Letter
In drawing a distinction between risk as it relates to skiing and GM food production, Tudge asks: “Where is the exhilaration in GM soya?”.
Could I suggest that making inroads into world hunger and protecting the environment and society from toxic pesticides might provide the answer to this question?
Sex with Neanderthals
DNA evidence that humans contain no genetic material derived from Neanderthals seems to be being taken as evidence that the two species never came into contact (17 May, p 14). Such conclusions, though, betray an unspoken assumption that the two species were capable of interbreeding successfully.
As far as I am aware there is no evidence to suggest that this was definitely the case. If this is so, the lack of a Neanderthal genetic legacy in modern humans could equally indicate that human/Neanderthal matings either could not produce viable offspring, or, at best, produced sterile hybrids. Both these possibilities would allow full contact between the species, up to and including sex, without it ever showing up in the DNA.
Beautiful instrument
Your article about the Pierre Auger Observatory contains an inaccuracy of which your readers should be aware (17 May, p 9). At present, just over 2 per cent of the Southern Observatory has been constructed and is operating as a prototype instrument, not 10 per cent as you suggest. We expect to have 10 per cent of the complete instrument up and running by the end of 2003. All subsystems are performing within or beyond specification, a great tribute to the engineers and physicists building it.
With this prototype system, there was never any expectation of science results. As with other large projects, we believe strongly that scientific results must be vetted thoroughly before they are publicly released. To do otherwise would foster chaos.
What we chose to make available to the public were technical notes and progress reports. This practice will continue, but after some monitoring of the contents.
We will find what nature has to tell us when we have completed our beautiful instrument. We aim to measure the properties of the highest energy cosmic rays with unprecedented precision, with the objectives of discovering what these particles are, where and how they are accelerated, and of studying interactions at the highest energies.
Should the cut-off be seen, we will have discovered an important clue to the origin of the highest energy cosmic rays. Should the cut-off not be observed, we may have identified an indicator of important new physics. Whatever the outcome of our work, we are certainly not on a wild goose chase.
Einstein and Mach
Paul Wesson may be correct in saying that Mach’s principle is not incorporated in the equations of general relativity (17 May, p 30). However, a strong connection between the distant universe and rotating bodies is implied.
In Chapter 23 of his popular exposition Relativity, Einstein shows nicely how space-time is far from Euclidean when a rotating platform is considered as stationary with the rest of the universe rotating around it. The observer at the centre is subject to an enormous force as a result of this rotating mass.
Of course, at the centre this force balances out in all directions (assuming the universe is isotropic) but what about at points away from the centre? Perhaps it doesn’t quite balance and we are left with the so-called “centrifugal” force?
Sticking to the ceiling
I was fascinated by the article explaining how a gecko can stick to a surface, supporting its own weight with only one toe (17 May, p 15). What I would like to know is how the gecko is able to stick or release each foot at will as it moves across a surface. Why is it not stuck fast and unable to move once it makes contact?
My mind boggles at the thought of human geckos. How would they interact with modern buildings with thin plasterboard surfaces secured by short nails?
The whole thing reminds me of a story which I read many years ago in The Compleat Practical Joker. It told of a wealthy man who amused himself by inviting indigents to his home, wining and dining them until they were senseless, and then placing them in an upside-down room with a concealed entrance. The furniture was stuck to the ceiling and a chandelier emerged from the floor. He laughed uproariously at the antics of his guests as they came round and tried to regain the floor. There is a just ending to the story as he died of apoplexy laughing at one of his victims.
May I add that if the person to whom I lent the volume around 1950 is reading this letter, may I please have my book back?
Letter
It is by no means obvious that the world is facing an epidemic of chronic illnesses induced by diet. The supposed links between diet and conditions such as cancer and respiratory disease are not strong. There is still great uncertainty about the causes of such diseases.
Brundtland claims that changes in diet would generate positive health outcomes. But again, the evidence to support this is not strong. A reduced- fat diet rarely extends life expectancy or even reduces heart disease. And even if they would do, such changes are incredibly hard to bring about. People like their meat and soft drinks too much to forgo them easily. It is likely that this campaign will simply fail.
The world faces serious health problems. If Brundtland wastes millions on a pointless campaign that won’t even extend the lifespans of the fat middle-aged westerners it is aimed at, then there is even less money to be spent on preventing HIV in developing countries. How can Brundtland justify throwing more money away telling the wealthy what they already know when the extra funding would be better spent on preventing malaria?
