Letters archive

As Dominic Dyer made clear in "Kill all known germs" (25 June, p 28) , there is no evidence that certified organic products are more likely to be contaminated by Escherichia coli . All food is susceptible, and recent European Union research even shows less contamination in organic livestock. The answer lies in controlling risks …

Some crucial steps in the journey of single-celled yeasts to multicellular form occur very quickly, far quicker than the 350 generations over 60 days noted (25 June, p 10) . Even the 90 minutes it takes for a new cell to bud off is a long time compared with the 5 minutes or so needed …

Anyone working with children needs to heed Jon Ronson's article on misdiagnosis of childhood bipolar disorder (4 June, p 44) . Parents have lost their intuition about normal behaviour: children are meant to be childish. The reason those aged under 7 cannot hold two emotions or two thoughts at a time is that they have …

The idea of using Google Search for sending hidden messages (18 June, p 26) was less than convincing for several reasons. You would need to be in possession of a codebook, which would be a double liability. Being caught with a codebook is bad enough, but if it falls into the wrong hands, the whole …

I thought it was eccentric to have a favourite number until I read your interview with Alex Bellos (25 June, p 29) . Mine is 23, because it is the temperature in degrees Celsius at which I am most comfortable, my favourite Mozart piano concerto and the first prime number made up of consecutive digits. …

The diving-bell spider's use of a web bubble as a gill came as no surprise (18 June, p 20) . I refer you to Gerald Durrell's 1969 book Birds, Beasts and Relatives . I quote: "This was now the spider's home in which it could live quite comfortably without having to pay frequent visits to …

The reference to crows sharing information on humans regarded as a threat (2 July, p 5) reminded me of noted zoologist Konrad Lorenz's 1966 book On Aggression . Since reading it in 1971, I have never forgotten his description of crows using a specific call to alert other crows to the approach of a person …

Using a cryptographic approach to crack foreign languages is a nice, fresh approach to machine translation (18 June, p 23) . It might also offer intriguing possibilities for decoding another form of communication. Researchers working with bottlenose and spotted dolphins have identified some elements of their "language", such as their signature whistles. In addition, their …

Looking at the diagrams with a hidden message in the article on understanding risk (25 June, p 31) reminded me of how sonar operators used sonar printouts to detect the presence of submarines. At first sight, the printouts looked as if someone had shaken pepper and salt over the grey paper and produced a meaningless …

I hesitated to write, but in the interests of science here goes. In "Lopsided love" (18 June, p 42) Menno Schilthuizen mentioned the anatomical oddity of the left testicle hanging lower in about 2 out of 3 men. I had noticed this asymmetry about myself, and wondered why it occurred. I realised that when sitting, …

With reference to the cover line "Sky's the limit: gliders that never have to land" (25 June) , in aviation the sky is not the limit. The ground, however, definitely is.

•The diagram in "Creature contacts" (28 May, p 32) gave the impression that dogs originated in East Africa 32,000 years ago. While it is generally thought they originated there, the 32,000-year-old fossil mentioned in the text was found in Belgium .