One in 10 experiments involving the use of laboratory monkeys serves no benefit whatsoever, whether to scientific understanding, medicine or animal welfare. This was probably the most striking conclusion to emerge from the Review of Research Using Non-Human Primates by a panel of experts led by the eminent Cambridge zoologist Professor Sir Patrick Bateson.

There was another finding in the report that should cause equal anxiety. The experts concluded that it was very difficult to detail the precise medical benefits accruing from the majority of studies involving monkeys that they had retrospectively investigated over a 10-year period between 1996 and 2006.

A possible reason for this, other than, of course, the uselessness of using monkeys, is the long time-lag between basic scientific discoveries and the practical applications that emerge from them. It may well be that 10 years is just not long enough to be able to witness the new treatments or cures that emerge from the particular primate experiments the panel investigated.

This is a familiar problem in science, especially medical science, which has the expectation of providing real benefits to patients, rather than merely a better understanding of the natural world. It can take many years, and sometimes decades before we reap the rewards of a scientific breakthrough, and it is often only with the benefit of hindsight that true breakthroughs can be distinguished from damp squibs.

Take for example the publication of the human genome 10 years ago. There were great expectations in 2001 that this complete map of the human genetic code would revolutionise medical treatment in the decades to come.

The hype did not just come from journalists like myself. President Bill Clinton called it the "most important, most wondrous map ever produced by mankind", while the then prime minister, Tony Blair, called it a "breakthrough that takes humankind across a frontier to a new era".

And it was not just the media and the politicians who got caught up in the excitement. I remember well the words of scientist Mike Dexter, the then head of the Wellcome Trust, which funded much of the Human Genome Project, who said at a press briefing that the completion of the genome would eclipse the significance of the Moon landings and even the invention of the wheel.

A decade or so ago it was not unusual to see predictions about the revolution in "personalised medicine" that would emerge from knowing the full three-billion-letter sequence of the human genome. We would go to our doctors with a computer read-out of our DNA and would be prescribed medicines specifically to suit our type of genes – a sort of bespoke medicine more in tune with Savile Row than Harley Street.

The reality is that although there are one or two such "genomic" drugs now available, they are incredibly expensive. The idea of a widespread, personalised approach to medicine looks laughable in the face of a cash-strapped NHService which has to ration operations for cataracts and varicose veins.

In his excellent review of the science coverage by the BBC, the geneticist Professor Steve Jones makes the point that journalists often tend to over-egg a scientific achievement in order to make it sound more important than perhaps it is. It can be done by simple phrases like "a penicillin moment" in otherwise factually sound and insightful broadcasts.

We are all guilty of this – journalists, politicians and, yes, scientists themselves. It is human nature. We want to transmit the excitement of discovery to a wider electorate, to convince a funding organisation that a piece of basic research will produce real benefits to society, and yes to tell a story in the most dramatic way we can without, hopefully, distorting the truth.

Unfortunately, in reality we cannot predict the true importance of a "breakthrough" with any certainty. Scientists try their best to fathom the unfathomable, but they are often no better than the rest of us when it comes to knowing whether anything truly worthwhile will come out of a piece of new science, however breathtaking.

Rarefied world of the double helix

Every day I pass the building site next to London's St Pancras Station that will be the Francis Crick Institute, formerly known as the UK Centre for Medical Research and Innovation. As the now-defunct title states, it is to become the pre-eminent place in Britain where advances in medical research are translated into practical benefits for society at large – the "innovation" bit.

Crick, along with Jim Watson and Maurice Wilkins, unravelled the three-dimensional structure of the DNA double helix. It was a bit of basic, fundamental science that would eventually result in untold practical benefits and a multibillion-pound biotechnology industry.

The publication of the structure in Nature in 1953 was barely noticed outside the rarefied world of these early molecular biologists. There were no satellite link-ups between US presidents and British prime ministers, no wall-to-wall coverage in the national press or in-depth television interviews. It was a different era, when scientists spoke to themselves, rather than the great unwashed public.

The building site is surrounded by a 20-foot wooden fence topped by razor wire presumably as a precaution against animal activists. A pity that the wood comes from Brazil (I saw the Brazilian stamps before they were painted over). I don't know what the institute's new director, Sir Paul Nurse, will make of that given his devotion to green causes.

s.connor@independent.co.uk