are totally useless.

I think this is a particularly exciting field to watch - many biologists feel that those portions must have a function, and I wouldn't be surprised if there's a bit of race to discover it. I'll be keeping an eye on it.

anjana ahuja, london, uk

"Steve isn't saying that the article's author made up the term "junk DNA". He's proposing that it's possible that we may find somewhere down the road that junk DNA might actually do something beyond serving as commas". -- John, Berkeley, CA USA

I do apologize if that wasn't his intent, however, what gave me the idea was his last statement, which i'll quote:

"I live in the hope that this sobriquet has currency only in the heads of those that report science, not those who practise it." -- Steve, Wiltshire

'sobriquet' meaning 'humorous nickname'

Mohammed, London, UK

The term 'Junk' DNA is widely used by scientists (I am one) and textbooks. It does not mean that it is useless but rather that it does not code for anything, ie. proteins. The purpose of DNA is to provide a template for RNA which in turn provides the template for proteins, which is called the 'central dogma of molecular biology'. Some of this junk DNA is probably useless and is a relic from evolution but a number of theories have been suggested as to what useful functions some of the junk DNA has, such as that mentioned in the article. The fun part of science is that we are always searching and we don't have all the answers. That leads us to explore the possibilities.

Neil Pickles, Wirral, England

Mohammed:

Steve isn't saying that the article's author made up the term "junk DNA". He's proposing that it's possible that we may find somewhere down the road that junk DNA might actually do something beyond serving as commas.

John, Berkeley, CA USA

I am not a scientist, nor am I particularly intellectual......
However I am tempted to suggest that some of
the scientists who are trying to decipher the Human
Genome must be a bit dumb to think that because they
don't understand so called "junk dna", then it must be
unimportant..........are we also to believe that Dark Energy,
which makes up most of Universe is also unimportant.....

Badeye, Sydney,

It is thought provoking to consider that scientists are manipulating genetics and assuring us of the safety of so doing while still being unable to actually read the DNA itself, let alone the sub DNA genetics that aren't yet undestood at all.

Mike Poulsen, Reading, Berkshire

Steve,
I don't think Anjana just made up that term for this story. It is documented in every encyclopedia/dictionary.

The noun 'junk DNA' has one meaning:

Meaning #1: stretches of DNA that do not code for genes

Great article and excellent analogy were used. It'll take hundreds of years before we reasonably understand the 'human genome'.

Mohammed, London, UK

On the other hand, 96% commas seems a lot. That would be 2784 commas in the preceding sentence alone!

Jack Thursby, Sheffield,

I'm with Steve, I always thought 'junk' was scientific code for 'we don't know what it does'

Susan, Barry, S Wales

As a consulting engineer who has to deal with things I don't properly understand everyday, it has always struck me as very un-scientific to talk about junk DNA.

DNA was discovered when I was a boy in short trousers (literally) and for something that is as complex as it is, it is obvious that it will take many decades, if not centuries for every last nuance to be understood.

To claim, a mere 50 years after its discovery, that vaste swathes are 'Junk' simply because their function is neither known nor understood, is surely arrogance of the very worst sort.

I live in the hope that this sobriquet has currency only in the heads of those that report science, not those who practise it.

Steve, Wiltshire,