Like a duck to water
In his interesting article on flying submarines, Paul Marks discussed the design history of such machines (3 July, p 32). One early design he didn’t mention, however, was the , an Italian racing seaplane built for the Schnieder Trophy race in 1929.
While not fully submersible, the Piaggio P.7 was designed to float on its wings with the lower fuselage submerged. The propulsion system was unusual. While in the water, the engine powered a marine propeller in the tail. When the pilot wished to take off, the seaplane would rise on waterskis until the front propeller was clear of the water. Then the engine’s power was sent to the front propeller, theoretically allowing a normal seaplane take-off. The craft was built, but never became airborne.
From Stephen Winkworth
I wonder how many people reading your article “A sub takes to the skies” were reminded, as I was, of that boys’ adventure classic The Flying Submarine by Percy F. Westerman. Written nearly a century ago, many of the problems you outline are mentioned, although the solutions 鈥� based on a techno-magical, gravity-neutralising gas called “helia” 鈥� are appropriate to airships rather than aircraft.
Westerman admitted one limitation to his flying submarine, “The Amphibian” 鈥� it could not imitate diving birds because, in order to submerge, the vessel had to undergo the lengthy process of taking on water to expel the helia.
Little has changed. The more modern technology of the jet engine also has problems with the transition from air to water, as Graham Hawkes, your quoted engineer, warns. Perhaps developers will have to look to string theory for ways to create a gravity neutraliser.
Opio, France
Disease and genes
In discussing why genetics researchers are not finding genes for disease susceptibility, the “dark matter” of genetics, Peter Aldhous and Michael Le Page omitted the simplest explanation of all (19 June, p 30). Maybe they can’t find them because they are not there.
There are some excellent reasons for thinking that genes for modern diseases are rare or absent altogether. For most of the diseases under discussion there is excellent data for environmental causes. Furthermore, the evidence for their genetic causation relies on estimates of heritability based on twin studies.
Not every geneticist thinks twin studies are good science. I heard Martin Bobrow of the University of Cambridge describe estimates of heritability based on them as “poisonous” at his talk entitled The Genetics Revolution at the Wellcome Trust Genome Campus in Hinxton, UK.
Richard Lewontin has criticised heritability measurements in his book, Biology as Ideology: The Doctrine of DNA, for the reason that since gene effects depend on environment, and environmental effects depend on genes, there can be no fixed relationship between genes and environment.
Emmanouil Dermitzakis and Andrew Clark also recently concluded that DNA will not be useful for predicting disease because there is not enough genetic variation in the general population ().
From Georg Pedersen
To be able to make medical decisions based on knowing one’s genome might be valuable, but the idea of being able to predict with any accuracy the diseases one would get as one ages is naive and shows ignorance of conclusive research in the field.
The largest epidemiological study ever done 鈥� by T. Colin Campbell at Cornell University in Ithaca, New York, and colleagues in Oxford and China, and reported in the book 鈥� found that genetic pre-disposition is quite insignificant compared with what you eat, and what you don’t eat.
In the same book, Campbell shows that work on rats tells the same story. When two groups of rats were given a very potent carcinogenic substance, aflatoxin, and fed on diets with either 5 per cent or 20 per cent protein, the group with the higher protein intake all died of liver cancer, while not a single animal in the other group had any trace of liver cancer, in spite of consuming the aflatoxin. In other words, you can turn on and off cancer by simply varying the amount of protein consumed. Genetic variations and the presence of such a strong carcinogen is insignificant. The book confirms a similar result with a whole range of common diseases in humans.
Sydney, Australia
Naturally reared
I am amused by the idea of creating genetically modified pigs with meat rich in omega-3 fatty acids (10 July, p 34). A lack of omega-3 is not inherent in meat; intensive farming causes a loss of omega-3 from the meat, combined with an infiltration of other fats.
