The evil Doctor Venter strikes again. Not content with having stolen our biological past (it was he who patented the human genome) he is now trying to steal our biological future too.

This week it was reported that Dr Venter had created, artificially, the first living copy of a bacterium. In keeping with his sinister reputation, he did not choose a friendly bacterium to copy; instead he copied Mycoplasma genitalium. M. genitalium lives, as its name suggests, in our genital tracts and it is easily transmitted during sex. Currently, it is assumed to be relatively harmless, but who knows what Dr Venter intends to do next with it, was the subtext of some news reports?

On closer examination of Dr Venter's paper, the work is not as dramatic as some reports suggested. He selected M. genitalium not for malign reasons but simply because its DNA is shorter than that of most bacteria. Nonetheless, it still comprises 582,970 chemical units or “base pairs”, strung along as a filament.

And Dr Venter has not yet actually copied the bacterium itself. Instead, he has only synthesised its DNA in the test tube. A number of virus DNAs have already been synthesised artificially, so although the synthesis of the DNA of M. genitalium represents a technical tour de force (it is over 10 times longer than the longest virus DNA synthesised to date) it represents no fundamental breakthrough, biologically. It is not the first living DNA to have been synthesised artificially.

But Dr Venter will shortly turn his DNA into a living breeding bacterium, and because viruses are parasites whereas bacteria can be self-sufficient, he is on the point of creating a life form that can live and breed autonomously.

Dr Venter is a great self-publicist (he announced his achievement at the World Economic Forum in Davos) but he is simply the latest in a long line of biochemists who have punctured life's claims to specialness. Until 1828 it was believed that life, with its so-called “vital forces”, owed nothing to science, but in that year Friedrich Wöhler synthesised urea in the test tube. Since then, chemistry's invasion of biology has been unstoppable.

So it is not science fiction, it is inevitable, that within our children's lifetimes, molecular biologists will tweak the human genome. If we can re-create existing bacterial genomes, we will be able to create new improved human ones. The ills that flesh is heir to are many, but thanks to DNA chemistry they will be abolished. Diseases such as cystic fibrosis or muscular dystrophy will be eliminated as thoroughly as smallpox. And the greatest ill of all - ageing - will also be conquered.

It was Sir Francis Bacon, the Father of the Scientific Method, who wrote in his Valerius Terminus of 1603 that the purpose of science was the “discovery of all operations and possibilities of operations from immortality (if it were possible) to the meanest mechanical practice” - and immortality is possible. We know that some animal species such as the hydra and the sea anemone are apparently immortal, and we are beginning to understand the chemical operations by which they achieve that. Indeed, those mechanisms may already operate within our own testes and ovaries.

So one day a successor of Dr Venter will discover how to render all our cells as immortal as the hydra's or the sea anemone's. That day will see the beginning of the end of cancer, coronary heart disease and the other horrors that are largely caused by ageing, and though it could introduce new horrors such as terminal boredom and the end of inheritance taxes, it will be memorable.

Ageing is a planned process. The main cause is oxygen which, as it is consumed during ordinary metabolism, produces dangerous side-products called free radicals. These side-products cause cancer, atherosclerosis, and - by destroying brain cells - dementia. But free radicals can be countered by enzymes that mop them up. Unfortunately, such damage limitation is expensive in terms of energy.

In his book Time of our Lives Professor Tom Kirkwood explained that evolution trades ageing against speed. Nature realises that the average mouse, say, will live for only two or three years in the wild because it is so vulnerable to predators. But the average elephant will live for half a century before succumbing to a fatal mishap.

So Nature does not provide mice with enzymes to protect them from ageing, because mice will not last long anyway. Nature, instead, provides mice with fast metabolisms, to help them flee danger. Consequently, mice naturally age fast. But elephants move ponderously, because Nature has given them little energy for running around. Instead, Nature pours energy into their anti-free radical enzymes, protecting them from ageing.

Most of us feel that our lives are too short but one day, thanks to the work of Dr Venter and others, we will introduce better anti-ageing enzymes into our DNA. The consequence will be a slower, more chilled species, but we will live longer.

Craig Venter's autobiography reveals a driven man. He expends a lot of energy, so he may not live long. But thanks to him our children will. Not so evil after all.

Terence Kealey is a clinical biochemist and author of Sex, Science and Profits

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