Letters archive

In your special report on vitamins, you could well have included iodine as a desirable trace mineral (30 August, p 32) . I recently noticed a mildly swollen thyroid gland in the neck of an otherwise healthy 10-year-old. This swelling disappeared after four weeks of iodine supplements. Since then I have watched passers-by more closely, …

• The UK's NHS advises taking no more than 0.5mg a day of iodine supplements and that more could be harmful. Tinctures vary widely in strength: best consult a doctor before self-medicating. Good food sources of iodine include sea fish.

In your article on vitamin and mineral supplements, you conclude that many of the claims for coenzyme Q10 (CoQ10) are unfounded. However, I was surprised that no mention was made of the possible benefit for people taking statins. Like many people on statins I take CoQ10. It will be interesting to see if any future …

• Statins have been associated with a drop in CoQ10 levels, but the evidence for supplements is still weak, and the UK's National Institute for Health and Care Excellence (NICE) recommends against offering CoQ10 to patients receiving statin treatment.

Instead of the losing battle against poachers (23 August, p 6) , would it not be far more effective to screen David Attenborough's Life On Earth documentary wherever products from endangered animals are sold? Increasing understanding of our place in the animal kingdom, ecology and the meaning of extinction would be a huge help in …

Your leader on intelligence trends was most welcome (23 August, p 5) . I would venture one other factor as key to IQ performance, and that is confidence, or the expectation of success. A recent review published by the Institute of Education at the University of London found that the performance of different types of …

Bob Holmes writes that a small downward shift in the mean IQ of a population will cause a relatively large drop in the number of high IQ individuals (23 August, p 30) . But that is dependent on the distribution of different IQ scores – the shape of the curve – remaining constant. Does it? …

• Some predict the curve will stretch to the left. As high IQ couples tend to have fewer children, more children are born to couples with mixed levels of IQ. The result is a reduction of variance at the high IQ end of the distribution, coupled with an increase at the low IQ end ( …

In his article on the search for magnetic monopoles (16 August, p 34) , Richard Webb refers to unfounded fears that turning on the Large Hadron Collider might produce strange anomalies that would devour the planet. Perhaps, however, he ought to be worried about the flood of anomalies that the isolation of a magnetic monopole …

Naomi Lubick quotes an estimate that $384 billion is needed over the next two decades to deliver drinking water across the US (16 August, p 38) . This is a seriously scary number, at least until you work out the cost per citizen per week. This comes to about $1, or around $4 per month. …

Philippa Skett writes that there are five strains of the Ebola virus, four of which are deadly to people (9 August, p 7) . We know that Edward Jenner found that vaccinating humans with some of the cowpox virus granted them immunity from the more dangerous (and closely related) smallpox virus. Would it be correct …

Steven Ashley describes schemes to generate electricity from Earth's infrared emissions (23 August, p 38) . Surely if these emissions take heat from Earth into space, then capturing and converting them into electricity (and ultimately, to heat) will be a very effective greenhouse effect, perhaps even more effective than that of carbon dioxide? Birchington, Kent, …

I noticed the image of an old friend accompanying your story on the decline of Neanderthals (23 August, p 10) : the skull of an early Homo erectus that I helped excavate in 1984. The caption read "40,000 years dead", but that individual died about 1.5 million years ago. Might I suggest that you use …

Hal Hodson seems to suggest that if the US fails to build a connecting oil pipeline to Canada, the tar sands won't be fully developed (16 August, p 10) . This isn't the case. Canada could build a pipeline to the west coast and ship the oil to China. Canada currently sends oil from the …

If those who want to move oil on the Keystone XL pipeline to supply their refineries on the US Gulf coast don't get the supply from Alberta, the demand would have to be met by supplies from somewhere else. Would that somewhere else have no emissions impact? Calgary, Alberta, Canada

Bryn Glover makes an interesting suggestion that shale gas deposits are best left undiscovered (30 August, p 31) , but his letter contains a serious omission. He suggests that power-hungry politicians will fall over themselves to help profit-hungry petroleum companies in their search for methane. The omission is that we power-hungry consumers will happily pay …

Ron Barnes asks what to call a neutron without spin (30 August, p 31) . Surely the physics equivalent of a doosra – where a cricket bowler does not put the expected curve into a delivery – should be a neuteron, since it lacks a vital component of its being? As for spin without attached …

So Jason Wright at Pennsylvania State University is scanning the galaxies for waste heat given off by the machines of tech-savvy aliens (23 August, p 11) . I can imagine our first message should we find them: "Hello. Guess what? We are wrecking our planet too!" St Blazey, Cornwall, UK

I can support Erik Foxcroft's observation that individual birds in flocks of gulls and crows may engage in mid-air fights while the flocks as a whole continue flying in their original directions (23 August, p 29) . On this occasion the fighting pairs eventually disengaged and rejoined their flock-mates at the back of the squadrons. …

Jim Petts's description of long haul space flight simulations involving "cramped and unpleasant surroundings in complicated and tubular habitats, limited washing and toilet facilities, poor communication and food delivered through a service lock" would suggest that my daily commute into London should have made me an ideal candidate for interplanetary exploration by now (23 August, …

• It's not only the European Space Agency that had trouble placing its satellites (30 August, p 7) . We need a geography lesson: the satellites were launched from French Guiana , not French Guinea ( 1891-1958 ). • The cracks were showing in our story on spiral microfractures (30 August, p 12) : the …