My team has found that the amount of the omega-3 fatty acid docosahexaenoic acid in chicken meat has dropped from 170 milligrams in 1970 to between 25 and 60 milligrams today (Public Health Nutrition, vol 13, p 400). This is a direct consequence of intensive feeding, largely with cereals, and a lack of exercise, which leads to the loss of fast-acting muscle fibres 鈥� which are rich in omega-3 fatty acids. This is why chicken legs, which were once dark grey, are now nearly as white as the breast.
Animals allowed to roam and choose their own food are naturally rich in omega-3 because their diet is rich in vegetation, which is their primary source of omega-3 fatty acids. To get meat, eggs and milk rich in omega-3, we simply have to rear animals properly, which means in a biologically appropriate manner.
Unhappy families
Why should Neanderthals be considered members of our own species, Homo sapiens, just because interbreeding has been shown to produce fertile offspring, as your editorial suggests (15 May, p 3)?
If this is a criterion for species membership, then we shall have to accept that jaguars and leopards are the same species. The same would go for jaguars and pumas, polar bears and brown bears, wolves and coyotes, and domestic sheep and goats. In several of these cases the animals are classified not merely as distinct species but as distinct genera.
If we are not willing to merge these species, then why should we merge modern humans and Neanderthals? The clear anatomical differences between them and us argue against such a conflation.
Climategate candour
Readers may depend on your editorial to form their opinion of “climategate” (17 July, p 3). Regrettably, while it contains some fair points, there is enough distortion and imprecision remaining to perpetuate the sense that there is still a case to answer on the science. This is despite clear findings supporting the honesty and integrity of our scientists in all three independent investigations into the affair.
To address some specific issues. You quote Ron Oxburgh’s statement that his investigation was not concerned with the science. However, in his report he notes that his panel was concerned with ““. This seems entirely consistent with the way research works 鈥� with conclusions becoming less provisional over time, until they approach the elevated status of “fact” or are replaced by different conclusions. In the observational sciences, that process develops through the honestly and scientifically justified interpretation of data. Similarly, several questions in Muir Russell’s review directly addressed the science, including a specific examination of reproducability. The panel found of colleagues in the Climatic Research Unit (CRU) that ““.
In addition, CRU’s research has been peer-reviewed for top-rate journals and reaches similar conclusions to that of many other groups around the world using a variety of variables and indicators. Although peer review is not perfect, it is a rigorous test of the science conducted and its findings.
We fully accept that we should in most circumstances have been more helpful in responding to queries. However, we reject the suggestion that we have failed to meet our legal obligations to share data “even with… critics”. On these and other matters of fact we found the editorial wanting, and a further discussion can be found on the .
Blue-green funerals
Helen Knight reports on options for eco-friendly funerals, but those mentioned are high-tech and energy intensive (12 June, p 8). A simpler solution is burial at sea. An ethically acceptable method would have to be found to allow for large numbers, but the principle was used successfully in the UK’s Royal Navy for centuries.
One distinct advantage would be the laying down of a source of oil for whatever species roams the Earth in a few million years time.
Biomass block
In writing about the use of second-generation biomass, such as plant waste and paper, to produce biofuels, Helen Knight did not mention that fermenting the sugars resulting from cellulose hydrolysis produces a less than 15 per cent solution of alcohol in water (29 May, p 22). A great deal of energy is used in concentrating the alcohol to produce a useful fuel additive.
Biomass is difficult to use directly in conventional power stations because of its corrosive and low-melting-point ash. I suggest that the best way to use biomass is to use the hot gases produced by burning it to dry the coal feed to power stations, which could improve their thermal efficiency.
For the record
鈥uons are not larger than electrons, but they are more massive (10 July, p 10).
鈥� Preying has nothing to do with it: the poster boy of risky sex is the male praying mantis (3 July, p 36).
鈥� In our diagram of an optical illusion, the inner circles were not identical as claimed. In two of the four images, the pattern was horizontally displaced (10 July, p 28).