Reading the book of life

The biggest puzzle: Human DNA

The blueprint of humanity, the book of life, the software for existence - whatever you call it, decoding the entire three billion letters of human DNA is a monumental achievement.

It's certainly the biggest thing to hit biology since Darwin - it's probably the most important science project ever

Professor Martin Bobrow, genetics expert

The first draft was announced on 26 June 2000 and many argue it is science's greatest achievement - Nobel prizes are a certainty. The fact that it was an unthinkably difficult task just 15 years ago makes its completion all the more dramatic.

The 2m-long string of DNA found in nearly every human cell contains the instructions for every physical aspect of your body, from the pattern of fine capillaries in your lungs to the unique speckled pattern of your iris.

It is much easier to demonise Celera than justify the hundreds of millions of dollars the Human Genome Project has wasted

Dr Craig Venter, Celera Genomics

Access to such fundamental information promises a new era of medicine and long-term hope for sufferers of a myriad of illnesses.

But the final stages of completing the first draft of the human genome have taken an ugly turn. Brilliant scientists have accused one another of immorality and ignorance.

Market driven

On one side are humble-living, publicly-funded scientists, who aim to bequeath the raw human code to the world, free of charge. They are part of a 12-year, $3bn project, of which $500m will be spent on the human genome.

On the other are privately-funded scientists who say only the rigours of the market and the investment of big business can hope to reap rapidly and efficiently the benefits of decoding human DNA.

Celera want to establish a monopoly sequence on the human sequence - Craig has gone morally wrong

Dr John Sulston, director of the Sanger Centre

One, Craig Venter, caused uproar in 1998 by saying he would decode the entire genome in just three years at a tenth of the cost of the public project. He may well do it - in April he announced all the chemical letters of DNA had been read, they just needed to be assembled into the right order.

Adding to the acrimony is a raging argument over who should own the pieces of the human blueprint being churned out, every minute of every day. The people with your genes in their hands could amass fabulous wealth.

Observers ask if that would be fair reward for boosting healthcare further than ever before or profiteering from property belonging to the human race.

Painful disease

The knowledge that decoding the human genome brings also questions existing medical ethics. If tests show that an unborn child will die of a painful disease in his or her teens, who should decide what should be done?

And some argue that the whole achievement is over-hyped and that crucial areas of human life are more influenced by the environment in which we live, rather than the genes we inherit.

The human genome

Three billion letters

3,000 miles of type

200 telephone directories

One DVD disk

Most agree that the first draft of the human genome is simply the end of the beginning. They say we now have the letters which describe human biology, but we have to decipher the words, or genes, and then understand the language, or gene function.

One thing, however, is sure. Once we have decoded the human sequence of DNA, it cannot be made secret again.

"It'll exist on the world's computers for as long as we exist," says Dr John Sulston. "It's a project of truly biblical proportions."

And, for better or worse, the world will never be the same again, for any of us.

By BBC News Online's Dr Damian Carrington