Pekka Puska, Director, Noncommunicable Disease Prevention & Health Promotion, World Health Organization, writes:
鈥� The evidence shows beyond reasonable doubt that a few behaviours and related biological risk factors, including high blood pressure, high blood cholesterol, tobacco use, excess weight and obesity, are strongly and causally related to the major chronic diseases. There is also strong evidence that these risk factors and behaviours can be influenced.
J. R. Johnstone refers to the randomised controlled trial as the “gold standard” of testing. It should be noted that public health experts see comprehensive, population-based, preventive interventions (involving policy decisions, broad health promotion measures and involvement of the health services) as the effective response to the challenge of changing health-related lifestyles. Such interventions cannot be evaluated by classical trial design.
There is plenty of evidence that lifestyle interventions work. The best documented national ones are changes in diets (and some other behavioural risk factors) in Finland, resulting in a dramatic reduction in deaths from coronary heart disease. There is also strong evidence that reduced salt intake in Japan resulted in a dramatic reduction in hypertension and deaths from strokes.
We at the WHO are convinced that evidence-based and carefully implemented interventions at the population level can have a meaningful impact on chronic disease-related behaviours, and that, for example, reducing smoking rates or cutting blood pressure or blood cholesterol levels as a result of dietary changes can have a significant positive impact on chronic disease rates, life expectancy and quality of life.
Where's the DU bias?
It was unfair of Brian Spratt to dismiss the report of the European Committee on Radiation Risk (ECRR) as merely some anti-nuclear platform (17 May, p 24). The Royal Society’s own evidence on depleted uranium is arguably irrelevant since DU particles are entirely novel and cannot be equated with uranium ore dust. There are only a few relevant studies and these are alarming.
But the ECRR report has a much wider remit than DU. It is a response to the scientifically indefensible risk model maintained by the pro-nuclear International Commission on Radiological Protection (ICRP). The dissonance between the predictions of the ICRP and observation (on DU, on nuclear site leukaemias, on Chernobyl effects) is now so great that the UK government has set up a new committee () to investigate.
The ICRP’s model was developed in the cold war to provide a justification for nuclear weapon development. Many scientists involved in it turned against it (for example, Karl Z. Morgan, John Gofman, Ed Radford). Political pressures maintained it through decades of new discoveries, such as the structure of DNA, cell repair, SOS response, genomic instability, bystander effect, cell communication fields and minisatellite mutations. It is an insecure basis for Brian Spratt’s offhand dismissal of the ECRR report.
The ECRR includes many eminent radiation researchers, members of the Russian Academy of Sciences, professors of radiation physics, eminent epidemiologists, science philosophers, lawyers 鈥� a long list of serious and powerful thinkers, authors of hundreds of contributions in peer-reviewed literature 鈥� who have come together to try and develop an accurate and inductive model based on a rational analysis of mechanistic and epidemiological evidence. Such a project is long overdue. It marks the resurgence of European science and the end of the blind adherence to (largely US) political control.
Hope and hype
Colin Tudge asserts that scientific discoveries such as penicillin would have been given the green light under the precautionary principle (17 May, p 23). However, this is accepted with hindsight. Yes, drugs such as penicillin would, were the benefits known in advance, be blindly accepted. However, in an era where mass media can spread myths quickly, scientific rationale is often rapidly lost.
Can we really be certain that the benefit of any scientific discovery would win through the tide of speculation and hype? Anyone with an agenda can spread misinformation, quickly prejudicing arguments. We all recall the images of strawberries with fish eyes when GM crops first came to light.
Lifestyle and health
The director-general of the World Health Organization, Gro Harlem Brundtland, claims “the world is facing an epidemic of chronic illnesses” and that “most of the damage could be prevented through simple changes in diet, by being more active and by not smoking” (3 May, p 23). But 30 years of trials contradict her.
For many years the preferred method for testing such a claim has been the randomised controlled trial, often referred to as the “gold standard”. In such a trial a test group of subjects are encouraged and counselled to improve their diet, to exercise and reduce their smoking. An otherwise similar control group are left to their own devices. After some years the health and death rates in the two groups are compared to determine the effects of any improvement in lifestyle.
There have been a number of such studies, with various combinations of these three lifestyle factors, including the WHO collaborative trial (60,881 subjects, 6 years), the Goteborg trial (30,022 subjects, 11.8 years) and the Multiple Risk Factor Intervention trial (12,866 subjects, 7 years).
These and another eight trials were conducted over three decades, one of the most expensive and sustained series of biological experiments in the history of medical science. It was generally believed that these trials would show once and for all that a healthy lifestyle would increase life expectancy. They showed nothing of the sort. None showed any improvement in life expectancy and two showed a significant reduction in life expectancy in the test group.
Can Brundtland give even one example of a trial which shows that an improvement in lifestyle improves life expectancy?